ammonia. In the synthetic method, ammonia gas is added to dilute sulfuric
acid, for a chemical reaction. The resultant product is a solution of
ammonium sulfate. As the solution becomes more and more concentrated during
the reaction process, finally crystals of ammonium sulfate are precipitated.
After separation and drying, ammonium sulfate particles are formed. In the
recovery method of by-product ammonia, during the coking process ammonia in
the coke oven gas is absorbed by dilute sulfuric acid, to make ammonium
sulfate. About 25 to 30 chin of ammonium sulfate can be recovered when
refining one ton of coke. Ammonium sulfate made by the synthetic method is
comparatively pure and white in color. Ammonium sulfate as the by-product
of coking is frequently mixed with impurities with different colors. How-
ever, this has no undesirable fertilizing effect.

There are many ways of applying ammonium sulfate; it can be used as basic
fertilizer, seed fertilizer or follow-up fertilizer. However, the fertilizing
effect is best when using ammonium sulfate as follow-up fertilizer. When used j
as seed fertilizer, small amount of ammonium sulfate should be applied and :
it should be mixed wet with the seeds. Otherwise, some of seeds may fail to
sprout. When used as basic fertilizer, the amounts should also be small.

The best effect comes from mixing with farmyard manure as the basic fertilizer.
When used as follow-up fertilizer, generally 10-50 chin of ammonium sulfate

can be applied per mou. When nitrogen fertilizer is applied in paddy fields

as follow-up fertilizer, overirrigation should be avoided. No water drainage
should be conducted 7-10 days after application to avoid loss of fertilizing
nutrients.

When ammonium sulfate is used as follow-up fertilizer, either dry or wet
application is good. Application to cotton plants is best in the seedling
period and the time between the incubation period of unopened flower buds to
the vigorous period of growing cotton bolls. To sorghum or corn plant,
fertilizer is better applied in the seedling period to sometime before
tassel growing. Ammonium sulfate can be applied as follow-up fertilizer,
one to three times, to paddy rice or wheat plants in the sprouting period or
the time between node growing to the tassel incubation period. Follow-up
fertilizer can be applied one to two times to hemps after seedling trans-
planting to the period when unopened flower buds appear. One to three times
of follow-up fertilizer can be applied to vegetables after seedling trans-
planting.

Here are precautions when applying ammonium sulfate:

(1) As the ammonium sulfate is an acidic fertilizer, it is. most appropriate
in alkaline or neutral soils. The fertilizer can also be applied in acid
soil but the application time should not persist too long. Otherwise,
excessive buildup of sulfuric acid in soil will cause crusting, disadvantage
geous to crop growth. To avoid this phenomenon, enough lime should be
applied to the soil. Generally, one-half chin of lime should be applied
per chin of ammonium sulfate to neutralize its acidity. However, care
should be taken that ammonium sulfate is not mixed with lime to be applied
to the soil; alternate applications should be made at different times.

-15-



characteristics are similar to those of calcium superphosphate. The water
solution of concentrated superphosphate is acidic reaction, so this is also
a type of acid chemical fertilizer.

Application of concentrated superphosphate is also like that of calcium
superphosphate. The fertilizer can be appropriately applied to a variety
of soils and crops, used as basic, follow-up or seed fertilizer in ditch,
hill or furrow application. Because the concentration of this fertilizer

is high, the application amount should be reduced by two-thirds of the
calcium superphosphate. In fertility, 30 chin calcium superphosphate equals
10-12 chin concentrated superphosphate.

The yield-gain effect of concentrated superphosphate is the same as that of
calcium superphosphate at the equivalent amounts.

3. Ca-Mg-phosphate: this is a gray or dark green powder, odorless and taste-
less. Ca-Mg-phosphate is a citric-acid-soluble phosphorus fertilizer and
usually is insoluble in water, not hygroscopic and not caking. Ca-Mg-phospmte
is alkaline in reaction.

In making Ca-Mg-phosphate, first phosphate rock, serpentine, dunite or dolo-
mite with silica addition are melted at high temperatures. The end product
can be obtained after cooling, breaking and pulverizing. There are three
types of melting processes: blast furnace, electric furnace and open hearth.
The production scale and the content requirements of the phosphate rock are
flexible since no other chemicals are needed as raw materials. In many
parts of China, remodeled small blast furnaces (used for iron smelting
before) are used to produce Ca-Mg-phosvhate to supply local demand. Packag-
ing and transportation are also convenient. This is one phosphorus ferti-
lizer type with rapid acceptance and good fertilizing power in China in
recent years.

There are different phosphorus nutrient contents of Ca-Mg-phosphate due to
the different raw materials and material compounding ratios. The phosphorus
content is 14-18 percent and magnesium content is 12-13 percent.

Generally, Ca-Mg-phosphate is used as basic fertilizer although it can be
also used as follow-up or seed fertilizer. The fertilizer can be applied to
paddy rice, wheat, barley or legumes; however, the best fertilizing effect
is in legumes and green-manure crops. Ca-Mg-phosphate is suitable to acid
and slightly acid soils as well as to magnesium-deficient infertile sandy
soils. The fertilizing effect in acid soils resembles or even exceeds
calcium superphosphate. Ditch, hill or furrow application of the fertilizer
is feasible. The amount applied is 30-50 chin per mou. If the fertilizer
is mixed first with farmyard manure, the fertilizing effect is even better.

Ca-Mg-phosphate is widely applied in various areas of China, especially in
southern provinces, such as Chekiang, Kiangsi, Yunnan, Kweichow, Hupeh,
Hunan and Szechwan. The fertilizing effect is quite good according to
application experiences in these areas. As indicated by studies on the

- 36-



sinicus, L., Tacoma grandiflora, Loisel and Hibiscus esculentus. Next in
effectiveness are buckwheat and rape and less so in effectiveness -- paddy
rice and wheat. The effect of applying phosphorus fertilizer is generally
higher for winter or spring crops. Since there are different phosphorus
fertilizer requirements by crops and the phosphorus content in seeds and
straw of legumes and edible-oil crops are higher than for cereals, the
fertilizing effects of phosphorus fertilizer differ for different crops.

3. Relationship between application method and fertilizing effect of phos-
phorus fertilizer: generally, the effective part of phosphorus fertilizer
that can be utilized by crops is generally only 20-40 percent of amount
applied that year. When part of a phosphorus fertilizer is precipitated

by the soil, generally the fertilizing effect shows up one or more years
later. In addition, by scattering, very little of the fertilizer can be
utilized by the crop. The fertilizing effect is much higher if the furrow,
ditch or hill application is used, because application in concentrated spots
is more effective than scattering.

4, Relationship between individual and coordinated application of phosphorus
and nitrogen fertilizers: coordinated application of phosphorus fertilizer
and nitrogen fertilizer allows these two fertilizers to exploit more of
their potent ‘al for higher yields than in individual application. From
wheat field experiments in the Wu-kung area of Shensi Province, 8 chin
nitrogen fertilizer per mou can increase the wheat yield by 190.5 chin and
8 chin phosphorus fertilizer per mou -- by 23.3 chin. If these two ferti-
lizers are coordinated, by applying 8 chin each of nitrogen and phosphorus
fertilizer, the wheat yield goés up by 229.5 chin, 15.7 chin more than the
total of individual applications of the two fertilizers.

Phosphorus fertilizer on legumes can increase nitrogen nutrient. This is
experience coming from phosphorus fertilizer use by Chinese peasants.
Because root nodule bacteria can fix atmosphere nitrogen in the case of
leguminous green-manure crops. This adds to nitrogen compounds in the
soil for nutrients favoring the current harvest as well as the crop from
the next planting. More phosphorus fertilizer can grow better green-manure
crops. So phosphorus fertilizer used in the growing period of leguminous
green-manure crops increases the soil nitrogen fertilizer for the current
and next crops. This is the increase in nitrogen content coming from the

“application of phosphorus. From calculations on the nitrogen gain in

leguminous green-manure crops treated with phosphorus fertilizer, each

chin phosphorus can mean 1 more chin of nitrogen. As indicated in the
fertilizing effect experiments on Tacoma grandiflora, Loisel, by the
Szechwan Agricultural Research Institute, Kuan-hsien County, the yield

was 1638 chin per mou without phosphorus applied but 2205 chin per mou,
when 50 chin Ca-Mg-phosphate was used -- an increase of 567 chin Tacoma
grandiflora, Loisel. The wheat yield was 338 chin per mou without phos-
phorus fertilizer in the preceding cultivation of green-manure crop. How-
ever, the wheat yield was 384 chin per mou with phosphorus fertilizer applied
in the preceding green-manure crop cultivation -- a gain of 46 chin per
mou. However, if this 50 chin Ca-Mg-phosphate is applied right in the wheat

- 32-



and wheat, the consumption of potassium nutrient halts almost completely
in the flowering period. However, in some other crops, potassium consump-
tion is comparatively uniform throughout the growing period. So potassium
fertilizer should be applied at the right times to suit different crops and
different growth periods. Generally, the fertilizing effect is significant
when potassium fertilizer is applied early.

The raw materials used in making potassium fertilizers are sylvite, alum
stone, carnallite, brine and niter. Sylvite is a mixture of potassium
chloride and sodium chloride; carnallite is a double salt of potassium
chloride and magnesium chloride. The pulverized rock of these minerals
can be used as a crude potassium fertilizer. Like pulverized phosphate
rock, this is the simplest processable fertilizer. However, high amounts
of impurities are in these minerals and some impurities harm the soil or
erop growth. If processing and refinement of these minerals are done,
the fertilizing power can be raised and impurities reduced.

Here are main types of potassium fertilizers.

1. Potassium chloride: this is one main kind of potassium fertilizer; it is
a white, brown or yellow crystal like table salt. Potassium chloride is
easily soluble in water, is hygroscopic and has a caking tendency. This
is a water-soluble quick-release potassium fertilizer.

The raw material of potassium chloride is sylvite or carnallite. Sylvite

is mainly about one-quarter potassium chloride and three-quarters sodium
chloride, table salt. These two chemicals have different solubilities* in
water, so they can be separated to yield potassium chloride. First, place
sylvite in water and heat to get a saturated solution, which is then
gradually cooled. On decrease in temperature and solubility, potassium
chloride precipitates. However, sodium chloride does not vary much in
solubility because of temperature differences, so the solution remains

not precipitated. Then the potassium chloride erystals are separated

from the solution to yield the end product, potassium chloride. Making
potassium chloride from carnallite also relies on the principle of higher
solubility of magnesium chloride than potassium chloride. Potassium chloride
varies in purity because of different production methods. So-called pure
potassium chloride contains more than 90 percent potassium (including potas-
sium chloride), For potassium chloride used as a fertilizer, the potassium
content is about 50 percent and the crude potassium salt contains 20-30
percent potassium. Potassiumchloride is a physiological acid fertilizer,
containing chlorine and potassium. The crops absorb potassium and only
chlorine radicals remain in the soil just like ammonium chloride in nitrogen
fertilizer staying in the soil after application. The chlorine radical is
disadvantageous to the growth of chlorine-avoiding crops (refer to text
page 23 {translation page 207). If these crops need potassium nutrients,
potassium sulfate or other potassium fertilizers can be used as substitutes.

Footnote*: Solubility in water -- this is the maximum amount of a substance
dissolved in water at a certain temperature and pressure.

-41-



Chapter 2. How a Crop Absorbs Chemical Fertilizer
Section 1. Relationship Between Soil and Fertilizer

Under certain conditions of temperature and hunidity, a seed will sprout buds
and grow once it has been sown into the soil. This is because soil can
store and supply various nutrients required by the crop. Before we can
understand the relationship between soil and fertilizer, we must learn about
soil composition and characteristics and their effect on fertilizing power.

Composition and Funct‘on of Soil

’ The soil is composed of matter in three states: solid, liquid and gas. The
solids are of soil granules and. organic matter. The liquid is the water
solution of various nutrients in the soil. The gas is air, occupying most
of the space between soil granules. All these three states of matter should
coexist in the soil. We cannot imagine either the ground as hard as stone
slate without air space or waterless dry soil bearing crops. In ordinary
soil, soil particles are more than 90 percent. of the solid matter. Soil
characteristics are classified by soil particle size. Soil particles greater
than 0.01 mm are physical sand; soil particles smaller than 0.01 mm are
physical clay. Soil containing much sand is called sandy soil; soil contain-
ing much clay is. called clay loam; soil containing about equal parts of sand
and clay is called loam, the most suitable soil type for ordinary crop growth.

Organic matter is made up of microbes. and remains of animals and plants and
can be as high as several percentage or as low as a few parts per 1000.
Generally, soil with a high organic matter content is comparatively fertile.
Soil applied with enough farmyard manure is often black and oily; this is
because a high content of organic matter is in the soil.

In the soil water there are often nutrients which are necessary and absorbable
by crops. The crop plants constantly absorb these elements during growth

and remove them at harvest time. So these elements gradually become deficient.
Although the solid part of soil can be gradually dissolved to supply some of
the nutrients to the crop, this dissolved amount is much. less than the crop
needs. So fertilizer application is required as a supplement.



Slaked lime is calcium hydroxide; it is made by adding water to quicklime
to get a white powder. Slaked lime is also an alkaline fertilizer.

Limestone is a mineral containing calcium carbonate. Limestone reserves
are large and its distribution is extensive. This is the raw material for
making quicklime. Finely ground limestone powder can also serve as a ferti-
lizer. The finer it is ground, the better is its fertilizing effect.
Powdered limestone is not readily soluble in water so its effect is slow
but persistent. In addition, oyster shells or clam shells can also be
finely ground to be used as fertilizers because their calcium carbonate
content is more than 90 percent.

Here are precautions for applying lime:
(1) Lime should mainly be applied to acid and never alkaline soils.

(2) Ordinarily, lime is used as a basic fertilizer. The best application
time is 10 days before sowing. Application should be even and sometimes a
“plow is used to rake the soil evenly after application.

(3) Lime should not be applied each year and the amount used not too high;
otherwise, the microbes generated will decompose too much organic matter,
leading to infertile soil. This is called “exhaustion” of fertility and is
contrary to soil conservation.

2. Gypsum: it is called calcium sulfate. Gypsum's main function is improving
soil characteristics and structure and supplying calcium and sulfur to the
erop. In South China, gypsum has long been applied to paddy field.

There are three types of gypsum. in agriculture: common gypsum, snow white
gypsum and phosphorus-containing gypsum. Natural gypsum ore is crystalline,
ground finely to yield the common gypsum. -It is white or grayish white,
slightly soluble in water. By heating and calcining the common gypsum,
water of crystallization is removed to yield snow white gypsum, a white
powder. Phosphorus-containing gypsum is a residue after decomposing phos-
phate rock by sulfuric acid for making phosphoric acid. Phosphorus-
containing gypsum can also be applied as a fertilizer but experiments

must precede application and acceptance.

If gypsum is used to provide calcium and sulfur nutrients to soils and crops,
the amount used should not be too high, usually 4-6 chin per mou. If gypsum
is used to improve soil, the amount used should be as high as 200 chin per
mou, depending on soil characteristics. Gypsum need not be applied every
year.

3. Copperas: it is called ferrous sulfate -- a green crystal. Copperas is
a@ by-product when iron pyrite is used to refine sulfur; it contains iron
and sulfur. Iron can promote the formation of chlorophyll and crop. growth
and sulfur is a protein component. So these two are elements necessary to
crop growth. Copperas is customarily applied in areas like Shansi, Chekiang
and Hunan with good effects.

-5l-



2. Manganese fertilizer: the main functions of manganese are to promote
germination of seeds and growing of young seedlings. In addition, manganese
can increase photosynthesis and promote metabolism. Manganese deficiency
hampers crop growth and causes diseases. The manganese content in soil is
approximately 0.1 percent, which is higher than that of boron. However, in
soils to which large amounts of lime are applied or in calcareous soil,
frequently manganese cannot be absorbed by crops. Therefore, more manganese
fertilizer is necessary here.

Common manganese fertilizers are manganese sulfate and manganese ore slag.
Manganese sulfate consists of pink crystals, readily soluble in water. It
is 24.6 percent manganese.

Manganese ore slag has 12-22 percent manganese and is insoluble in water.
During application, the amount of manganese sulfate should be small, usually
2-5 chin per mou. The amount of manganese ore slag is 20-40 chin per mou
since its water-soluble manganese content is low.

3. Copper fertilizer: the main function of copper is promoting crop respira-
tion for more germination and good tassel growth. Copper can also raise
crop cold-hardiness. Copper's functions are quite pronounced in cereal
erops and legumes. In a copper deficiency, leaves wither, tassels do not
sprout and the crop yield suffers.

Commonly, copper sulfate or copper ore slag is used as the copper fertilizer.
Copper sulfate consists of blue crystal, is easily soluble in water and has
25-26 percent copper. Copper ore slag is a by-product of copper refining
and contains less copper than does copper sulfate. During fertilizer appli-
cation, generally 2-4 chin copper sulfate per mou is enough but the amount
of copper ore slag should be properly increased.

4. Zine fertilizer: zinc's main function is promoting crop respiration and
growth. If there is a zinc deficiency, grayish green spots will appear on
the leaves of the wheat plant.

Usually, ammonium molybdate is used as a molybdenum fertilizer: it consists
of white crystals. The fertilizer contains 50 percent molybdenum and 6 per-
_cent nitrogen and can be used as a follow-up fertilizer or a seed fertilizer.

All theabove-mentioned trace element fertilizers are best used as a follow-up
fertilizer outside roots. Alternatively, the fertilizers can be used to mix
and soak with seeds. Boric acid can be compounded into a solution of boric
acid, 0.1-0.15 percent in concentration. Manganese sulfate and copper sul-
fate can be compounded into a 0.1 percent water solution; zinc sulfate can

be compounded into a 0.05-0.15 percent water solution for spraying application
on leaf surfaces. The amount used is 50-100 chin per mou for a total of

two to four times of application.

The amount of trace element fertilizer used should be appropriate and if
in excess, waste and sometimes even toxicity will result.

- hg -



Storage warehouses should be well ventilated and leaking roofs repaired on
time; these warehouses should have an elevated foundation and drainage
ditches for removing rainwater. Chemical fertilizers should not be stored
on a muddy floor; they should be raised on brick or wooden supports. Some
bulk chemical fertilizer, such as pulverized phosphate rock and Thomas
meal, can be placed outdoors but protection against rain should be provided.

Section 2 Prevention of Decomposition and Evaporation

Generally speaking, phosphorus fertilizer, potassium fertilizer, trace
element fertilizer and some nitrogen fertilizer are comparatively stable,
such as Ca-Mg-phosphate, potassium sulfate and urea. However, some other
nitrogen fertilizers, like ammonium bicarbonate, will decompose at normal
temperatures; the higher the temperature and the higher the water content,
the faster the decomposition. Other nitrogen fertilizers, like aqua
ammonia, will evaporate at normal temperatures; the higher the temperature,
the faster the evaporation. Packages should be well sealed for less
stable chemical fertilizers --. plastic bags or multilayer kraft paper, bags
should be used. When an irritating ammonia odor is detected, this means
the decomposition of fertilizer is underway due to bag leaking. The bag
should be mended or some other container should be used. Aqua ammonia
should be contained in a well-sealed drum, jug or jar. Clay or gypsum
should be used as a filler to seal the cover.

Ambient temperatures should not be too high during transportation and
storage. Direct exposure to sunlight should be avoided during transportation.
Store the fertilizer in the shade. If aqua ammonia. is stored outdoor with-
out shading, containers will be ruptured through explosion due to thermal
expansion.

Section 3. Prevention of Fire and Explosion

Ammonium nitrate and potassium nitrate tend to explode, causing great losses.
Therefore, strict attention should be paid during transportation and storage.
No smoking should be a strict rule in the vehicle or boat and warehouse.
Direct sun exposure and violent collision should be avoided. During storage,
the fertilizers should not be placed close to flammables, such as gasoline,
diesel oil, kerosene, alcohol, sulfur, firewood and oil paper. Fire-
fighting equipment should be kept in the warehouse. The residual ammonium
nitrate and potassium nitrate should be well stored and attention should

be given not to keep them near heat sources.

Section 4 Corrosion Prevention
Liquid fertilizers, like aqua ammonia, are corrosive, especially so to iron

and copper. So corrosionproof containers are required for these corrosive
fertilizers. Iron or copper containers should not be used for aqua ammonia;

- 55 -



5. Place the sample to be heated over a thin iron sheet. If it melts
quickly and is illuminating and catches fire when thrown on redhot charcoal
and an ammonia odor is released, this sample is urea,

These methods can be alternated or repeated for rapid determination. For
example, for a certain chemical fertilizer one can first use the water
solubility method and if one part is soluble and the rest precipitates,

the sample can then be mixed with lime. If an ammonia odor is released, the
sample is ammonium calcium nitrate. If the sample tastes sour and astrin-
gent, it is calcium superphosphate. If the sample is insoluble and all

of itpreipitates, then by observation of its appearance one can determine
that it is Ca-Mg-phosphate, precipitated phosphate or defluorinated phos-
phate fertilizer.

This is the simple way of distinguishing chemical fertilizers. This is
only for distinguishing fertilizer types. If nutrient content is in ques-
tion, then quantitative analysis should be done in a chemical laboratory.
To systematize these methods, the following table presents a simple determi-
nation technique for the principal fertilizers:

Type of chem- Mixing with External
ical ferti- Appearance Solubility lime Heating, com- observation
lizer bustion after other
processes

Ammonium sul- completely ammonia not melting,
fate soluble odor not combustible

but with ammo-

nia odor
Ammonium completely ammonia fast melting
nitrate soluble odor and release of

white smoke
with ammonia

odor
Ammonium white crys- completely ammonia quick decompo-
bicarbonate tals with soluble odor sition
ammonia
odor
Ammonium completely ammonia not melting, re-
chloride soluble odor lease of white

smoke with ammo-
nia odor and
taste of hydro-
chloric acid

lable continued on following page/

-59-



3. Ammonium calcium superphosphate: like calcium superphosphate, ammoniun
calcium superphosphate is a water-soluble quick-release composite fertilizer.
The fertilizer is manufactured by ammonia reaction with free acid in calcium
superphosphate. hus, the disadvantage of calciun superphosphate due to

its free acid content, which corrodes packaging material and harms crop
growth, can be overcome. In addition, nitrogen nutrient is added. So ammo-
nium calcium superphosphate is an improved version of calcium superphosphate.
Ammonium calcium superphosphate has 16-18 percent phosphorus and 2-3 percent
nitrogen. The application technique and amount are similar to calcium
superphosphate.

4, Potassium-nitrogen mixed fertilizer: this is a mixed fertilizer of nitrogen
and potassium nutrients. In manufacturing, alum stone is heated and added

to aqua ammonia for precipitation and removal of aluminum. Then the end
product results from evaporation and crystallization. This is a white

powder, water soluble. Potassium-nitrogen mixed fertilizer contains appro-
ximately 69 percent ammonium sulfate, with a converted nitrogen content of
13-14 percent and approximately 31 percent potassium sulfate, with a converted
potassium content of 15-16 percent. The fertilizer does not easily cake or
absorb water and has a fertilizing effect in all soils and crops, especially
crops requiring potassium, like tubers, tobacco and hemp. The application
method is the same as with ammonium sulfate, with an amount of 15-30 chin

per mou.

The characteristics of potassium-nitrogen mixed fertilizer are. like those of
ammonium sulfate, to be applied to acid soils. Lime should be coordinated,
but not mixed, in application to prevent soil caking.

For the fertilizing effect of potassium-nitrogen mixed fertilizer, 2 chin

of mixed fertilizer equals 1.2 chin ammonium sulfate as to nitrogen nutrient;
2.5 chin of mixed fertilizer equals 1 chin potassium sulfate as to potassium
nutrient.

Besides these composite fertilizers and mixed fertilizer, we can turn to
the nutritional requirements of crops when compounding mixed fertilizers by
different nitrogen, phosphorus and potassium content. Section 7 "Mixed
Application of Fertilizers" of this chapter will recommend feasibilities

of mixing fertilizer types.

Section 5 Trace Element Fertilizers

As described above, three main types of fertilizers have been enumerated:
nitrogen, phosphorus and potassium fertilizers. These are fertilizers in
heavy demand through artificial means. Besides nitrogen, phosphorus and
potassium, there are dozens of different chemical elements essential to
roots, stems, leaves and fruits of a crop plant from analyses and studies
of scientific observations. Although the amount of some elements are in
the micro-range, they are necessary to crop growth and maturation. Like
the human body, besides needing large amounts of fat, protein and

-AT-



Since making ammonium bicarbonate is simple and plant construction is rapid,
capital investment is low and its costs are low. The fertilizer can be
extensively used in various crops and soils with good fertilizing effect.
So ammonium bicarbonate output is climbing rapidly in China.

Ammonium bicarbonate can be used either as follow-up fertilizer or as basic
fertilizer, but it should not be used as seed fertilizer. It is best to
make ditch or hill application of dry ammonium bicarbonate; the application
depth into the soil should be deep and covered with soil immediately after-
wards to avoid the evaporation and loss of nutrients. Or, 30 to 50 times
of water by weight can be mixed with the fertilizer for spraying or ditch
application and immediately covered with soil. Or, five to ten times of
fine dry soil can be mixed with the fertilizer for deep application and
covered immediately with soil. The quantity of ammonium bicarbonate applied
is generally 18 percent more than that for ammonium sulfate, with 20-60
chin per mou.

Ammonium bicarbonate can be applied to various crops. For paddy rice,
seedling fields or fields after seedling transplanting can be treated with
the fertilizer. One single application can be adopted as the basic ferti- ’
lizer or multiple applications as the follow-up fertilizer. For wheat
plant, ammonium bicarbonate can be used as the follow-up fertilizer during
periods of sprouting, return-to-green, node sprouting and tassel incubation.
For use on corn plant, the fertilizer can be used as follow-up fertilizer
in the period after seedling transplanting. to sprouting of male tassel.
Application can be made in the time between seedling and incubation of
unopened flower buds, flowering period, or even vigorous growing period of
bolls for cotton. Each application is between 10 and 20 chin.

Here are precautions for applying ammonium bicarbonate:

(1) Since ammonium bicarbonate is highly volatile, packages should be well
sealed whether in transportation, storage or before application. Usually,
plastic bags are used for packaging. During application, it is best to open
the next package only after using up the previous one. Fasten the package
tightly if there is some fertilizer left, or the plastic bag can be covered
by a pot or earthenware jar to prevent evaporation.

(2) Application conducted for ammonium bicarbonate should be by ditches or
hills then covered with soil right away. It is forbidden to spread on the
soil surface, otherwise all nutrients will escape into the atmosphere or
even cause chemical etching injury to crop stems and leaves.

(3) Ammonium bicarbonate should not be mixed with farmyard manure to make
compost, or even mixed with lime or other alkaline fertilizers, such as
calcium cyanamide and pearl ash. The yield-increase effect of ammonium
bicarbonate is 3.5-4.5 chin of paddy rice per chin of fertilizer. The
fertilizing effect is generally higher than with ammonium sulfate for
applying same quantity of nitrogen per mou.

-19-



fertilizing effect of Ca-Mg-phosphate in Kiangsi Province, the yield gain
is 60-80 percent for Tacoma grandiflora, Loisel, 10-23 percent for paddy
rice, 30 percent for cotton and over 60 percent for wheat. From paddy rice
experiments at Chin-hua County of Chekiang Province, the fertilizing effect
of Ca-Mg-phosphate is 110 percent of calcium superphosphate. From corn
experiments at Kweiyang, Kweichow Province, the fertilizing effect is 108.6
percent of that of calcium superphosphate. These experiments show that
Ca-Mg-phosphate is a good phosphorus fertilizer that can be vigorously
propagated.

4, Thomas meal: this fertilizer gained its name because it was first manu-
factured in a Thomas steel-smelting furnace. The fertilizer is a steel
smelting by-product. In an alkaline steel-smelting furnace, impurities

like phosphorus, lime and calcium silicate become slag floating on liquid
steel. This slag is then poured out and the end product is obtained after
cooling, grinding, magnetic dressing and packaging. In the magnetic dressing
process, steel particles are removed. Thomas meal is a desirable fertilizer
type since it is a steel smelting by-product and the Chinese iron and steel
industry has seen great growth.

Thomas meal resembles fly ash under a cooking pot. It is a blackish brown
powder, about 16 percent phosphorus. Also, there are mostly lime content

as well as amounts of magnesium, iron, silicon, sulfur, molybdenum, vanadium
and cobalt. The specific gravity of the fertilizer is high. In some area,
the peasants called it “iron crumbs", but actually the fertilizer contains
little iron.

Thomas meal is an alkaline chemical fertilizer; this is a citric~acid-soluble
phosphate fertilizer, suitably applied to acid soils. The fertilizing effect
is slower than others; the fertilizer is usually applied as basic fertilizer,
unsuited as follow-up or seed fertilizer. Before application, Thomas meal
can be mixed and piled with barnyard manure for a better fertilizing effect.
Thomas meal contains large amounts of lime and it can promote decomposi-
tion of compost and the organic acid content in the compost can promote
phosphorus decomposition in the fertilizer to become a quick-release ferti-
lizer. The fertilizer is appropriately applied to soybean, cotton, corn

and paddy rice. When Thomas meal is used, the fertilizing effects are good
in clayey, acid, lowland or irrigated soils but less so in sandy, alkaline
and upland soils where irrigation is infeasible. For application in upland
soils, the fertilizer should be plowed into deep soil. Dry application is
acceptable, but not wet application. Spraying application is feasible.
Usually, the amount of Thomas meal used is 30-60 chin per mou.

The yield-gain effect of Thomas meal is 3-23 percent for paddy rice, 10-100
percent for corn, 15 percent for sorghum, 24-46 percent for millet, 5-27
percent for soybean or 9 percent for cotton. In Manchuria, application in
lowland fields led to a mean yield gain of about 10 percent and in upland
fields, of about 5 percent. Thomas meal can have fertility persisting for
several years. Moreover, the fertilizer can raise the oil content of soybean
and sunflower seed, the starch content in paddy rice and sugar content in
sugar beet.

-37-



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PUBLICATION DATA

: ESSENTIALS OF CHEMICAL FERTILIZER

USE IN PRC

: SHIH-YUNG HUA-HSUEH FEI-LIAO TI
I-PAN CHIH-SHIH

: Wang Nai-ch'iang [3769 0035 1730]

: Fuel and Chemical Industry Publishing

Service, No 16 Ho-p'ing-pei Road,
outside of An-ting Gate, Peking
(based on the original matrix of the
former Chemical Industry Publishing
Service)

: Second Printing Plant of the Fuel and

Chemical Industry Publishing Service

: Sold by New China Book Store, Peking
: Peking

: August 1974

+ 216,050

: 15063°1012 (Hua-211)

52,000

: 787x1092 in thirty-two mo
: 2 3/8

: 0.16 yuan



young seedlings. Of course, calcium cyanamide cannot be used as a seed
dressing. In lowland fields, calcium cyanamide should be applied before
seedling are transplanted, with about 1 ts'un of irrigation water kept in
the field. The fertilizer can be sprayed or mixed with stable manure and
compost for spraying application to be uniformly distributed and overturned
into the soil. Then sowing can follow 10-15 days later. If calcium cyanamide
is used as follow-up fertilizer, it should be uniformly mixed with 10 parts
dry soil and barnyard manure to be piled and macerated 10-15 days. After
the compost is ready, it is then ditch-applied to bury the manure in the
soil. However, care should be taken that the piling time is not too long
after the calcium cyanamide and compost are mixed. Otherwise, the nitrogen
nutrient will be reduced.

The amount of calcium cyanamide applied is usually 20-40 chin per mou.
Here are precautions for applying calcium cyanamide:

(1) Calcium cyanamide is toxic to both man and animals, therefore movth

masks should be worn during application to avoid harming the respiratory
organs. In addition, the operator should wear gloves and goggles. A short -
rod can be used to stir calcium cyanamide, dry soil and farmyard manure to
avoid hand contact and later chemical burns. Ground areas piled with

calcium cyanamide should be swept clean to keep animals from being poisoned
by eating the fertilizer dust.

(2) Calcium cyanamide is highly hygroscopic. On contacting water, it cakes
and swells. Caked calcium cyanamide should be crushed before application.
When crushing, strokes should be light to avoid scattering dust. Tools
should be washed clean after use. When mixed with much water, calcium
cyanamide gives off heat and a bad odor. Thus, some of its fertility is
lost. So it should be protected against moisture. If calcium cyanamide
contacts water, it should not be dried out under the sun.

(3) Calcium cyanamide cannot be allowed to contact seeds and seedlings, to
avoid chemical injury.

(4) It is best not to use calcium cyanamide in very arid area that cannot
be irrigated.

(5) Calcium cyanamide should not be mixed with ammonium sulfate, ammonium
nitrate or calcium superphosphate to be applied. Otherwise, the nitrogen
nutrient in ammonium sulfate or ammonium nitrate will be lost, or the phos-
phorus content in calcium superphosphate be excessively reduced.

The yield-gain effect of calcium cyanamide is like that of ammonium sulfate.
In acid soil, the fertilizing effect of calcium cyanamide is superior to
that of ammonium sulfate. From work at Japanese agricultural experimental
stations, sometimes the fertilizing effect on paddy rice is 5 percent higher
than for ammonium sulfate. Though calcium cyanamide is not widely used

in China, comparison experiments were made in Chekiang and Fukien provinces,

- 30-



(2) Ammonium sulfate should be mixed with alkaline fertilizer, such as
pearl ash, calcium cyanamide or Thomas phosphate. If mixed before applica-
tion, ammonium sulfate will be decomposed with the loss of nitrogen. Alter-
nate application is desirable.

(3) When applying ammonium sulfate, care should be taken not to let it stick
to stems and leaves of the crop plant, otherwise the crop will exhaust its
vitality due to excessive growth. When applying fertilizer, the proper dis-
tance should be kept from crop roots. It is best to conduct furrow or hill
application in the space between two adjacent planting rows. Or else applica-
tion is conducted by digging a ditch and then covered with soil after applica-
tion. If the ammonium sulfate is dissolved in water for application, one
chin of ammonium sulfate can be mixed with 30-50 chin of water. If dry soil
is mixed with the fertilizer, one chin of ammonium sulfate can be mixed

with 5-10 chin of dry, fine soil.

(4) Hygroseopicity of ammonium sulfate is low. However, since the fertilizer

‘contains a small amount of free sulfuric acid, sometimes it can be moistened

and cake. This does not affect fertilizing power. During application,
caked ammonium sulfate can be crushed by knocking or applying pressure.

The output-increase effect of ammonium sulfate is as follows: one chin of
ammonium sulfate can approximately increase yield of paddy rice by 4-5 chin,
wheat by 2-3 chin, corn by 4-6 chin and unginned cotton by 1.5-3 chin. The
fertilizing effect to other crops is also considerable.

2. Ammonium nitrate: it is white granules or powder. When containing impu-
rities, the fertilizer sometimes is gray or light yellow. Granularity of
ammonium nitrate is similar to that of ammonium sulfate. This fertilizer
has rapidly developed in use in China in recent years, with large outputs.

The nitrogen content of ammonium nitrate is higher than in ammonium sulfate,
about 34-35 percent. This is a highly effective nitrogen fertilizer. One
chin of ammonium nitrate is equivalent to 1.75 chin of ammonium sulfate,
therefore less can be applied than for ammonium sulfate. If 10 chin of
ammonium sulfate is required per mou of farmland, then 6 chin of ammonium
nitrate should be applied.

‘The water solution of ammonium nitrate is neutral, but after its application

into the soil, nitric acid forms via bacterial reaction. Therefore, this is
a physiological acidic chemical fertilizer. However, it is less acid than
ammonium sulfate. In addition, nitric acid can be converted and be absorbed
by the crop, then the acidity naturally disappears. So this is a fertilizer
of nearly neutral reaction and can be adapted to various soil types. The
fertilizing effect is concentrated and fast and causes significant output
increase to grain crops, cash crops, fruit trees and vegetables. The ferti-
lizer can be also applied in either upland or lowland field, yet the ferti-
lizing effect on upland field is better. If ammonium nitrate is applied in
paddy fields, the fertilizing power is little less than for ammonium sulfate
with equivalent amounts of nitrogen. From experiments in Kiangsu Province,

-16-



Urea is a white or light yellow needle-shaped or prismatic crystal. The
industrial. product is powdered or granulated crystals. Some cold feeling
willeppear if urea is placed on the tip of the tongue because urea absorbs
heat as it dissolves. Urea contains 45-56 percent of nitrogen; this is one
of the highest nitrogen-containing chemical fertilizers.

The nitrogen content of 1 chin of urea is equivalent to 2.2 chin of ammonium
sulfate, 1.3 chin of ammonium nitrate, 1.8 chin of ammonium chloride or 2.6
chin of ammonium bicarbonate. In addition to nitrogen content, urea also
contains carbon dioxide which can also be absorbed by crops after decomposi-
tion in soil, promoting photosynthesis. This feature is the same as for
ammonium bicarbonate.

Urea also contains about 1 percent semicarbazones, a substance harmful to
crop growth. By experiments, when the semicarbazones content exceeds 3 per-
cent in urea, absorption by root system for seed sprouting will be affected.
This problem has been noted in industrial production, so agricultural urea
does not contain much semicarbazones. .

Urea can be used as follow-up or basic fertilizer but not as seed fertilizer. .
As basic fertilizer, it is best to mix urea with farmyard manure before
application.. When used as follow-up fertilizer, either dry or wet applica-
tion is allowed. During dry application, urea can be mixed with 8-10 times
fine dry soil and during wet application it can be mixed with 80-100 times

of water in spraying application. Generally, 7-25 chin of urea can be

applied per mou of farmland.

Urea is hygroscopic so it dissolves easily in water. It is a neutral ferti-
lizer adaptable to a variety of soils and crops. It does no damage to soil
even after long-time application. Urea does not remain as a residue in the
soil. Generally, the fertilizing effect of urea is 3-5 days slower than
ammonium sulfate. Although the fertilizing effect is a little slower yet
the effect is persistent. Urea dissolves at different rates when applied
in soils of different characteristics. It ‘dissolves faster in neutral and
alkaline soils than in acid soils. Urea dissolves faster in clay loam than
in sandy soil. After decomposition, the chemical nutrient easily adheres
to. soil and is not likely to be leached.

* Urea can also be applied outside roots or on leaf surfaces. This can be
done by spraying urea solution on crop leaf surfaces so that the solution
can infiltrate into leaf cells for photosynthesis in making sugar compounds,
amino acids and finally protein. The crop absorbs nutrient faster if applied
externally to roots, starting to absorb as early as 5 hours after spraying
and absorbing 50-75 percent after 24 hours spraying with fertilizing power
persisting about 7-10 days. So when applying urea outside roots, it is
better to spray every 7-10 days. Usually, fertilizer application outside
roots is used in these cases:

(1) applied to creeping crops of fruits or melons;

- 22-



avoid overapplication to cause excessive growth, late ripening and chemical |
etching injury by direct contact with stems, leaves or roots.

(3) Ammonium nitrate should be mixed with alkaline fertilizer before applica
tion, otherwise partial decomposition will occur, causing nitrogen loss.

The yield increases from ammonium nitrate use are 3-5 chin of wheat, 2.5-5
chin of cotton or 6-10 chin of corn per chin of fertilizer applied.

3. Ammonium bicarbonate: it is a white crystalline powder but sometimes it

is grayish white due to impurities. The fertilizer has a bad odor like that
of ammonia; it has 17.5 percent nitrogen. Its solution is nearly neutral.

No residue will remain after soil use, so the fertilizer does not cause soil
to deteriorate. Therefore, a number of soil varieties can be treated with it.
The fertilizer decomposes rapidly after applied to soil and it can be
rapidly absorbed by crops. After decomposition, not only can nitrogen be
used as fertilizer, but the other decomposed product, carbon dioxide, also
benefits crops, such as promoting photosynthesis and adding chlorophyll
content. So ammonium bicarbonate is a desirable nitrogen chemical ferti-
lizer. ’

Ammonium bicarbonate has a drawback: it is unstable and easily decomposed.
At 20°C, dry ammonium bicarbonate is fairly stable. However, when tempera-
tures are high, or the water content in the fertilizer is high, it can
decompose into ammonia and carbon dioxide, which are d‘ssipated into the
atmosphere. The higher the temperature and water content, the faster the
decomposition. From experiments, for an ammonium bicarbonate sample with
the same water content and stored for 100 days, losses are 2.5 percent in
winter but 25 percent in summer. The difference in loss is tenfold.
Similerly, for dry ammonium bicarbonate at 20 to 30°C and stored 12 days,
decomposition is only 4.8 percert. If the fertilizer contains 4.8 percent
water, almost all ammonium bicarbonate disappears in 12 days. In moist
atmosphere, the fertilizer will absorb moisture and decompose. This
constant decomposition appears as a strong irritating ammonia odor. This
problem can be taken care of by tightly sealing bags. Otherwise, the volume
of fertilizer will be reduced gradually in the warehouse by escaping into
the atmosphere.

Although ammonium bicarbonate has the failing of constant decomposition
into the atmosphere, yet losses can be considerably cut back by packaging
with plastic bags or other sealing container. Also, ammonium bicarbonate
should be quickly consumed once manufactured.

Ammonium bicarbonate is manufactured by using ammonia and carbon dioxide as
raw materials. Carbon dioxide is a by-product of synthetic ammonia plants
or it can be obtained from a lime kiln. First, ammonia gas is dissolved in
water to form aqua ammonia; this then reacts with carbon dioxide to form
ammonium carbonate, which further absorbs carbon dioxide, to yield ammonium
bicarbonate.

-18-



with good fertilizing effect. From general experience, the fertilizing
effect is better for lowland fields than upland fields, better in acid than
in neutral soil, and better used as basic fertilizer than as follow-up ferti-
lizer.

Section 2. Phosphorus Chemical Fertilizer

Phosphorus is not found in soils in large amounts, generally only 0.05-0.35
percent of total phosphorus /I 7. The percentage of available phosphorus /2 7
absorbable by crops is usually about 30 percent. So supplements should be
applied.

Phosphorus has these functions:

(1) Phosphorus is a constituent of nucleoproteins; it can intensify plant
cell division, for faster crop growth.

(2) Phosphorus aids the growth of crop roots and root hairs. The more numer-
ous the root hairs, the more nutrients and moisture can be absorbed from

the soil.

(3). Phosphorus helps ripen seeds and makes stalks stronger, for added disease
resistance and better fruit quality.

If nitrogen fertilizer is properly applied with phosphorus. fertilizer, crop
yields will be much higher. So applying phosphorus fertilizer is essential.
Here are some problems in applying phosphorus fertilizer:

1. Relationship between soil and the fertilizing effect of phosphorus ferti
lizer: the fertilizing effect is closely related to soil characteristics

and soil fertility. For a few years after cultivation, when soil matura-
tion is low, application of farmyard manure is not sufficient, soil ferti-
lity is low, or where are acid soils or alkaline soils, generally the effects
of phosphorus fertilizer are good. The fertilizing effect is high when phos-
phorus fertilizer is used to treat phosphorus-deficient soils: laterite,
white bentonite colloidal clay and South China's low-yield paddy fields.
Applied to acid soils, phosphorus fertilizer should be coordinated with

lime without mixing the two. In alkaline soils, phosphorus fertilizer
application should be coordinated with farmyard manure.

2. Relationship between crop varieties and fertilizing effect of phosphorus
fertilizer: different crops have different needs and assimilability for
phosphorus content in phosphorus fertilizers. The best effect comes from
applying phosphorus fertilizer to legumes and green-manure crops -- Astragalus

Footnote Lf: Total phosphorus includes assimilable and unassimilable

phosphorus. .
Footnote Le: Available phosphorus is phosphorus that can be assimilated

by the soil.

| - 31-



Chapter 3. Characteristics and Methods of Applying Chemical Fertilizers

There are many types of chemical fertilizers with many classification methods.
However, the most common classification depends on the nutrient content, such
as nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, trace
element fertilizer, composite fertilizer, mixed fertilizer and mineral ferti-
lizer. These fertilizers are introduced in the following:

Section 1. Nitrogen Chemical Fertilizer

Crop growth is cellular growth in the plant body. The important component
of the cells is protein, approximately 16-18 percent nitrogen. This shows
how important nitrogen is to crop growth.

Man gets nitrogen by eating grains and vegetables. In growing, grains ani
vegetables absorb nitrogen from the soil. As. soil nitrogen is depleted by
crops and nitrogen from other sources is leached by irrigation or rain water,
the soil nitrogen becomes insufficient. So nitrogen fertilizer should be
applied to supplement nitrogen in the soil.

Nitrogen is also richly present in the atmosphere, approximately four-fifths
the entire volume of the atmosphere or 76 percent by weight. This nitrogen
is called free nitrogen that the crop cannot absorb directly. After the
nitrogen is embodied in nitrogen compounds, a crop can absorb it.

_ Although a crop should have enough nitrogen fertilizer, is it better to apply

excessive nitrogen fertilizer? No. Like a man who eats food; if he consumes
too little, nutrit‘onal deficiencies will develop. .If he eats too much,
indigestion will follow; this could lead to intestinal and stomach diseases.
If a crop is given too much nitrogen fertilizer, especially uncoordinated
with phosphorus and potassium fertilizers, the crop will grow excessively
and be too green; the stems damp off easily; the crop is easily attacked by
pest; and fruits ripen late without gains in yield. If excessive nitrogen
fertilizer is applied at one time, the crop will exhaust its vitality by
overgrowth. So nitrogen fertilizer should be used properly by crop variety
and growing period. How much nitrogen fertilizer per mou? This depends

on the soil and crop variet’es. From experience in farmyard manure applied
to ordinary soils, 4-10 chin of nitrogen element per mou is a good guide
for main crops, such as paddy rice, wheat, corn and cotton. Converted into
ammonium sulfate, this anount of nitrogen element is about equal to 20-50

-13-



Chapter 5.. Simple Distinguishing Methods of Chemical Fertilizers

From this description it is understood that chemical fertilizers have dif-
ferent characteristics and methods of use. We should rely on their charac-
teristics to rationally store and utilize these fertilizers to exploit
their full fertilizing power and avoid crop loss and harm. If urea is
mistaken for ammonium sulfate, the fertilizer amount used may be too much,
thus wasting urea. If ammonium bicarbonate is mistaken for ammonium
chloride and not well sealed, the fertilizer will decompose and escape
into the environment. If ammonium chloride is mistaken for ammonium
sulfate and applied to a tobacco field, the yield will be lowered. There-
fore, the fertilizer should be correctly recognized before application.

Usually, the name brand is marked on the bags of solid fertilizer. However,
in case of marking damage or mixup of containers, the fertilizer in question
should be correctly recognized. The best way to determine a chemical ferti-
lizer is chemical analysis. Chemical laboratories are quite widespread in
most areas and analysis of samples can determine the correct name brand.
However, in localities without well-equipped laboratories simple methods
should be used with local materials to determine the fertilizer. Here are
suggestion for several ways of recognizing chemical fertilizers without
using any chemical test equipment.

Section 1 Determination From Appearance

Exterior appearance, color and odor of an unknown fertilizer are guides for
determination. For example, calcium cyanamide is a black or grayish black
powder with a carbide odor. Thomas meal is an odorless blackish brown
powder. Ammonium bicarbonate is a white erystal with an irritating ammonia
odor.

Section 2 Water Solubility
If the name brand of a fertilizer cannot be ascertained from its appearance,

water solubility can be used. A glass cup ora porcelain bowl is filled
to the brim with cooling boiled water. A teaspoon of fertilizer sample is

-57-



inorganic fertilizer. Chemical fertilizers can be classified into different
ways.

Classifying by Nuvrients in the Fertilizers

1. Nitrogen chemical fertilizers: common nitrogen fertilizers are ammonium
sulfate, ammonium nitrate, urea, ammonium bicarbonate, ammonium chloride,
aqua ammonia and calcium cyanamide.

2. Phosphorus chemical fertilizers: common phosphorus fertilizers are calcium
superphosphate, Ca-Mg-phosphate, concentrated superphosphate, defluorinated
tricalcium phosphate and Thomas phosphate.

3. Potassium chemical fertilizers: common potassium fertilizers are potassium
sulfate and potassium chloride.

4. Composite and mixed fertilizers: these fertilizers contain two or more
nutritional elements; for example, ammonium phosphate contains nitrogen and
phosphorus, and potassium nitrate, nitrogen and potassium.

5. Trace element fertilizers contain boron, magnesium, copper, manganese,
zinc or molybdenum, by-products for making sodium borate or boric acid, boron
and magnesium; copper sulfate, copper.

6. Indirect fertilizers differ from the above five fertilizers, directly
aiding crop growth by adding to nutrients. Indirect fertilizers improve
soil characteristics, bettering soil conditions for crop growth and supplying
nutrients elements (calcium, magnesium or sulfur). Lime and gypsum are
indirect fertilizers. Most soils in South China are acidic and after long
application of acidic chemical fertilizers, the soil will crust over,
denying crops access to nutrients. After spreading lime on this kind of
soil, the soil tilth will benefit, giving nutrients to crops. Soil microbes
ean also multiply rapidly. Gypsum can improve alkaline soil but applying
such fertilizer should be done heavily. This leads to high costs so the
practice is not generally common over large areas.

Classifying by Rate of Fertilizing Effect

1. Quick-release fertilizer: some chemical fertilizers can quickly dissolve
in soil moisture, so its nutrients are easily absorbed by crops. This is
quick-release fertilizer. All nitrogen fertilizers, superphosphate and
concentrated superphosphate among phosphorus fertilizers and potassium
sulfate and potassium chloride among potassium fertilizers are quick-release
fertilizers. These fertilizers can be follow-up or basic fertilizer, but
are most effective as the former.

2. Delayed-release fertilizers: some chemical fertilizers are poorly dissolved
in soil moisture or else these fertilizers dissolve slowly without apparent
effects in a short period but with persistent fertilizing effect. The delayed-
release fertilizers are Ca-Mg-phosphate, Thomas phosphate and pulverized

-5-



9. Sodium nitrate: it is found as natural sodium nitrate and synthetic
sodium nitrate. The former is mined in Chile, so it is also called Chile
niter. Before ammonia was synthesized, Chile niter was the main nitrogen
fertilizer, about 15 percent nitrogen. Its color may vary: light yellow,
pink or brown, due to impurities. The fertilizer is in granular form.
Synthetic sodium nitrate generally is a by-product of nitric acid manufacture;
it is made by letting soda ash solution absorb the waste gas of nitric acid
manufacture. This waste gas has nitrogen oxide and nitrogen dioxide not
absorbed by the nitric acid. By this method, sodium nitrate is made to
contain sodium nitrate, which can be oxidized by adding dilute nitric acid
to the sodium nitrate. Synthetic sodium nitrate is 15-16 percent nitrogen
and consists of grayish white particles with minute impurities. Sodium
nitrate tastes bitter and astringent and dissolves easily in water. Sodium
nitrate is a physiological alkaline chemical fertilizer. After applied to
soil, the nitrate is converted and absorbed by the crop, the sodium remain~
ing in the soil. It is alkaline in reaction. Sodium nitrate is highly
hygroscopic and cakes easily. It is adaptable to acid soil. It is best
mixed with farmyard manure if applied to alkaline soil. Alternate, sodium
nitrate can be applied by coordination with calcium superphosphate or
potassium sulfate.

Sodium nitrate can be used as basic fertilizer or follow-up fertilizer, but
its fertilizing effect is better as follow-up fertilizer. It can be applied
dry or wet. Dry, the fertilizer can be mixed with five to six parts fine,
dry soil. Wet, it can be mixed with 40 to 50 parts water. The amount is
15-50 chin per mou, especially for root crops, like sugar beet and turnip,
to promote starch formation. However, sodium nitrate is unsuited to saline
alkali soil.

The fertilizing effect of 1.5 chin sodium nitrate is about equal to 1 chin
ammonium sulfate. Application in clay loam should be limited to avoid soil
deterioration.

Here are precautions when applying sodium nitrate:

(1) Sodium nitrate poisons farm animals, so they should be kept from mis-
takenly eating the fertilizer.

(2) Sodium nitrate is highly hygroscopic so it should be kept dry to avoiding
caking. Lightly crush any caked fertilizer with a wooden hammer, just as in
crushing sodium nitrate, to prevent explosions.

(3) Sodium nitrate is easily combustible and explosive, so fire prevention
practices need’ to be watched in storage and transportation.

10. Calcium cyanamide: it is a nitrogen fertilizer used for quite a long

time. Conversely to ammonium sulfate, calcium cyanamide is an alkaline
fertilizer because it contains calcium beneficial to acid soils.

- 28 -



iit | C SADE it GL BIUeIe, Sie, re

a oy
nae > 2 3 | 4 C4) 6(33 7 8
10 20.0 | 30.0 | 40.0 150.0 {60.0 70.0} 80.0
12 16.7 | 25.0 | 33.3 141.7 [50.0 58.4] 66.7
44 14.3 | 21.4 | 28.6 135.7 42.9 50.0] 87.2
16 12.5 | 18.7 | 25.0 [31.3 (37.5 43.8 | 50.0
92] fanaa | 16,7] 22.2 27.8 [3.3022 | 30.9) ated
20013 10.0 | 15.0 | 20.0 25.001 j30.0 35.0] 40.0
22” 9.1 | 13.6 | 18.2 (22.6 (97.3 31.8] 36.4
24 8.3 | 12.4 | 16.6 [20.8 24.9 29.2 | 33.3
30 | 6.6} 10.0 13.3 16.6 20.0 23.3 | 26.6
32 6.2] 9.3] 12.4 f15.6 118.7 21.9 | 24.8
341,03) 5.9} 8.8 | 11.8 (14.701) |17,703) 20.6 | 23.6
4. 5.0 | 7.51 10.0 |t2.5 [15.0 17.5 | 20.0
a 4.5 | 6.8] 9.1 |t14 — {13.6 15.7 | 18.2
46(12,(21,031 | 4.3 | 6.5} 8.7 [10.9C1) 13.6623, (33) 15.2) 17.4
soC43 4.0 | 6.0} 8.0 |10.0C42 |12.0 14.0 | 16.0

Remark: The bracketed figures in the table show
the number of the particular example
referred to.

Key:

a. Amount of fertilizer used in chin per mou

b. Nutrient content, percent

¢. Amount of pure nutrient used (nitrogen, phos-

phorus pentoxide, potassium oxide), chin per
nou :

Here are examples:

(Example 1) The amount of ammonium sulfate used is 25 chin per mou as
the fertilizing norm. If ammonium nitrate or urea is now used, how many
chin should be applied?

Referring to this table, the nitrogen nutrient content in ammonium sulfate
is 20 percent (neglecting decimals) and in the "amount of fertilizer used"
column locate the figure 20, then trace rightward to the figure 25 (the
amount of ammonium sulfate used in chin). Then trace downward to the
figure 34 (ammonium nitrate contains 34 percent nitrogen nutrient) and
trace parallel to 14.7; that is, 14.7 chin of ammonium nitrate should be
applied. Similarly, trace downward from 25 to 46 in the ‘bmount of fertilizer
used" column (urea contains 45 percent nitrogen nutrient) and then parallel
to 10.9. That is, 10.9 chin of urea should be applied per mou.



production costs are low; the raw materials are ammonia, water and a little
carbon dioxide. Volatility losses of carbonated ammonia are smaller than
for aqua ammonia. Especially in the case of small chemical fertilizer
plants, making carbonated aqua ammonia means savings and convenience for
use near the plant. Aqua ammonia and carbonizing ammonia were developed
rapidly in recent years in China. These products receive ready acceptance
by peasants.

Aqua ammonia is a colorless liquid like water. However, one should not apply
aqua ammonia like irrigation water, else the crop will be chemically etched
then die. Ordinarily aqua ammonia is diluted with water before used: gener-
ally with 30-50 times of water. If the soil is moistened, the dilution ratio
ean be smaller.

Aqua ammonia can be used as follow-up or basic fertilizer. Ditch or hill
application is best in.upland fields at depths of 2-3 ts'un. After the ferti-
lizer is applied, the place should be covered with soil to avoid evaporation.
In spraying, aqua ammonia is diluted with 150 times of water, but it is not
allowed to splash it onto the soil. Usually this fertilizer solution is
mixed with irrigation water for a homogeneous application. Two ts'un of irri-,
gation water should be left in the field to avoid fertilizer losses or to
avoid chemical etching damage to crops. In some area, aqua ammonia-filled
pots or jars are placed on raised field partitions and a rubber hose feeds
aqua ammonia on the siphon principle into the irrigation ditch. Then the
fertilizer can be spread with irrigation water through the entire field.

If weeding follows, the fertilizing effect is even better. The amount of
aqua ammonia applied to each mou is about 20-60 chin, 20 percent more than
the amount of ammonium sulfate used.

Application of aqua ammonia in lowland fields can keep pest insects out and _
its application in wheat fields can prevent and treat wheat blight. This can

have two purposes.
Here are precautions for applying aqua ammonia:

(1) Since aqua ammonia is liquid, its transportation and packaging is not as
convenient as with a solid. Its containers must be sealed due to its
volatility. If it no longer has a bad odor, its nutrient value is zero.

(2) In applying, the aqua ammonia concentration should be kept constant. Too
low a concentration will result in low fertilizing effect and too high a
concentration, chemical etching of crops.

(3) In lowland fields, irrigation water should not be immediately drained
after fertilizer application. Otherwise, fertility will be lost.

(4) Aqua ammonia is corrosive, especially so to copper. So copper containers
should never be used. Crop seeds should not be allowed to touch aqua
ammonia, to avoid affecting sprouting. Stems and leaves must also not be
allowed to contact the fertilizer, to avoid chemical etching. One's hands

- 25 -



Nitrogen, phosphorus, potassium, sulfur, calcium, magnesium and iron have
different. functions in crops.

Nitrogen is a vital element in forming protein, the main component of plant
cells. Nitrogen-deficient crops will have small, withered stems and leaves
with undesirable growth. If the nitrogen supply is severely hampered, the
crop will then wither and die.

’ Phosphorus is the main element constituting fruits and seeds. In phosphorus-

/

deficient soil, seeds will not bear roots and bud; leaves curl and are easily
shed. Sometime, red, purple or brown spots appear on leaves bearing small
fruits and hollow seeds.

Potassium increases resistance to crop diseases and promotes metabolism; these
functions benefit the formation of carbohydrates and proteins for strong,
firm stems and leaves, preventing collapse. Potassium-deficient signs of a
erop are initially withering leaves then thin stems eventually.

Magnesium and iron are necessary in forming chlorophyll. Sulfur helps forn
protein in the plant body, especially in scallions and garlic. Sulfur is a ,
nutrient for root nodule bacteria, indirectly aided a crop's absorption of
nitrogen from the atmosphere. Calcium especially aids in adjusting physio-
logical functions and improving soil characteristics. This is why lime is
applied to soil in some parts of South China.

Some elements, like copper, manganese, molybdenum, boron and zinc, promote
erop metabolism; some elements help crop respiration; and some elements greatly
activate nitrogen-fixing bacteria.

Crops require many chemical elements, serving different functions in crops,
therefore we should meet the crop requirements for deficient elements. As
stated, carbon, hydrogen and oxygen come from the atmosphere and water.
Enough calcium, magnesium, sulfur and iron in soil generally are present for
crop absorption; only in rainy South China should calcium be supplemented
because it is easily leached. Crops require only little boron, manganese,
copper and zine so these elements generally are absorbed from the soil with
occasional supplement from outside sources. Not so for nitrogen, phosphorus
and potassium. Although there are some of these elements in soil, the
amounts are insufficient. Moreover, most nitrogen, phosphorus and potassium
are used up at crop harvest. Constant supplement of these elements is a must.
So the supply of nitrogen, phosphorus and potassium through fertilizer
application is vital. These three elements are called the three elements of
fertilizer.

There are many types of fertilizer: human feces and urine, manure of domestic
animals and fowls, decayed animals and plants, rapeseed cake, urban sewage,
river mud, garbage and young, tender green-manure crops. In addition to
nitrogen, phosphorus and potassium, these fertilizers contain organic matter
and sometime compounds of sulfur, boron, copper and zinc. So these fertilizers
are called farmyard manure.



[Text] Summary

This book briefly introduces the characteristics and application methods of
various nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers,
composite fertilizers, mixed fertilizers, trace element fertilizers and other
mineral fertilizers. In addition, the problems of packaging, transportation
and storage are also described. This helps in understanding the application
and basics of chemical fertilizers by comrades of the related units.

This book can be read by rural commune cadres, intellectually oriented youth
and agricultural technicians. It may also be used as a reference by the
appropriate comrades of chemical fertilizer plants and sales departments.

Chapter 1. What Are Chemical Fertilizers?

Section 1. Functions of Fertilizer

Like the food people eat, crops absorb all kinds of nutrients for growth.
Long-term production practice and scientific experiment has shown that there
are about 60 to 70 nutrients needed in various amounts by crop varieties and
growing situation. Generally, most essent’al in large amounts are carbon,
hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, magnesium
and iron. In addition, traces of boron, manganese, copper, zine and molybdenum
are also required.

Carbon, hydrogen and oxygen are the main elements of plant bodies. Through
roots or leaves, a crop absorbs oxygen and carbon dioxide from the air and
moisture from the soil. Aided by sunlight, a crop photosynthesizes carbon
dioxide and water to form carbohydrates. So these elements are not needed to.
be added by man.

-~1l-



chin per mou. High figures can be used for paddy rice, cotton and vegetables
and low figures, for wheat and sweet potato. Even lower figures can be
used for beans.

In the growing period, generally the most nitrogen fertilizer should be
applied during the vigorous growth, such as sprouting to the tassel-growing
period for paddy rice, incubation period of unopened flower buds to the
flowering period for cotton, and the period following transplanting, for
tobacco. Nitrogen requirements in the later growth period of crops is much
less. If nevertheless nitrogen fertilizer is applied withovt any nitrogen
deficiency in the later growth period, the crop ripening period will be
delayed, resulting in excessive growth of stems and leaves. Thus, generally
nitrogen fertilizer is most economical and effective as a follow-up fertilizer
in the period of vigorous crop growth.

The fertilizing effect of nitrogen fertilizer is quite obvious. One chin of
nitrogen (about equal to less than 5 chin of ammonium sulfate) can increase
the output of paddy rice by 20-25 chin, wheat by 10-15 chin, about 10 chin
of unginned cotton, 20-30 chin of corn and about 5 chin of rape seeds. When
applied to vegetables, one chin of nitrogen can increase Chinese cabbage
output by 200-270 chin, spinach by 150 chin, and 40-60 chin for potato, sweet
potato and sugar beet.

Main Varieties of Nitrogen Fertilizer

1. Ammonium sulfate: it is a white, fine crystal. Because of impurities,
sometime it is gray, yellow, or pink. Its shape is like granulated sugar.
Many peasants in China call it field-fertilizing powder. This is a chemical
fertilizer applied comparatively early in time in China's rural areas.

Ammonium sulfate contains 20-21 percent nitrogen. In other words, 100 chin
of ammonium sulfate contains 20-21 chin nitrogen. Technical ammonium sulfate
has an acid reaction because it generally contains free acid. It will
increase soil acidity if applied over a long time. Since ammonium sulfate is
a@ physiological acidic chemical fertilizer, the soil can crust over with
excessive application. Why does soil crust over? This is because of
increased acidity in soil and deficiency of organic matter. Thus, elements
in soil such as potassium, sodium and calcium will be quickly leached by
water. Therefore, the granular structure of the soil is destroyed; the soil
becomes crusted. Ammonium sulfate is easily dissolved in water and it can
be quickly decomposed in soil and be absorbed by crops. If ammonium sulfate
is applied with the coordination of barnyard manure, compost and green manure,
organic matter in the soil can be increased and likewise, the essential
nutrients of the crop. Thus, the fertilizing effect is better.

There are generally two ways of making ammonium sulfate. One way is the
direct reaction of synthetic ammonia and sulfuric acid; this is called the
synthetic method because the source of amnonia comes from synthetic process.
Another method is using sulfuric acid to absorb ammonia in coke oven gas
during coking; this is generally called the recovery method of by-product

-Um-



6. Chemical fertilizers can be applied broadly. After applying some chemical
fertilizers, not only nutrients can be provided the crops but the fertilizer
also kills bugs and protects against diseases. For example, once aqua
ammonia or ammonium bicarbonate is applied in a fteld, mole crickets and mites
will be eliminated. Calcium cyanamide protects against schistosomiasis.

Urea can be added to the feeds of ruminants such as oxen and sheep. Precipi-
tated tribasic calcium phosphate is another feed additive of domestic

animals and fowls. Calcium cyanamide is a defoliant for cotton plants.

However, chemical fertilizers also have disadvantages, compared to farmyard
manure. First, farmyard manure contains a bigger variety of nutrients,
especially organic matter and plant growth hormones. Farmyard manure mixed
into soil can bulk up humus content and loosen the soil for granulation,
bettering soil structure. Thus, in the entire crop growth period, essential
nutrients can be uniformly supplied. Chemical fertilizers lack these
features. Generally, chemical fertilizers do not have organic matter but
only simple constituents. For example, ammonium sulfate has only nitrogen;
calcium superphosphate, only phosphorus; potassium sulfate, potassium; and
Ca-Mg-phosphate, only phosphorus, calcium and magnesium but no nitrogen and
potassium. Although some composite and mixed fertilizers contain nitrogen-
phosphorus, nitrogen-potassium or nitrogen-phosphorus-potassium constituents,
these fertilizers still lack the variety of nutrients like farmyard manure
does. Next, some chemical fertilizers favor certain crop and soil. In
other words, not every chemical fertilizer is adaptable to all crops and soils
for increased yields. For example, ammonium chloride cannot be applied to
chlorine-avoiding crops, such as tobacco, sugar cane and sugar beet. Calciun
cyanamide cannot be applied to alkaline soils.

So ‘when chemical fertilizer manufacture is developed, farmyard manure should
be collected at the same time with constant improvement in use technique.
Today China's chemical fertilizer output is very low, not enough to meet the
demands, so farmyard manure is a vital source of fertilizer. One must admit
that farmyard manure is the foundation and chemical fertilizer, the supple-
ment. Even in the future when chemical fertilizer output goes up, farmyard
manure should still be spread on soil. In other words, farmyard manure and
chemical fertilizer are both required. Both have pros and cons; they make
up for each other's drawbacks.

Section 3. Classifying Chemical Fertilizers

Most chemical fertilizers are inorganic compounds, so they are also called

Footnote*: Soil granulation means that the soil forms granular structure
with particle diameters of 1 to 10 mm. After soil granulation, the soil can
hold water and is well permeable by water and air; this favors burgeoning of
the plant's. root system.



4, Ammonium chloride: the industrial form of ammonium chloride is the
halogenide, white or light yellow granulated crystals like table salt.

The fertilizer is hygroscopic but it does not cake easily. It can be
completely dissolved in water with a weak acid reaction. The fertilizer

is fairly stable at ordinary temperatures. At 1LOO°C, it can easily dissolve
to form hydrogen chloride gas. The nitrogen content of ammonium chloride
is 24-25 percent, slightly higher than for ammonium sulfate but not as high
as ammonium nitrate.

In industrial production, ammonium chloride is made in the soda ash industry.
First ammonia gas is passed into a saturated solution of table salt, then
carbon dioxide is let in to yield sodium bicarbonate. Next, the right
amount of table salt is added to precipitate ammonium chloride. The water
then can be removed, to obtain ammonium chloride crystals as the end product.
Since ammonium chloride is produced together with soda ash, rational utiliza
tion of resources should be done to get low costs. Therefore, ammonium
chloride is a fertilizer deserving of broader use.

In experiments and practice, domestically and abroad, ammonium chloride was
shown to have significant effect in boosting crop yields. Especially is the -
fertilizer well suited for calcareous and neutral soils. The fertilizer

has a good fertilizing power for paddy rice, wheat, cotton, rape and ramie.
However, ammonium chloride contains chlorine, besides nitrogen. Chlorine

can easily absorb water, increasing the water content in the crop. Therefore,
when the fertilizer is applied to sugar crops, such as sugar cane, sugar beet
and orange, their sweetness will be reduced. When applied to starch crops,
such as potato.and sweet potato, the starch content will be also reduced.

When applied to tobacco plant, cigarette flavor
will suffer and can cause burning to stop in
smoking from time to time.

Basically, ammonium chloride is used the same way as ammonium sulfate,
either as follow-up fertilizer or basic fertilizer but not as seed dressing.
The fertilizer can be applied either dry or wet, 15-40 chin per mou. When
ammonium chloride is applied to grain crops, the percentage of flour. yield
is 10-15 chin higher per 100 chin than for ammonium sulfate. When ammonium
chloride is applied to cotton or hemp crops, fiber tension can be increased.

Here are precautions when applying ammonium chloride:

(1) Ammonium chloride has selectivity toward crops so the fertilizer should
not be applied to chlorine-avoiding crops, such as sugar cane, sugar beet,
potato, tobacco and tea leaves.

(2) Ammonium chloride is a physiological acid fertilizer. Like ammonium
sulfate, if the fertilizer is applied to acid soil, it should be coordinated
with lime or farmyard manure. However, these should not be mixed, in order
to retain the fertilizing power.

- 20 -



JPRS 71813

6 September 1978

CHINA

ESSENTIALS OF CHEMICAL FERTILIZER USE IN PRC

DISTRIBUTION STATEMENT A
Approved forPublicRelease Reproduced From
Distribution Unlimited Best Available Copy

20000412 131

U. §. JOINT PUBLICATIONS RESEARCH SERVICE



thermal decomposition, maceration, screening and evaporation, potassium

sulfate is obtained. Also obtained is aluminum oxide, a raw material to be
refined into metallic aluminum. Therefore using alum stone to make potas-
sium sulfate is an approach to the comprehensive utilization of resources.

Potassium sulfate does not have a chlorine radical, so it can be applied to
chlorine-avoiding crops. However, potassium sulfate contains a sulfate
radical, a physiological acid fertilizer, like ammonium sulfate in nitrogen
fertilizer. A crop absorbs potassium in potassium sulfate and the sulfate
radical remains in the soil. As a consequence, prolonged use of potassium
sulfate cakes soil. So this fertilizer should be alternated with lime.

Potassium sulfate can be a basic or a follow-up fertilizer, but better as

a basic fertilizer. Generally, 8-15 chin potassium sulfate can be applied
per mou, but use can be as high as 15-30 chin for tuber roots or tuber stem
erops. If pearl ash is applied at the same time, potassium sulfate can

be properly reduced in amount. Application in lowland fields should avoid
too much irrigation water and drainage should be halted afterwards to prevent
loss of fertilizing power. The fertilizer can be applied dry or wet. Dry,
four to five times of moistened soil can be mixed. Wet, the concentration
of potassium sulfate should be kept at about 5 percent, that is, mixing 95
chin water with 5 chin potassium sulfate.

Here are precautions for applying potassium sulfate:

(1) Potassium sulfate should not be applied near crop roots or on stems and
leaves to prevent chemical burns tc the plant.

(2) Potassium sulfate is a physiological acid fertilizer, so it is best
applied to alkaline or neutral soils. If acid soils, lime should be applied i

alternately.

(3) Potassium sulfate is readily soluble in water, so the nutrient is liable
to dissipate in running water. When the fertilizer is applied to sandy soils
it is best applied several times, or else mixed with farmyard manure before

application.

The yield-gain effect in applying potassium sulfate is like that with potassium '
chloride but the amounts should be slightly more.

3. Potassium carbonate (pearl ash): peasants usually burn straw or firewood
as fuel; the remaining ash is called pearl ash. The ash contains potassium
carbonate and considerable impurities. The potassium nutrient amount is
small, generally about 5 percent. This potassium fertilizer does not require
manufacture and have extensive sources of supply. So pearl ash has long been
used as a fertilizer. Industrially produced potassium carbonate has not

yet been applied as a fertilizer.

Pearl ash differs from potassium sulfate or potassium chloride since the ash
is an alkaline fertilizer. We often see that in rural villages clothes are

- 43 -


form, but certain containers and sprayers are required for packaging,
transportation, storage and field use.

Section 4. History of Chemical Fertilizer Manufacturing

Chemical fertilizers are vital in increasing agricultural production so the
industry of chemical fertilizers is an important sector in the national
economy. The world history of chemical fertilizer production is not a long
one. About more than a century ago, experiments and studies were made on
chemical methods in fertilizer manufacture to increase crop unit yield and
fertilizer sources. In 1842, the world's first factory appeared for

making superphosphate by sulfuric acid treatment of bone meal. Later, since
the amounts of bone meal could not meet the demand, it was found that
phosphate rock can replace bone meal for making superphosphate. By 1870,
large bodies of soluble potassium salt were discovered and the large-scale
potassium fertilizer industry thus began. In 1913, the first synthetic
ammonia factory for making various nitrogen fertilizers was built. Later,
nitrogen, phosphorus and potassium fertilizers were made industrially.

With better fertilizer application, chemical fertilizers showed rising ,
benefits on crop yield gains in agricultural production. So the production
and use of chemical fertilizer climbed rapidly. In 1900, chemical fertilizer
use was only 8.3 million tons but the use in 1962 was 120 million tons.

Over a little more than 60 years, chemical fertilizer use grew by 13 times:

a 28,2 times gain for nitrogen fertilizer, 6.82 times for phosphorus ferti-
lizer and 32.8 times for potassium fertilizer. Chemical fertilizer production
also went up by leaps and bounds. Annual synthetic ammonia output in

making nitrogen fertilizer went from 5 million tons in 1950 to 13.3 million
tons in 1962, with the number of plants rising from about 130 to 400 for a
more-than-double increase. The kinds and production and application techniques
of chemical fertilizer were also much developed.

Like other pre-Liberation industries, China's chemical fertilizer industry
was quite backward: only two ammonium sulfate plants made small amounts of
nitrogen fertilizer. No potassium and phosphorus fertilizers were made
either. Under the Party's leadership after the Liberation, the chemical
fertilizer industry grew rapidly, with large gains in its output. All the
main types of nitrogen fertilizers began to be industrially produced and the
phosphorus and potassium fertilizers also began production, starting from
nothing before the Liberation. However, China is a big country with wide
variety of soils and crops, so the demand for chemical fertilizer is
naturally quite high. Today's production is still far below the swelling
demands of its developing agriculture. Based on China's present farm
acreage with a mean annual demand of 30 chin of chemical fertilizer per mou,
annual requirements for chemical fertilizer should be as much as tens of
millions of tons. The increased output of chemical fertilizer directly
promotes greater agricultural production. This is a necessary material
condition for agricultural modernization and to consolidate the collective
economy of people's communes. This necessity shows that the vigorous
growth of chemical fertilizer industry is a difficult but glorious mission.

-7T-



phosphate rock. Such fertilizers are best when mixed with farmyard manure
or spread right on acid soil.

Classifying by Acid and Alkali Characteristics

By using chemical analysis the acidity or alkalinity of soils and fertilizers
can be determined. This is how to decide what fertilizer is best for a
particular soil type. By acidity and alkalinity, chemical fertilizers can
be divided into acid, alkaline and neutral fertilizers.

1. Acid chemical fertilizers can be subdivided into two types: one type
exhibits chemical acidity with its water solution showing an acid reaction,
such as ammonium sulfate and calcium superphosphate. Another type exhibits
physiological acidity with its water solution showing a neutral reaction,
However, after a physiological acid fertilizer is applied to soil; part of
the nutrients is absorbed by the crop. The rest in the soil is acidic.
These fertilizers are ammonium chloride, ammonium sulfate and potassium
sulfate.

2. Alkaline chemical fertilizers can also be subdivided into two types: one
type exhibits chemical alkalinity with its water solution showing an
alkaline reaction. One of these fertilizers is calcium cyanamide. Another
type exhibits physiological alkalinity with its water solution showing an
alkaline reaction. After these fertilizers are applied to soil, part of the
nutrients is absorbed by the crop. The rest in the soil is alkaline. One
such fertilizer is sodium nitrate.

3. Neutral chemical fertilizers do not show acid or alkaline reactions
either before or after application to soil. Any soil can be treated with
these fertilizers without affecting soil characteristics even after long use.
One such fertilizer is urea.

Classifying Nutrients in Fertilizers

1. A single-element chemical fertilizer only contains one nutrient, such as
ammonium sulfate (nitrogen), calcium superphosphate (phosphorus) and potassium
sulfate (potassium).

2. Multi-element chemical fertilizers contain two or more nutrients, such as
ammonium phosphate containing nitrogen and phosphorus.

Classifying by Fertilizer Forms

1. A solid fertilizer is a fertilizer made into crystalline, granular or
powdered form in a factory; thus, it is convenient in packing, transportation
and application. Except for liquefied ammonia and aqua ammonia, all nitrogen,
phosphorus and potassium fertilizers are prepared as solids.

2. A liquid fertilizer is a fertilizer. made as a liquid, such as liquef ‘ed
ammonia and aqua ammonia. Production cost is lower than that of the solid

-6-



if an iron drum has to be used, its ianer side should be coated with
unboiled varnish, red. lead, asphalt or other corrosionproof paints.
Wooden drums cannot long withstand corrosion by aqua ammonia, so corrosion-
proof paints should be applied to the inner suiface. Earthenware jugs are
corrosionproof, so they can be used as containers for aqua ammonia. Leakage
should be checked by pouring in water. ~

Section 5 Toxicity Prevention

Calcium cyanamide is a toxic fertilizer, so paper bags or iron drums con-
taining the fertilizer should be protected from accidental tearing during
transportation or storage. The operator should wear a mouth mask and
gloves during packaging and transportation. Afterwards, the hands should
be washed, especially before meals.

~ 56 -



In manufacturing, first the phosphate rock is sintered with small amounts
of silica or Glauber's salt and phosphoric acid (or low melting-point
phosphate rock is used) at high temperatures. Then water vapor is admitted
to remove fluorine in the phosphate rock and the mixture is mixed with
water for sudden cooling. The end product of defluorinated phosphate is
obtained after drying and grinding. Why does fluorine have to be removed?
Because fluorine is not a crop nutrient and too high a content is harmful.
The finer the ground defluorinated phosphate, the better the fertilizing
power. Fertilizer containing less than 0.1 percent of fluorine can be
used as supplementary feed for cattle.

The fertilizing power of defluorinated ‘phosphate is like that of Ca-Mg-
phosphate, but it is lower than for calcium superphosphate. However, if
defluorinated phosphate is applied in acid soils, the fertilizing power is
not less than calcium superphosphate. The fertilizer is generally used as
basic fertilizer in the amount of about 15-40 chin per mou.

7. Pulverized phosphate rock: it is made by grinding monite rocks. Pulver-
ized phosphate rock is brown in the form of dry soil passing through a fine
sieve.

What is monite? The answer lies in the classification of phosphate rocks.
Natural phosphate rocks can be classed into two types:

(1) Apatite: this is a rock formed by condensed magma ejected through a gap
in earth's crust. Geologically, this is called igneous rock in the form of
light green or gray crystals. The main content is calcium fluophosphate
or calcium chlorophosphate. The phosphorus pentoxide content is usually
less than 15 percent; the level of impurities is high. This is a slightly
soluble phosphorus fertilizer.

(2) Monite: it is in the form of fragmented or powdered rock; geologically,
it is called sedimentary rock since it was deposited through hydraulic
sedimentation onto the water bottom. Monite is light gray or brown in

the form of amorphous powder. The main contents are the same as that of
apatite but the phosphorus pentoxide content is higher, usually over 15
percent and as high as 38 percent. One part of the phosphorus content was
decomposed by organic acid secreted by plants, so the phosphorus content
is easily absorbed by plants and the impurity content is low.

The pulverized phosphate rock is suitably applied to acid soils, but not

to neutral or alkaline soils. The powder can be used as a basic fertilizer,
but not as a follow-up or seed fertilizer. The fertilizing power is high
if the powder is mixed and piled with farmyard manure before its applica-
tion. Usually, 100 chin barnyard manure, 4 chin pulverized phosphate rock
and 5 chin slaked lime are mixed, piled and macerated. One week before
sowing, the mixture is ditch applied and a thin layer of soil is covered
over theappplication sites before sowing. Or, the powder can be uniformly
spread to the soil before deep plowing. The fertilizing effect is quite

- 39 -



key of Figure 2 on preceding page/

1. Aqua ammonia 9. Cooling

2. Liquefied ammonia 10. Applying pressure
3. Ammonium sulfate lL. Sulfuric acid

4. -Ammonium chloride 12. Table salt,

5. Ammonium nitrate Carbon dioxide

6. Urea 13. Nitric acid

7. Ammonium bicarbonate 14. (Applying pressure)
8. Water 15. Carbon dioxide

8. Ammonium calcium nitrate: it is also called as lime ammonium nitrate.
Ammonium caleium nitrate is made by first melting ammonium nitrate to which
the right amount of limestone or dolomite powder has been added. Since
ammonium nitrate is an acid fertilizer and is explosive and easily caking
under certain conditions, it is further processed into ammonium calcium
nitrate fertilizer to improve its characteristics.

Ammonium calcium nitrate consists of grayish white or grayish brown parti-
eles; the color differences come from the different origins of the raw
materials added. The fertilizer is hygroscopic but not likely to cake. ’
It can be dissolved in weakly alkaline water, with about 20 percent nitrogen.
Owing to different combining ratios in manufacturing, nutrient content varies.
This fertilizer is well adaptable to acid soils found in Hunan, Hupeh,
Kiangsi, Chekiang and Fukien provinces. It can be widely accepted in these
areas.

Ammonium calcium nitrate is applied just like ammonium sulfate and ammonium
nitrate. The fertilizer can be used as basic fertilizer or as a follow-up
fertilizer. Dry, fine soil can be mixed withthe fertilizer for ditch or
hill application. Alternatively, 30-50 times of water can be mixed for
spraying applications. Soil moisture should be properly maintained after
application by covering with soil. Thus, a certain water content can be
kept to sufficiently dissolve the fertilizer in order to exploit its full
fertilizing effect. Ammonium calcium nitrate is best combined with soil
loosening and weeding, such as during the return-to-green period of winter
wheat. Here first one digs ditches between two adjacent planting rows to
apply the ammonium calcium nitrate. Then one loosens the soil and covers
the ditches with soil to have a good fertilizing effect.

The amount of ammonium calcium nitrate applied should be generally 10 per-
cent more than for ammonium nitrate.

Ammonium calcium nitrate cannot be mixed with calcium superphosphate, to
avoid undercutting the calcium superphosphate fertilizing effect.

The ammonium calcium nitrate increases corn yield by 50 percent, paddy rice,

by 21 percent, wheat, by 20 percent and cotton by 17 percent, if 15-45 chin
of fertilizer is applied per mou.

- 27 -



laundered with the soaking water of pearl ash. This is because the ash con-
tains alkali, which can remove dirt.

Pearl ash can be epplied to most soils and especially, to laterite in South
China. However, the ash is unsuitable in saline and alkaline soils. Pearl
ash can be applied to all crops and best of all to chlorine-avoiding crops,
such as tobacco, sugar cane, sugar beet and potato. If the ash is applied
for a long time, the soil will not crust over as in the case of potassium
sulfate. Pearl ash can be used as a basic or a follow-up fertilizer.
Generally, the amount of the ash applied is 50-100 chin per mou and even more
for crops requiring more potassium, such as sugar beet and potato. The ferti-
lizing effect of 5-10 chin pearl ash equals 1 chin potassium sulfate.

Here are precautions for applying pearl ash:

(1) The pearl ash should not be mixed with ammonium sulfate or ammonium
bicarbonate, since this mixing will cause nitrogen loss. In addition, ash
should not be mixed with calcium superphosphate: mixing will impair crop
ability in absorbing phosphorus nutrients.

(2) Potassium nutrient in the pearl ash is readily soluble in water, therefore
the ash should not be wetted by rain to avoid loss of the fertilizing power.

Besides these potassium fertilizers, potassium-calcium composite fertilizer
can be made through improvized methods, with orthoclase and limestone as
raw materials and by mixing them and calcination to meet local demands.

Section 4. Composite Fertilizers and Mixed Fertilizers

The above-mentioned nitrogen fertilizers, phosphorus fertilizers, or potas-
sium fertilizers contain only one nutrient. The composite fertilizer and
mixed fertilizer contain more than two nutrients, so they are called multi-
effect fertilizers. The composite fertilizer is usually made through chemical
reactions and mixed fertilizer is made through mechanical means.

Here are the advantages of composite fertilizer and mixed fertilizer:

(1) A crop plant can obtain more than two kinds of nutrients through one
fertilizer application.

(2) The undesirable characteristics of chemical fertilizer can be improved
and disadvantages of some fertilizers in soil can be avoided.

(3) Since a type of fertilizer contains more than two nutrients, transporta-
tion and application labor can be reduced.

Therefore, composite fertilizer and mixed fertilizer have a good future.
At present, there are up to a thousand brands of composite fertilizer and

mixed fertilizer in the world. Here are the common types:

- 4h



should not touch aqua ammonia during application, otherwise the skin will
be burned or injured. :

From experience in applying aqua ammonia in China, the yield-gain effect of
3 chin aqua ammonia (containing 20 percent nitrogen) equals that of 2.5 chin
of ammonium sulfate. In aqua ammonia, each chin of nitrogen (equivalent to
6-7 chin of aqua ammonia, containing 20 percent nitrogen) can boost the
paddy rice yield by 20-25 chin, wheat yield, about 15 chin, corn yield,
25-35 chin, unginned cotton yield, about 10 chin, rape seed yield, 6-8 chin,
Chinese cabbage yield, about 60 chin and sugar beet yield, about 140 chin.

7. Liquefied ammonia: cooled ammonia gas and condensed under pressure ends
up as liquefied ammonia; this may be directly applied as a fertilizer.
Liquefied ammonia is a colorless liquid containing 82 percent nitrogen.
Although its nitrogen content is high, it is very volatile at room ‘tempera-
ture. If liquefied ammonia is not enclcsed in a special container, all cf
it will escape as gas. In production, the container for liquefied ammonia
is a steel storage tank capable of withstanding a pressure of 16-17 atm.
When the fertilizer is delivered, it is packed into a specially-made steel
bottle, which can also withstand a pressure of 16-17 atm. During applica-
tion, machinery under compression should also be used and ejectors to eject
liquefied ammonia into the soil. Since applying it is fairly complicated,
liquefied ammonia is limited in its acceptance. The concentration of
liquefied ammonia is high and so is its pressure. Therefore, application
machinery should be required to eject the fertilizer deep into soil,
followed by covering with more soil. Usually, 3-8 chin of liquefied ammonia
is enough for each mou of farm field. The seven nitrogen chemical ferti-
lizers discribed about are made with ammonia as raw material. To help
readers to remember these fertilizers, Figure 2 shows a graphical illustra-

tion as follows:
Ca):
1

Figure 2. Witrogen Fertilizers Made With
Synthetic Ammonia
[Key on following page/

- 26-



[fable continued from preceding page/

Fertilizer Nutrient content Fertilizer Nutrient content
type nitrogen phosphorus potas- type nitrogen phosphorus potas-
4 pentoxide sium % pentoxide sium
oxide % t oxide %
ammonium 20 potassiun 48~52
calcium sulfate
nitrate
ammonium 12718 45~52
sodium 15 phosphate
nitrate
potassium 1 4s
calcium 18 ~20 nitrate
cyanamide
ammonium 23 16~18
calciun 16~18 calcium
superphos- superphos-
phate phate
concentrated more
superphos- than 45
phate (46 is
used in
calcula-
tions of
examples)

How to make conversion calculations? For example, 30 chin of ammonium
nitrate was applied per mou as the fertilizing norm. If urea is applied
instead, how many chin should be used? We should calculate by the follow-
ing formula:
nitrogen content in ammonium sulfate
30 chin x = required amount for urea.
nitrogen content in urea

From this table, the nitrogen content in ammonium sulfate is 20.8 percent
and that of urea, 40 percent; then these figures are substituted into the
above formula:

30 chin x 18/46 =7.8 chin.
That is, 7.8 chin of calcium superphosphate should be applied.

This calculation method requires a separate computation each time. To
simplify, the following table can be used to directly read out the figure
representing the converted amount to be used. However, only integers are
used for the nutrient content, so the decimal remainder may differ in the
table figure and the calculated figure.

- 63 -



Sources of the above-mentioned farmyard manure are very wide; they contain
many nutrients. However, nutrient amounts are quite low. So these farmyard
manures cannot supply large farm fields. In addition, much labor is required
to accumulate farmyard manure. Through research, coal, coke, natural gas,
petroleum air and minerals can be used as raw materials to manufacture,
through chemical processing, fertilizers containing nitrogen, phosphorus and
potassium and other elements. Chemical fertilizers is the subject of this
book.

Section 2. Advantages and Disadvantages of Chemical Fertilizers
Chemical fertilizers have these advantages:

1. Highly effective nutrients and rapid fertilizing effect: one chin of ammo-
nium sulfate equals 30 to 40 chin of human feces and urine; one chin of
calcium superphosphate equals 60 to 80 chin of barnyard manure; and one chin
of potassium sulfate equals about 10 chin of pearl ash. Especially, some
highly concentrated chemical fertilizer contains even more effective nutrient.
So proper amounts of chemical fertilizer in each mou in addition to farmyard
manure, according to soil and crop situations, can fill crop growth require-
ments. Most chemical fertilizers readily dissolve in water; so their
applications to soil can be quickly absorbed by. crops with fast and apparent
fertilizing effect. Small, yellowing and withering crops can grow vigorously
once nitrogen fertilizer like ammonium sulfate is applied.

2. Abundant raw materials: natural minerals are used as raw materials for
manufacturing chemical fertilizer. Coal, petroleum, rock phosphate are
principal raw materials of chemical fertilizer. China has heavy reserves of
these minerals.

3. Large-scale plant production is feasible. Since the raw materials for
chemical fertilizers are natural minerals and mechanization is used in
manufacture, chemical fertilizer can be made in large plants. Such plant
production is free of seasonal limitations.

4, Labor economies: the nutrient contents of chemical fertilizer is high,

so generally small amount of fertilizer in granules or powder suffices for
the crops. Therefore, labor required for applying chemical fertilizer is

much smaller than for farwyard manure. Likew!se, labor in transportation

can be also properly reduced.

5. Chemical fertilizers can be conveniently stored for long periods. Since
the bulk of chemical fertilizer is smaller than farmyard manure, proper steps
can be taken based on its characteristics so as to store chemical fertilizer
for a long time without deterioration. Large spaces should be set aside for
piling and wiacerating farmyard manure; sometimes, farmland is required for
piling up manure.



reported by the Institute of Soils and Fertilizers of China Academy of Agri-
cultural Sciences, the fertilizing effect of ammonium nitrate for paddy rice
is about 90 percent that for ammonium sulfate, with equivalent nitrogen
content. Experiments in Kiangsi, Kwangsi, Szechwan and Ningsia provinces
reported like results. There were also similar reports in Japan. Ammonium
nitrate dissolves easily in water, with high hygroscopicity. Caking follow
if improper storage leads to moisture coatact. It is best to dissolve
caked material in water, or lightly crush it with a wooden hammer. No iron
hammer can be used in crushing because ammonium nitrate may then explode |
violently. Do not fear its explosion characteristics. When ammonium
nitrate is not near flame and not violently shocked, it does not explode at
ordinary temperatures.

Ammonium nitrate contains high percentages of nitrogen and is quite adaptable |
to crops and soils, so it is a good chemical fertilizer. In addition, it can |
be also made into dynamite as a trend in ammonium nitrate production.

Ammonium nitrate is made by the reaction of ammonia with nitric acid, which
reacts with ammonia and oxygen in the atmosphere through a catalyst at high
temperatures. Then water is used to absorb the final product. So ammonia ’
is used as the major raw material in making ammonium nitrate. Allow ammonia

gas to pass through a dilute nitric acid solution; it then becomes an ammonium
nitrate solution. The end product of ammonium nitrate forms through the steps
of evaporation, crystallization, separation and drying. To avoid ammonium
nitrate caking on contact with moisture, the fertilizer is made into granules,
to which have been added fillers, such as dolomite, kaolin and diatomite to
avoid caking.

Since ammonium nitrate has concentrated fertilizing power and a rapid effect,
it is best as a follow-up fertilizer. The amount used should be less than
that for ammonium sulfate, generally about 8-30 chin per mou of ammonium
nitrate. When small amounts of this fertilizer is used, six to eight times
fine dry soil can be mixed before a scattering application. Or, 50-70 times
of water is mixed for a spraying application. It is forbidden to spray
during dew, dense fog or drizzle because the fertilizer tends to stick to
stems and leaves of the crop and injure through chemical etching.

These are precautions when applying ammonium nitrate:

(1) Protection from moisture is important because ammonium nitrate is highly
hygroscopic. Explosion may occur at high temperatures or under violent frie
tion, so special precautions should be followed in transportation, storage
and application. Never store ammonium nitrate with flammables like kerosene,
diesel oil and coal. Violent shock should be prevented when moving this
nitrate. Never store ammonium nitrate ina place in high temperatures, as
in direct sun exposure. No explotion will occur if flame, high temperatures

or violent shock are avoided.

(2) The fertilizing power of ammonium nitrate is quite concentrated; its
appearance is very similar to ammonium sulfate so care should be taken to

-17-



Chapter 4. Packaging, Transportation and Storage of Chemical Fertilizers

Chemical fertilizers are industrial products, so’ the output is high because
continuous production is feasible. Frequently, chemical fertilizer produced
in a plant can meet the demands of several communes or even several counties.
However, agricultural demand is seasonal. Therefore, packaging, transporta~
tion and storage are required. Since there are solid or liquid chemical
fertilizers and different types have different characteristics, inappropriate
treatment will lead to loss of fertilizing power, to waste, or even to

mor incidents. Thus, there are problems in packaging, transportation

and storage.

When the characteristics and application methods of various chemical ferti-
lizers are described, some precautions on packaging, transportation and
storage have been enumerated. However, the descriptions are not conducted
systematically. Here are comprehensive descriptions of these problems.

Section 1 Protection Against Moisture and Water

Most chemical fertilizers are hygroscopic. Fertilizers like ammonium nitrate,
ammonium sulfate and potassium chloride cake after absorbing moisture. So
these fertilizers should be broken up before application. Many chemical
fertilizers are soluble in rainwater, like urea, calcium superphosphate and
potassium sulfate. The nutrients will be lost once wetted in a shower,
Chemical fertilizers like ammonium bicarbonate decompose readily after
absorbing moisture.

To protect the fertilizer from moisture and water, gunny bags are used to
pack ammonium sulfate and calcium superphosphate; four to five layers

kraft paper bags with asphalt interlayers are used to pack ammonium nitrate;
plastic bags are used for ammonium bicarbonate; and iron drums, for cal-
cium cyanamide. If the packing bag is broken, the bag should be mended or
discarded.

Dryness is essential during transportation and storage. The bag should not be
placed in mist place and protection should be provided against wetting by
rain. , A cover should be provided during transportation and waterproofing
should be maintained during the rainy season. _ When wooden ‘boats transport
the fertilizer, overloading is strictly forbidden and waterproofing is vital.

- Ok -



{fable continued from preceding page/

Type of
chemical Appearance Solubility
fertilizer

precipi- insoluble
tated
phosphate

defluori- insoluble
nated
phosphate

pulverized brown pow-
phosphate der

rock

potassiun completely
chloride soluble
potassium completely
sulfate soluble
ammonium completely
phosphate soluble
potassium completely
nitrate soluble

Mixing with

lime Heating, com-~

without ammo-
nia odor

without ammo-
nia odor

ammonia odor
without

ammonia
odor

- 61 -

bustion

glowing and
smoking but
without ammo-
nia odor

External
observation
after other
processes

white or
light yellow
powder

white, gray-
ish black
particles
or powder

white
powder

white tiny
erystalline
particles



available phosphorus, less than 4.5 percent. free acid*, and water content
between 13.5 and 15 percent. Grade B product contains 16-18 percent available
phosphorus and grade C contains 14-16 percent available phosphorus. In
China, the end products are either grade A or grade B; there is no grade C

in China. Calcium superphosphate also contains gypsum and other sulfates,
such as ferric sulfate and aluminum sulfate.

Bone meal was the raw material in the beginning for making calcium super-
phosphate. Then phosphate rock was found to be a substitute for bone meal.
Phosphate rock is first broken to a certain fineness and concentrated
sulfuric acid is added to decompose the broken rock into calcium superphos-
phate. Calcium superphosphate requires large amounts of sulfuric acid; its
output is decisively boosting calcium superphosphate output.

These characteristics of calcium superphosphate should be understood before
applying it. These characteristics are:

First, calcium superphosphate dissolves easily in water and has a fast ferti-
lizing effect. After soil treatments, the available phosphorus nutrient is
dissolved in soil water.

Secondly, though calcium superphosphate is readily soluble, yet some of the
fertilizer is often precipitated by iron and aluminum in the soil to deny
full utilization by a crop. In acid soil, this precipitation is very serious
and even tends to crust soil.

Thirdly, after phosphorus nutrient is precipitated, the nutrient moves
sluggishly and stays at the application sites. If these sites are distant
from the crop roots, the roots cannot absorb this nutrient. If the ferti-
lizer application sites are too close to the sowed seeds, evaporation of
free acid will hamper seed sprouting. So particular attention should be
paid to the depth and distance from the crop plant when applying calcium
superphosphate. Calcium superphosphate is most suitably applied to neutral
and alkaline soils; application is also feasible for acid soils. This
fertilizer can be used as basic, seed and follow-up fertilizer and can
also be mixed with farmyard manure, like barnyard manure and compost.
Application depth is about 3-5 ts'un. When used as seed dressing, calcium
superphosphate can greatly promote the growth of crop radicles, causing
vigorous life in the later period of plant life. Applications to cotton
plants should be lighter. Once the fertilizer adheres to the fine hairs
of a cotton seed, seed sprouting will be hampered. When used as follow-up
fertilizer, ditch and furrow applications should be used; the application
onto the topsoil is not allowed. Depth and distance from the crop plant
should be paid particular attention during application to allow the ferti-
lizer to be easily absorbed by crop roots.

Footnote*: Free acid -- when calcium superphosphate is made using
sulfuric acid for the decomposition of phosphate rock, small quantities
of phosphoric acid are produced and remain in the end product. Too much
free phosphoric acid harms crops, so its content should be limited.

- 3h



Calcium superphosphate can also serve as a follow-up fertilizer outside
roots. Just like urea in nitrogen fertilizer, calcium superphosphate solu-
tion can be sprayed on leaf surfaces. Its concentration is 2 percent; in
other words, 2 chin calcium superphosphate is mixed with 98 chin water.
Stir the solution while mixing and let the solution stand overnight to fully
dissolve the calcium superphosphate, then screen the solution before appli-
eation. The solution should not be placed in an iron drum, so as to avoid
chemical reaction affecting solution quality. Generally, spray this solu-
tion two or three times 7-10 days apart. The advantage of spraying on crop
leaves is avoidance of precipitating calcium superphosphate by soil. How-
ever, this is only one way of fertilizer application and cannot completely
replace application outside crop roots in the soil.

The quantities of calcium superphosphate used are determined by crop
varieties. Generally, 30-50 chin or more of this fertilizer per mou can
be applied to paddy rice. The amounts are smaller for other cereal crops.
As a seed dressing, the amount is 5-10 chin per mou. Here the fertilizer
is mixed with fine, dry soil immediately before application. First the
fertilizer can be applied in a sowing ditch, then a thin layer of soil
covers the application sites before sowing the seeds. Little mud should be
used to mix the seeds of green-manure crop right before sowing.

Here are precautions for applying calcium superphosphate:

(1) Like acidic nitrogen fertilizer, calcium superphosphate should be
ecordinated with lime and farmyard manure in application to keep the soil
from deteriorating. However, it is not allowed to mix lime with calcium
superphosphate.

(2) Calcium superphosphate can increase the cold tolerance of winter wheat,
Therefore, the fertilizer can be applied once before freezing as a follow-up
fertilizer or it is used as the basic fertilizer when sowing winter wheat.
These applications ensure good fertilizing power.

The yield-gain effect of applying 1 chin calcium superphosphate is 1-3 chin
paddy rice, 1-3 chin wheat, about 1-3 chin cotton, 1.5-2.5 chin rape seed or
2-5 chin corn. The yield gain is very pronounced for green-manure crops:
30-100 chin lucerne per chin of calcium superphosphate.

2. Concentrated superphosphate: it contains much more phosphorus nutrient
than does calcium superphosphate. Generally, the available phosphorus
content is 45-52 percent, three times the content in calcium superphosphate.
Gypsum and other impurities are low in content. Because of high available
phosphorus content, the application, transportation and storage can save
labor, expenses and cost. So concentrated superphosphate is more welcome
than calcium superphosphate.

In making concentrated superphosphate, add phosphoric acid into the finely
pulverized phosphate rock to decompose into the end product. Its shape and

-35-



If the trace element compounds are melted with glass powder and after the
precipitation the mixture is ground, the so-called glass fertilizer is
obtained. This kind of fertilizer has many advantages:

First, the trace element content is lowered, so excessive amounts of this
fertilizer are not likely to be applied.

Secondly, the acid secreted by crop roots can slowly dissolve the glass ferti-
lizer for persistent fertilizing effect.

Thirdly, fertilizer can be applied evenly to distribute the trace element
uniformly into the soil.

Fourthly, after trace elements are fused with glass, the mixture exists in
the soil as the silicate, not leachable by rainwater.

Section 6 Other Mineral Fertilizers

Raw materials for these chemical fertilizers are natural minerals, which are
processed chemically into the end products. Some other minerals can be used
by simple treatment; these are the indirect fertilizers. They were long
used widely in China's rural areas. Some of these fertilizers furnish
certain nutrients and some improve the crop growth environment. There are
many varieties with local materials and traditional usage. Here are common
varieties:

1. Lime: lime is widely applied in rural areas of South China. Its main
function is to improve soil characteristics to provide advantageous crop
growing conditions. Therefore lime is regarded as an indirect fertilizer.
Here are some functions served by lime:

(1) Lime can adjust soil acidity or alkalinity. In acid soils, especially
after physiological acid chemical fertilizer. is:;applied, soil acidity is
too high, hampering the growth of crop roots. Lime is alkaline and its
application to the soil can neutralize or reduce acidity.

(2) Lime can promote microbial activity in soil as the lime adjusts soil
acidity or alkalinity and loosens the soil into lumps, providing microbes
with a good environment. Thus, some soil nutrients not absorbable by a
crop can be converted into absorbable nutrients.

(3) In addition to neutralizing soil acidity, lime can eliminate insects
and weeds. There are three types of lime used as fertilizer: quicklime,
slaked lime and limestone.

Quicklime is called calcium oxide chemically and is made by heating lime-
stone. Quicklime is white or grayish white blocks or powder, highly
hygroscopic. Heat is liberated when water is added to quicklime to obtain
slaked lime.

- 50 -



(2) applied to crops after grafting, frost freezing or wind damage for
urgent requirements of large amount of nitrogen fertilizer;

(3) applied to crops whose roots are injured due to pests, flood or drought,
lowering the roots' capability of absorbing fertilizer; and

(4) in other special conditions, such as improving tea, tobacco or mulberry
leaves to form extralarge leaves.

Very dilute urea solution is required when applied outside crop roots.
Generally, 1 percent urea solution (1 chin urea per 100 chin urea solution)
is used in grain crops. A more dilute urea solution, 0.3-0.8 percent, can
be used for melons, fruits or vegetables. If the solution is too concen-
trated, crops will. be damaged through chemical etching. When spraying, care
should be taken to only slightly moisten leaf surfaces; the fertilizing
effect is higher when applied on leaf undersides but this operation is more
difficult. Except during the flowering period, leaf surface fertilizer
application can be conducted in all other periods. Night spraying is best
because the solution will dry slowly since the dew is oresent. Or, spraying
is done at dusk, after five o'clock in the afternoon. High noon spraying
is not allowed because of rapid drying to cause chemically etching to. the
crops.

There are many advantages for applying fertilizer outside roots, such as:
the crop absorbs much fertilizer so the amounts applied can be smaller.
The fertilizing effect is timely so this is convenient in controlling crop
growth. The fertilizer can be mixed with insecticide before spraying for
dual purposes. However, application times are longer for outside roots,
thus consuming more labor. Sprayers should be used for outside-root appli-
cation, so this way is not as simple as root application. The fertilizing
effect when applied outside roots cannot replace all root treatment, so
‘this kind of application can be only supplementary.

Since urea has these advantages, world urea production climbed sharply.
Vigorous gains in urea output are also happening in China. This is a type
of nitrogen fertilizer with a great future.

Here are precautions in applying urea:

(1) Since urea's nitrogen content is high and its fertilizing effect is
fairly slow, the amount used should be small. Otherwise, the crop will grow
thin stems, causing damping-off, late ripening, or chemical etching injury.
Also, urea should be applied as early as possible to allow enough time for
decomposition in the soil. Urea should be applied on sunny days so as to
intensify microbial activity in the soil and promote early decomposition

of urea. These stipulations should be strictly followed, based on soil,
climate and crop conditions.

(2) When applying urea dry, care should be taken not to contact seeds, stems,
leaves and roots and thus to avoid injury through chemical etching.

- 23-



[Key of Figure 3 on preceding page/

1. Ammonium sulfate 11. Ca-Mg-phosphate

2. Ammonium chloride 12. Thomas meal (Thomas

3. Aqua ammonia (ammonium phosphate)
bicarbonate) 13. Pulverized phosphate

4, Ammonium nitrate rock

5. Calcium nitrate 14. Ammonium phosphate

6. Ammonium calcium nitrate 15. Potassium sulfate

7. Ammonium sulfonitrate 16. Potassium chloride

8. Urea 17. Human feces and urine

. Calcium cyanamide 18. Compost

10. Concentrated superphos- 19. Pearl ash, lime

phate

Figure 3 shows a method of checking feasibility fertilizer mixing, for
example:

(Example 1): Can ammonium nitrate be mixed with potassium chloride?

Answer: At the bottom of the table in Figure 3, (4) indicates ammonium
nitrate. At the left. of the table, (16) indicates potassium chloride. The
symbol at the intersection is 0, which means mixing is feasible.

(Example 2): Can ammonium phosphate be mixed with calcium cyanamide?

Answer: At the bottom of the table, (9) indicates calcium cyanamide. At
the left, (14) indicates ammonium phosphate. The symbol at the intersection
is x, which means mixing is not feasible.

(Example 3): Can urea be mixed with potassium sulfate?

Answer: At the bottom, (8) indicates urea. At the left, (15) indicates
potassium sulfate. The symbol at the intersection is e, which means mixing
should be made immediately before application.

(Example 4): Can the three fertilizers, ammonium chloride, potassium sulfate
and pearl-ash, be mixed?

~ Answer: At the bottom, (2) indicates ammonium chloride. At the left, (15)
indicates potassium sulfate. The symbol at the intersection of the two is
o. In addition, at the left, (19) indicates pearl ash and the symbol at
intersection between left (19) and bottom (2) is x. Moreover, the symbol at
the intersection between left (19) and bottom (15) is o. These symbols
mean that ammonium chloride can be mixed with potassium sulfate and potas-
sium sulfate can be mixed with pearl ash. However, ammonium chloride cannot
be mixed with pearl ash. Therefore, these three fertilizers cannot be mixed
together. This means that in case of mixing three or more fertilizers, only
two of them cannot be mixed together so all three cannot be mixed. Similarly,
if two of them can be mixed only immediately before application, then all
fertilizers can be mixed only immediately before application... Storage for
some time is not allowed.

-53-



Chapter 6. Calculating Application Amount of Chemical Fertilizers

The application amount of a chemical fertilizer is closely related to its
nutrient content. The nutrient content in a nitrogen fertilizer is calculated
from the nitrogen content; phosphorus pentoxide content. is the basis of
nutrient calculation for phosphorus fertilizer; and potassium oxide content
is the nutrient basis for potassium fertilizer calculation. Since the nutri-
ent content of various chemical fertilizers varies widely, conversion calcula-
tion should be made in applying a new fertilizer. The following table shows
the nutrient content in some chemical fertilizers. :

Fertilizer Nutrient content Fertilizer Nutrient content
type nitrogen phosphorus potas- type nitrogen phosphorus potas-
pentoxide sium % pentoxide siun
oxide % % oxide %
ammonium 20.8 Ca-Mg- 1418
sulfate phosphate
ammonium 34 Thomas 16
nitrate meal
ammonium 1717.5 precipi- 28 ~36
bicarbon- tated
ate phosphate
ammonium ok defluori- 20~35
chloride nated
phosphate
urea 46
pulver ized 20 134
aqua ammo- 12~16 phosphate
nia rock
liquefied 82 potassiua 50
ammonia chloride

[fable continued on following page/

- 6-



CONTENTS (Continued)

Chapter 4. Packaging, Transportation and Storage of Chemical
Fertilizers... teen eeceee

Section 1. Protection Against Moisture and Water....
Section 2. Prevention of Decomposition and Evaporation.
Section 3. Prevention of Fire and Explosion....
Section 4. Corrosion Prevention..
Section 5. Toxicity Prevention...

Chapter 5. Simple Distinguishing Methods of Chemical Fertilizers.
Section 1. Determination From Appearance.....sseeeeceescescece
Section 2. Water Solubility..
Section 3. Mixing With Lime Addition.
Section 4. Heating and Combusion......

Chapter 6. Calculating Application Amount of Chemical Fertilizers



Potassium chloride can be used as a basic fertilizer or as a follow-up ferti-
lizer. The fertilizer may be mixed with farmyard manure when used as a
basic fertilizer. Used as a follow-up fertilizer, potassium chloride can

be mixed with five to six parts dry, fine soil for furrow or spraying
application. Wet application is also feasible by mixing with 30 to 60 parts
water. The amount of potassium chloride applied is 10-25 chin per mou.

When potassium chloride is used as a follow-up fertilizer, the growing
period of a crop should be understood. For wheat plants, the follow-up
application is a week before germination to one week before the tassel-
sprouting period. For paddy rice, two follow-up applications are made in
the period of transplanting and from the return-to-green to the tassel-
sprouting period. The follow-up application in cotton plants can be made
from the period after seedling transplanting to the incubation period of
unopened flower buds. The application to hemp plants is the same as for
cotton plants. For ramie plants, one additional application of potassium
chloride can be conducted after each cutting.

Here are precautions when applying potassium chloride:

(1). The potassium chloride solution should not come into contact with seéds and
tender leaves, to avoid chemical burns.

(2) No potassium chloride should be applied to some chlorine-avoiding crops,
like tobacco, sugar beet and potato.

(3) In sandy soils, potassium chloride should be mixed with farmyard manure
before application to prevent loss of nutrients.

(4) In acid soils, potassium chloride should be coordinated with lime in
application. However, mixing of these two is not allowed.

(5) Potassium chloride is highly hygroscopic and moisture and storage water-
proof measures are in order.

The yield-gain effect of potassium chloride is , from experimental results,
17 percent for corn, 11-17 percent for early or late ripening rice, 21 per-
cent for cotton and about 30 percent for hemp.

2. Potassium sulfate: it is a white, grayish white or brown crystal as a
water-soluble quick-release fertilizer. Potassium sulfate is soluble in
water and is hygroscopic but is not likely to cake. If there is occasional
eaking, light rapping is all that is needed to scatter the fertilizer. Potas-
sium sulfate contains 48-52 percent potassium nutrient.

The raw material of potassium sulfate is potassium chloride or alum stone.
Potassium chloride and sulfuric acid can react to produce potassium sulfate.
However, potassium chloride itself is a fertilizer, so generally this method
is not used except in special situations. Alum stone is a mineral and
contains potassium sulfate, aluminum sulfate and aluminum oxide. Through

-~4o-



long; sometimes it lasts as long as 2 or 3 years. Since the fertilizing
power is slow but persistent, the amount used can be as high as 50-100 chin
per mou, which is one to two or three times the amount of calcium super-
phosphate used.

The finer the pulverized phosphate rock, the easier the fertilizing power

can be exploited. The fertilizing effects of pulverized phosphate rock differ
for different crops: good effect for legumes, radish, buckwheat and rape
seed, but lower effects in gramineae, such as barley, wheat and corn.

Section 3. Potassium Chemical Fertilizer

Potassium is another important element in fertilizers. Potassium is closely
related to the formation of carbohydrates in crops and potassium exists in
almost all organs and tissues of crop plants, especially abundant in young,
tender parts of leaves and stalks. Potassium can promote starch and sugar
accumulating in a crop, whose photosynthesis and respiration are normal
with sufficient supply of potassium nutrient. The crop plant then will grow
large, strong stalks and filled seeds with higher tolerance against cold
and-disease. When there is not enough potassium for grain crops, germina-
tion weakensand the internodal spacing shortens. When there is serious
potassium deficiency, brown spots appear on drooping leaves, and the fruit
ripening periods are not uniform. So potassium nutrient is essential to a
crop.

Potassium is quite widespread in the natural environment. Granite has 4-6
percent votassium. The total potassium in the soil is high and if all the
potassium nutrient were to be absorbed by crops, the supply could last

for many years. However, 98-99 percent of soil potassium cannot be absorbed
by crops. So artificial means are needed to supplement the potassium
absorbable by crops from the soil. Then potassium fertilizer becomes
necessary for better agricultural output.

The fertilizing effect is significant when potassium fertilizer is applied
in potassium-deficient sandy soil, but insignificant in fertile soils. The
fertilizing effect of potassium is good in hemp, tobacco, sweet potato and
potato. From experiments in Chekiang Province on fertilizing effects in

" jute, jute peel can be thickened, the percentage of finished jute fiber
after washing is increased, the stalks become tougher and the ultimate
tension of the jute fiber is increased by 2-5.5 kg. After potassium ferti-
lizer is applied to tobacco plants, the quality is much improved and the
burning characteristics of tobacco leaves are desirable. After potassium
fertilizer is applied to sugar cane or sugar beet, the sugar content can
be raised by 2 percent and their root tuber is not likely to decay. After
potassium fertilizer is applied to cotton plants, yellow-withering
diseases can be prevented. For corn plants, stripe plague can be prevented.

The crop demand of potassium nutrients is greater during the young seedling
period than the ripening period. ._In some crop plants, such as paddy rice

- 40 -



(Example 2) The amount of concentrated superphosphate used is 13 chin per
mou as the fertilizing norm. If now calcium superphosphate is applied, how
many chin should be required?

Referring to the table, the phosphorus nutrient content in concentrated super-
phosphate is 46 percent. In the “amount of fertilizer used" column, locate
the figure 45. Then trace rightward to locate the figure 13.0 (the amount

of concentrated superphosphate used per mou in chin). Trace upward from
13.0, and at the same time trace rightward from 18 (calcium superphosphate
contains 18 percent phosphorus nutrient) and meet at the intersection 33.3.
This means that the amount of calcium superphosphate used should be 33.3
chin.

(Example 3) The amount of effective nitrogen nutrient needed is 6 chin per
mou as the fertilizing norm. How many chin of urea or ammonium nitrate
should be applied?

It is known that urea contains 46 percent nitrogen nutrient and ammonium
nitrate contains 34 percent nitrogen nutrient. From column 6 (apply 6 chin
pure. nitrogen nutrient) of "amount of pure nutrient used", trace downward.
At the same time, trace rightward from 34 in the “amount of fertilizer used"
column and meet at 17.7, the intersection at column 6. This means that
17.7 chin of ammonium nitrate is required. Trace rightward from 46 in the
“amount of fertilizer used" column and extend to colum 6 at 13.0. This
means that 13.0 chin of urea is required. A similar procedure can be
applied for the other values.

(Example 4) The amount of effective potassium nutrient (potassium oxide)
needed is 5 chin per mou as the fertilizing norm. How many chin of, potas-
sium chloride is required?

Referring to the table, it is known that potassium chloride contains 50 per-
cent potassium nutrient. At column 5 (apply 5 chin potassium nutrient) of
"amount of pure nutrient used", trace downward. At the same time, from 50
in the "amount of fertilizer used" column trace rightward and extend to
column 5 at an intersection 10.0. This means that 10 chin potassium
chloride should be applied.

Of course, other factors should also be considered in changing a fertilizer

type, besides the nutrient amount. These examples only show the calculation
procedures for different fertilizers required based on nutrient content.

1ok2k - -
cso: 8111/2476 END

- 65 -



The soil gas components are generally similar to atmospheric constituents:
mostly water vapor and carbon dioxide, besides nitrogen and oxygen. Oxygen
meets the respiratory need of crop roots. After carbon dioxide is dissolved
“in the soil water, it can speed the dissolution of insoluble matter in soil
and the chemical fertilizer fcr better crop absorption and utilization.

Relationship Between Soil Characteristics and Amounts of Chemical Fertilizer
Applied

Clay has high water- and fertilizer-retaining power, so nutrients are not
easily leached. However, the gas permeability of clay is low. Even with a
single application of more easily soluble fast-release fertilizer, the
fertilizing effect is still good. Sandy soil has low water-retaining
eapability, so nutrients are easily leached. When easily-soluble fast-
release fertilizer is applied, small amounts and multiple applications

should be the rule. Irrigation amounts should be controlled to prevent flcod-
ing irrigation from causing nutrients to be leached out.

The applied amounts of chemical fertilizer should also be determined by soil
fertility. Less fertilizer is applied to fertile soil and more, to infertile: -
soil with the balanced use of more farmyard manure.

Relationship Between Chemical Fertilizer and Soil Acidity and Alkalinity

There are acid, alkaline and neutral types of soils and chemical fertilizers.
Generally, pH values indicate acidity and alkalinity. The pH. value of neutral
reaction is 7. Alkalinity is manifested by a pH greater than 7 and acidity

by a pH less than 7. Generally, a crop will keep up good growth in a neutral
environment. Therefore, acid soil.is better applied with alkaline fertilizers,
such as calcium cyanamide or Ca-Mg-phosphate. Thus, the function of fertilizer
ean be sufficiently exploited to neutralize the soil acidity and improve its
characteristics. Alkaline soil is better applied with acidic fertilizers

such as ammonium sulfate and calcium superphosphate. Of course, some acidic
fertilizer can be applied to acid soils and likewise some alkaline fertilizer
ean be applied to alkaline soils, but the outcome is not as high as applying
acidic fertilizer into alkaline soils and vice versa. Moreover, some supple-
mentary measures should be adopted during or after applying fertilizer. For
example, lime application can neutralize soil acidity. Sometimes, some
alkaline fertilizers (such as Ca-Mg-phosphate) can be put on acid soils after
acid fertilizer.

Besides soil characteristics, crop habits, growing period and climate should
also be noted when applying chemical fertilizers. There are different sowing
and ripening periods between grain and cash crops. There are different
climates in North compared to South China. To the same crop may be applied
different fertilizer types, with different amounts and methods. Some crops
ean be given heavy fertilizer one time and other crops can be given light
fertilizer at other times. These steps vary to suit place and season. So
experienced peasants advised that four factors (climate, soil, seedling

and crop) should be mastered in applying chemical fertilizer.

-10-



Section 7 Mixed Application of Fertilizers

There are great advantages for mixed application of fertilizers: first, the
crop can obtain multiple nutrients in proper ratios at the same time.
Secondly, the fertilizer applied can be fully exploited. Thirdly, labor
ean be saved in fertilizer application. Chemical fertilizer can be mixed
with farmyard manure and other chemical fertilizers. However, not all ferti-
lizers can be mixed before application. After some fertilizers are mixed,
some fertilizing effect will be lost. For example, after mixing ammonium
sulfate and calcium cyanamide, ammonium sulfate will decompose and get lost
to the environment. Although some fertilizers can be mixed, the mixture
should still not be stored for long; mixing should come right before appli-
cation, such as aqua ammonia and potassium sulfate. Fertilizer characteris-
tics determine the feasibility of mixing. All nitrogen fertilizers with
ammonium, such as ammonium sulfate, ammonium nitrate or ammonium chloride,
cannot be mixed with alkaline fertilizers, like pearl ash, calcium cyanamide
or lime. This is because by mixing nitrogen fertilizer (such as ammonium
sulfate) with an alkaline material, the ammonium will decompose into
ammonia gas, escaping into the environment and the nitrogen nutrient is then
lost. Likewise, human feces and urine should not. be mixed with lime for
application.

Figure 3 shows a graphic solution for checking which fertilizers can be
mixed .

rer ! © -- mixing is feasible anytime.

ite 2
POKER) a
wien
Mee
Bes
Bese
max 4
BRA ¥
Ries
BA! ow
meee 1
ure I)
Bae oo)
Bae 13)
mCP u
ARK 17

e -- applied immediately after mixing,
no long storage.

x -- mixing is not feasible.

a

xLx

ee
MARBR

Figure 3.

«[x|e@fo|x|o
ofole|alx

ofolo|x|x[xjole

oO
io]

xfelo[xie

x

sem-[x]ofo[o]olelx|x|[xlo]x
Hann[x]olololofelx|xlxio[x

Gaz msmelx| x] xfele[@ [x |x|: @ 1x

Graphic Solution for Mixing Application
of Fertilizers

Eey on following page]

rxnelolx|!@]0]x [0/0] x1 x

EaBrBe| x/O[0]0;0/0|>*

-52-

AERES
Raney

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ba-5 79

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slowly poured into the cup and a pair of chopsticks are used to stir the
solution. The solution condition is then observed.

1. Ammonium sulfate, ammonium nitrate, ammonium chloride, urea, sodium
nitrate, potassium chloride, potassium sulfate, ammonium phosphate and
potassium nitrate can be completely dissolved in water.

2. Ammonium calcium nitrate, common calcium superphosphate and concentrated
superphosphate are partially dissolved and partially precipitated.

3. Ca-Mg-phosphate, precipitated phosphate, Thomas meal, defluorinated
phosphate and pulverized phosphate rock mostly settle out and show little
dissolution.

4, Calcium cyanamide is only slightly soluble in water with gas bubbles.
Its odor resembles carbide.

Section 3 Mixing With Lime Addition

Take a sample to be mixed with lime or other alkaline substance, like caustic
soda. If an ammonia odor is detected, the sample then can be held to be a
nitrogen fertilizer, a composite or mixed fertilizer containing nitrogen.

Section 4 Heating and Combustion

If the determination still cannot be made in these ways, heat or place the
sample in a fire to observe its melting, smoke color and smoke odor. The
sample can be placed over a thin iron sheet heated by a coal or charcoal
stove.

1. If the sample does not melt on the iron sheet after heating and the sample
does not catch fire when placed in contact with redhot charcoal, but an
irritating ammonia odor is released, this sample is ammonium sulfate.

2. If the sample does not melt on hot iron sheet and white smoke is released
when the sample is thrown onto redhot charcoal, this sample is ammonium
chloride.

3. If the sample releases white smoke when it is thrown on redhot charcoal,
but no ammonia odor is detected, this sample is potassium nitrate.

4. If the sample melts quickly and white smoke released once it is thrown
onto redhot charcoal, this sample is ammonium nitrate.

In the above experiments, special attention should be given to see that very

little sample is used because potassium nitrate and ammonium nitrate will
explode over fire.

- 58 -



be absorbed by the crop? This depends on the kind of chemical fertilizer;
other determining conditions are soil characteristics, climate and management
of field work. Generally speaking, these are the situations:

1. Chemical fertilizers such as ammonium sulfate, ammonium nitrate and
ammonium chloride, are easily absorbed and leached because they are easily
dissolved in water, thus providing fast fertilizing effects.

2. Highly volatile chemical fertilizer will evaporate a little before and
after application in the field. However, if the fertilizer application
method is appropriate, the evaporation losses can be greatly reduced. At the
same time, after the fertilizer is applied to soil, it can be quickly
absorbed by the crop. These fertilizers are ammonium bicarbonate and aqua
ammonia.

3. Some phosphorus fertilizers can in part be quickly absorbed by soil. The
rest is easily precipitated by iron and aluminum in soil, so the crop only can
absorb a very small portion or none at all. Calcium superphosphate is such
a fertilizer. Other phosphorus fertilizers are hard to dissolve in water,
with slow decomposition in soil, so the crop does not readily absorb these
fertilizers, but in contrast they do not tend to be leached and have longer
fertilizing effects. Ca-Mg-phosphate is such a phosphorus fertilizer.
Generally speaking, a crop will not absorb all the nutrients of a chemical
fertilizer but only a percentage of it. The utilization rate of the first
harvest is generally 50-65 percent for nitrogen fertilizers, 20-40 percent
for phosphorus. and 50-60 percent for potassium fertilizers. The fractions
not currently utilized may be leached with water; only these ere losses.
So chemical fertilizer should be well preserved and. application techniques
should be mastered for its scientific utilization in reducing losses. Then
its function can be more fully exploited. This is vital.

-12-



JPRS 71813

6 September 1978

ESSENTIALS OF CHEMICAL FERTILIZER
USE IN PRC

Peking SHIH-YUNG HUA-HSUEH FEI-LIAO TI I-PAN CHIH-SHIH in Chinese

Aug 74 pp i-iii and pp 1-72

[Book compiled by Wang Nai-ch'iang [3769 0035 1730], Fuel and

Chemical Industry Publishing Service, Peking, 1974, 216,000 copies,

75 pages]

CoNTENTS

SUMMALY. cece cece cece eee n cere cece ese eeereesseerceseeereresesees

Chapter 1. What Are Chemical Fertilizers?......sseseeseeeeeecececrcncrees
Section 1. Functions of Fertilizer........+- eeeee .
Section 2. Advantages and Disadvantages of Chemical Fertilizers.
Section 3. Classifying Chemical Fertilizers........ seeee .
Section 4. History of Chemical Fertilizer Manufacturing......--+.+++++

Chapter 2. How a Crop Absorbs Chemical Fertilizer. ....cssccesvcccceesveee
Section 1. Relationship Between Soil and Fertilizer.
Section 2. Absorption of Chemical Fertilizer by Crop.....++sseeeeeeees
Section 3. Are All Nutrients in Chemical Fertilizer Absorbed by

A CLEOPR ccecec vce cccecenneeseeeseeseeseeeeneeeresesesrerees

Chapter 3. Characteristics and Methods of Applying Chemical Fertilizers...
Section 1. Nitrogen Chemical Fertilizer......sseseeeessscceceeeceeeeee
Section 2. Phosphorus Chemical Fertilizer.
Section 3. Potassium Chemical Fertilizer.........+.-
Section 4. Composite Fertilizers and Mixed Fertilizers.
Section 5. Trace Element Fertilizers.......sseeeeeeevee
Section 6. Other Mineral Fertilizers... eee
Section 7. Mixed Application of Fertilizers....+sseesceseeeceeceerseers

-a- [III - cc - 80 Sat]
{rr - cc]

PAGE
1

SPORE



field, only a gain of 18 chin of wheat results. This explains why it is
best to increase nitrogen by applying phosphorus.

By characteristics of phosphorus fertilizers, generally there are these three
types:

1. Water-soluble phosphate fertilizer: the available phosphorus, phosphorus
pentoxide, can be dissolved in water and a crop can directly absorb such
nutrient. So the fertilizing effect is fast. Some of the water-soluble
phosphate fertilizers are calcium superphosphate and concentrated superphos-
phate.

2. Citric-acid-soluble phosphate fertilizer: the available phosphorus of
this phosphate fertilizer is insoluble in water, but dissolved in 2 percent
citrie acid or neutral and slightly alkaline solution of ammonium citrate.

So a crop cannot absorb and utilize this fertilizer directly. The ferti-
lizing effect of such phosphate fertilizer is better in acid than in alkaline
soil, although the fertilizing is slow yet persistent. Some of this citric-
acid-soluble phosphate fertilizers are Ca-Mg-phosphate, Thomas phosphate,
defluorinated phosphate and precipitated phosphate.

3. Slightly soluble phosphate fertilizer: this phosphate fertilizer is
insoluble in water and is only slightly dissolved in weak acid. After this
fertilizer is spread in the soil, the fertilizing effect is even slower,
indicating some yield gain as long as one or two years later. After one
application, the fertilizing effect can persist several years. Some '
slightly soluble phosphate fertilizers are pulverized phosphate and bone

meal, which are appropriately applied to soils that are more acidic.

Since the phosphate fertilizers have these characteristics of slow ferti-
lizing effect except for a few types with faster effects, application to
soils does not result in an immediate fertilizing effect. However, this
fertilizer is still important to increase yields through familiarizing with
its characteristics and optimal use.

Common Phosphate Fertilizers

1. Common calcium superphosphate: this is a phosphate fertilizer causing
high gains when used heavily.

Calcium superphosphate is. grayish white or light brown, in powder or particle
form. The fertilizer is hygroscopic and its phosphorus content is soluble
>in water, displaying acid reaction.

Since there are different mineral raw materials in making this fertilizer,

it is differently colored, but generally has the same phosphorus content as
the main nutrient. Grade A calcium superphosphate contains 18 percent

- 33-



(3) Ammonium chloride should not be applied to upland fields with saline soil,
or to fields with poor drainage or irrigation.

(4) Ammonium chloride is better applied several times in small amounts each
or the application should be as early in the season as possible to flush
the chlorine by water into lower soil strata.

(5) If ammonium chloride is wetted by absorbing moisture, it should not be
dried in the sun or over fire because ammonium chloride will decompose into
gas when heated. Fine, dry soil can be used to mix the wet fertilizer, or
it can be mixed with water for spraying application.

Ammonium chloride has about the same strength in yield increase as that of
ammonium sulfate.

5. Urea: human urine contains urea and water. By analysis, generally there
is 1.5-2 percent of urea by weight in human urine since urine contains only
little nitrogen. Because urea is manufactured in chemical method with 45-56
percent of nitrogen, the nutrient content is much increased. Urea is also
called synthetic urea.

Beside use as a fertilizer, urea is an industrial raw material in making
plastics, synthetic fiber, paint and artificial leather. In medicine, urea
can be used as'a drug or as raw material for certain drugs. In addition,
urea can be used in oil refining, ore dressing and.as a developer in
photography. Since these subjects are not part of the book, they are not
described further. Another important agricultural use for urea is feed for
ruminants, such as oxen or sheep.

The raw material in making urea is carbon dioxide. By synthesizing ammonia
and carbon dioxide at high temperature and high pressure, the end product
is urea. In recent years, urea output rose greatly because of these
reasons:

(1) The raw material for urea is carbon dioxide, a by-product of synthetic
urea plants. This is easily obtained compared with ammonium sulfate, which
requires sulfuric acid, or ammonium chloride, which takes table salt.

(2) Urea can be applied to a wide variety of crops and soils and it will not
cause the soil deteriorate even after long use.

(3) Besides fertilizers, urea is also a supplementary feed for ruminants as
well as many important industrial high-tonnage uses.

(4) Urea contains a high level of nitrogen, resulting in low transportation
costs, low labor costs in application, low packaging cost and finally low
production costs.

(5) Urea is stable and is easy to store.

-~21-



NOTE

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mation was summarized or extracted.

Unfamiliar names rendered phonetically or transliterated are
enclosed in parentheses. Words or names preceded by a ques-
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1. Ammonium phosphate: this is a composite fertilizer of light yellow
particles. Ammonium phosphate contains nitrogen and phosphorus elements
and the nutrients are water-soluble as a quick-release fertilizer. The
fertilizer is slightly hygroscopic but it will not deteriorate after
long-term storage.

The raw materials for making ammonium phosphate are phosphoric acid and
ammonia, which is first added to phosphoric acid. Through the tablet-
making and drying processes, the end product of ammonium phosphate is then
obtained as tablets or powder. Since the minerals for making phosphoric
acid are impure, ammonium phosphate also has impurities of ferric phosphate,
aluminum phosphate, magnesium phosphate and fluosilicic acid.

There are different nutrient contents in ammonium phosphate because of dif-
ferent components in phosphate rock and manufacturing methods. Generally
speaking, total nutrient content is 55-70 percent with a 1:2.5-5 ratio

between nitrogen and phosphorus (calculated on a basis of phosphorus pentoxide).
For example, the total nutrient content in monoammonium phosphate is 64 per-
cent, including 12 percent nitrogen and 52.percent phosphorus pentoxide.

The nutrient content of 1 chin ammonium phosphate equals 2 chin calcium super-
phosphate and 0.6 chin ammonium sulfate. Another example: the total nutrient
content of diammonium phosphate is also 64 percent, including 18 percent
nitrogen and 46 percent phosphorus pentoxide.

Ammonium phosphate can be used as basic, follow-up or seed fertilizer. The
amount of the fertilizer used should be determined by soil fertility, crop
variety and cultivation method. Generally, 20-30 chin ammonium phosphate
is applied per mou. The application method is similar to that of calcium
superphosphate and ammonium sulfate.

Here are precautions in applying ammonium phosphate:

(1) Ammonium phosphate is easily soluble in water, so wetting by rain should
be prevented during transportation and storage.

(2) Ammonium phosphate should not be mixed with other alkaline fertilizers,
such as lime, to prevent loss of nitrogen nutrient.

(3) Ammonium phosphate has more phosphorus nutrient than nitrogen nutrient,
so usually nitrogen fertilizer should be added when applying ammonium
phosphate.

The yield-gain effect of ammonium phosphate is higher if applied to nitrogen-
and phosphorus-deficient soils. Usually, ammonium phosphate can mean an
8-20 percent above that of calcium superphosphate besides a steady ferti-
lizing power. With this fertilizer, 30 percent of paddy rice, 18 percent

of wheat, 14-26 percent of cotton or 20-28 percent of sugar beet can be
increased in their respective yields.

- 45 -



Pure calcium cyanamide appears as colorless crystals. However, its
industrial product contains lime, carbon, calcium carbide and other impu-
rities, so it consists of black or grayish black particles. Some calcium
cyanamide is powdery. Its smell is like that of calcium carbide and
slightly dissolved in water. Since calcium cyanamide is highly hygroscopic,
it resembles slaked lime, after absorbing moisture. It will be caked after
prolonged storage. Pure calcium cyanamide is 34.9 percent nitrogen but

the common industrial product has impurities, with only an 18-20 percent
nitrogen content.

Nitrogen: content in calcium cyanamide can be hydrated with soil moisture

and reacts with carbon dioxide in the atmosphere decomposing into cyanamides,
which is then converted into urea, and finally to ammonium carbonate, to be
absorbed by crops. In this conversion, cyanamides are toxic to man, animals
and crops. However, in soils with vigorous microbial activity, cyanamides
can be quickly converted and absorbed by crops. In alkaline or dry soil,

or soil where microbial activity is weak, decomposition of calcium cyanamide
is not complete, possibly halting as the dicyandiamide and persisting in
soil. So calcium cyanamide cannot be applied in the above-mentioned soils
in order not to poison crops.

Beside its nitrogen as a crop nutrient, calcium cyanamide can also eliminate
weeds and pest insects. It can eliminate schistosomes in lowland fields

and eggs of parasitic insects in vegetables. In cotton fields, treating with
calcium cyanamide can defoliate cotton plants early to mature the bolls
sooner, thus boosing cotton yields. When using cotton picking machinery,
leaves should be shed first for convenience in collecting unginned cotton.
Other fertilizers normally lack these side benefits.

Raw materials to make calcium cyanamide are limestone, coke and nitrogen.
First, limestone and coke are fed into an electric furnace and made into
calcium carbide. This is then ground into powder to be fed into a nitrading
furnace*. First, switch on the electric current then admit nitrogen for
nitrading. After cooling, grinding and packaging, the end product is
ready. Calcium cyanamide is made differently from nitrogen fertilizer
made with synthetic ammonia, but high-pressure equipment is not required.
Production equipment is comparatively simple but power consumption is
fairly high. Calcium cyanamide is a chemical fertilizer capable of wider
use in areas that have abundant power, low power cost and availability of
raw material, espicially where there is much hydroelectric power.

Since calcium cyanamide shows a slower fertilizing effect in soil and
becomes toxic during its decomposition, it should be applied 10-15 days
before sowing, when used as basic fertilizer. After application, the
fertilizer should be plowed over deeply and the application should be done
even earlier in the case of sandy soil. If the time when the basic ferti-
lizer is applied is very close to sowing time, cyanamides during decomposi-
tion can often affect the sprouting of seeds or harming the growth of

Footnote*: Nitrading furnace is a unit of equipment for nitrading calcium
carbide with nitrogen.

- 29 -



5. Precipitated phosphate: it is a white or light yellow powder, insoluble
in water. The precipitated phosphate is a citric-acid-soluble phosphorus
fertilizer, not hygroscopic and not caking. In manufacture, hydrochloric
acid, nitric acid or sulfuric acid (or the used acid in some plant) can be
used to treat phosphate rock to first extract phosphoric acid. Then lime
water and pulverized limestone or either of them are added to neutralize
the solution. The end product is obtained after screening, washing, drying
and grinding.

The phosphoric acid used to precipitate calcium phosphate is generally
manufactured with hydrochloric acid because hydrochloric acid is compara-
tively low priced and also it is a by-product after electrolysis of table
salt and processing chlorine*. In addition, hydrochloric acid is made
quite simply. The end product by using nitric acid usually contains ammo-
nium nitrate and precipitated phosphate.

The precipitated phosphate is generally used as basic fertilizers. The
fertilizing effect of the precipitated phosphate is better than calcium
superphosphate andthe fertilizer is not easily precipitated by soil iron
and aluminum. The fertilizer contains much calcium, which can neutralize
some of. the soil acid as it dissolves.. Thus soil acidity is reduced. In
neutral soil, the fertilizing effect of precipitated phosphate is less than
with calcium superphosphate.

The way of applying precipitated phosphate is like that of calcium super-
phosphate, usually 15-35 chin per mou.

Besides fertilizer, pure precipitated phosphate can be used as supplementary
feed for domestic fowls or animals to supplement phosphorus and calcium
nutrients.

The precipitated phosphate should not be mixed with alkaline fertilizers,
such as calcium cyanamide, lime or pearl ash, otherwise the fertilizing
effect will be reduced.

In the fertilizing effect of the precipitated phosphate, in acid soil 1 chin
of this fertilizer is equivalent to 1.5-2 chin calcium superphosphate.

6. Defluorinated phosphate fertilizer: this is grayish white or grayish black
in the form of particles or powder. The fertilizer does not dissolve readily
in water. By different manufacture processes, the fertilizer can be divided
into sintered and fusion defluorinated phosphate fertilizers, containing

usually 20 percent available.phosphorus and sometimes as much as 38 percent.

Footnote*: Table salt is mostly sodium chloride. Dissolve table salt in
water to get a solution, which is then poured into an electrolysis bath.
Switch on the electric current. The table salt solution is electrolyzed
into caustic soda, chlorine and hydrogen. Chlorine and hydrogen are then
led into a chamber to start the combustion reaction to get hydrogen chloride
gas, which is dissolved in water to yield hydrochloric acid.

- 38 -



(3) Urea is hygroscopic (less so than ammonium nitrate but more so than
ammonium sulfate) so it should be placed in dry places.

The yield-gain effect of urea is 10-15 chin of paddy rice, 5-8 chin of wheat,
3-5 chin of cotton and 8-15 chin of corn per chin of urea application.

As stated, urea can be also used as a supplementary cattle feed. Why?
Because nitrogen in urea can be utilized by microbes inside the ruminant
stomachs to convert into protein, which is then digested by the stomaches
and absorbed by the intestine as nutrients. Calculation shows that. each
chin of urea equals more than 2 chin crude protein, 2 chin digestible protein
or 5.5 chin bean cake. After a cow eats feed mixed with urea, the lactating
period can be one month longer, the milk yield -~- 10-20 percent more and
feed expenses -- 10-20 percent less.

Daily urea given as supplementary feed is generally 0.05 percent of animal
body weight. The daily ration should be fed in several sessions. To start,
less than 0.05 percent of body weight should be given. Later, the amount
fed can be gradually increased, based on animal's adaptation. Overfeeding
of urea is not allowed. Urea cannot be used as the only feed because it ,
does not contain carbohydrates and fat, so it cannot replace grain feed.

The amount of urea mixed is generally less than 1 percent of total feed.
Never exceed this value. Urea cannot be dissolved in water as a feed because
this may poison the animal. Generally, urea can be made into cakes or balls
together with other feeds. However, urea shauld not be mixed with uncooked
soybean, bean cake, melon seeds or green grass. At present, there has not
been enough experience in using urea as a supplementary feed. So defore
feeding urea, get consultation and guidance from veterinarians or the appro-
priate technicians.

6. Aqua ammonia: the main component in aqua ammonia is ammonium hydroxide,
colorless or faintly yellow. Aqua ammonia is a volatile liquid with a bad
odor, irritating to the nose. Its volatility increases with temperature.
Aqua ammonia has an alkaline reaction and is corrosive. Its nitrogen content
is determined from its water content. In other words, the more water in
aqua ammonia, the lower the nitrogen. Usually, there is 12-16 percent
nitrogen of agricultural aqua ammonia. Sometimes there may be as little

as 10 percent nitrogen.

Like ammonium nitrate, urea and ammonium bicarbonate, once aqua ammonia is
applied to soil it can be completely absorbed by the crop without any residue.
Thus we see that aqua ammonia adapts readily to soil conditions. Since it

is liquid,aqua ammonia is not as convenient as a solid in transportation.

Aqua ammonia is made fairly simple. Generally, ammonia gas is passed through
water, dissolving to yield aqua ammonia. Or ammonia-containing coke oven
gas during coking absorbs ammonia content in its water forming aqua ammonia.
Sometimes aqua ammonia has been made; carbon dioxide is admitted in to yield
the mixed solution of ammonium carbonate and aqua ammonia in order to lower
its volatility. This kind of ammonia, with carbon dioxide passed into it,

is called carbonated aqua ammonia. Manufacturing it is simple and its

~ 24 =



Small amounts of chemical fertilizer mean high agricultural yield; this is

the most rational and economical task. Therefore, fertilizer application
should be stressed. Today, demonstrations on fertilizing gains from chemical
fertilizer use in experimental fields are underway in many people's communes
by agricultural science researchers. These demonstrations instruct peasants
about how to rationally utilize chemical fertilizer; results have been good.
Propaganda and propagation functions need stressing to.allow users to under-
stand the characteristics and functions of various chemical fertilizers and

to master economical and rational fertilizer application techniques. This book
is written for this purpose.



[fable continued from preceding page/

Type of
chemical Appearance Solubility
fertilizer

urea completely

soluble
ammonium partially
calcium soluble and
nitrate partially

. precipi-

tated
sodium completely
nitrate soluble

calcium black or
eyanamide grayish

black with
carbide
odor
common partially
calcium soluble and
super- partially
phosphate precipi-
tated
concen- partially
trated soluble and
superphos- partially
phate precipi-
tated
Ca-Mg-phos- insoluble

phate

Thomas meal blackish insoluble
brown, high
specific
gravity

[fable continued on following page/

Mixing with

lime

ammonia
odor

ammonia
odor

without
ammonia
odor

without
ammonia
odor

without
ammonia
odor

- 60-

Heating, com-
bustion

fast melting
and glowing,
combustible
and release of
ammonia odor

External
observation
after other
processes

sour, astrin-
gent taste at
the tip of
tongue

gray or dark
green powder



2. Potassium nitrate: in rural areas, niter is mixed with pearl ash and
added to water. After screening, cooking the mixture solution within a pot
and letting it crystallize, the end product is potassium nitrate. This is
one of the composite fertilizers containing nitiogen and potassium nutrients.
In the industrial manufacture of potassium nitrate, first potassium chloride
reacts with nitric acid to yield a potassium nitrate solution, which is then
evaporated, crystallized and dried to obtain the end product.

Potassium nitrate is a grayish white crystal, containing 14-20 percent nitrogen
and 36-45 percent potassiun (calculated in terms of potassium oxide). Potas-
sium nitrate is not easily hygroscopic, but readily soluble in water. The
fertilizer is easily absorbed by crops, as being a quick-release fertilizer.
Upon heating, potassium nitrate will burn with bright. flane and smoke.
Therefore, potassium nitrate can be used as a raw material in the manufacture
of dynamite or firecrackers. Usually, the price of potassium nitrate is

high, so it is seldom used as a fertilizer.

Potassium nitrate is most suitable as a follow-up fertilizer in dry or wet
application. Dry, eight to ten parts fine,dry soil is mixed with the ferti-
lizer for scattering or furrow application. However, the application should
not be conducted after a rain or in the presence of dew, otherwise leaves
or stems will be burned if the fertilizer particles adhere to these parts of
the crop plant. Wet, 80-100 parts water can be mixed with the fertilizer
for spraying application or applying to the leaf surfaces.

Since potassium nitrate contains nitrogen and potassium nutrients and usually
a crop requires more nitrogen fertilizer than potassium fertilizer, the potas-
sium fertilizer will become a surplus and a waste if the amount is based on
the requirement of nitrogen fertilizer. So the amount should rest on the
requirement of potassium fertilizer and any deficiency of nitrogen nutrient
can be supplemented by a different nitrogen fertilizer. Usually, 20-40 chin
potassium nitrate is applied per mou.

The fertilizing effect of 1.5 chin potassium nitrate is about equal to a total
of 1 chin ammonium sulfate and 1 chin potassium chloride.

Here are precautions in potassium nitrate use:

(1) Potassium nitrate is best mixed with farmyard manure, like barnyard

manure and compost, to avoid loss of nutrients.

(2) Potassium nitrate should not be stored with flanmables, like gasoline,
diesel oil and coal, and its storage should not expose directly under the
sun to avoid fire risks.

(3) Potassium nitrate is best applied to upland fields with abundant irriga-
tion or rain because its fertilizing effect is lower when applied to lowland
field.

-~ 46 -



carbohydrates, some trace amounts of elements are essential; otherwise,
nutrient-deficiency diseases will appear. TIodine-deficient leads to

goiter and calcium-deficiency leads to osteomalacia. Crops require

minute amounts of elements that although there are some amounts in the

soil yet they may not be available to crops. Take boron as an example: only
3-10 percent of the total boron in soil can be absorbed by crops. So these
elements should be artificially supplemented and we call them trace element
fertilizers because of minute amounts required. The term "trace" does not
mean minute amounts in the natural environment but mean very minute amounts
required by crops.

Generally, trace element, fertilizers are those containing boron, copper, i
manganese, molybdenum and zinc. The need for these elements are only several
parts per 10,000 or even per 100,000; however, they have effects on crop
yield and quality. If there are no trace elements in the soil, a crop will
be plagued by various diseases and be stunted. If legumes are planted in
boron-deficient soil, root tubercle formation will be affected. If copper

is deficient, tobacco leaves will wither. If molybdenum nutrient is defi-
ecient, yellow spots will appear on leaf margins of the borecole plant and
the plant may not curl and become withering. Plant metabolism and soil
microbial activity and reproduction are closely linked to trace elements. :

The trace element fertilizers are best mixed with nitrogen, phosphorus and
potassium fertilizers as well as farmyard manure in application. Separate
application of trace element fertilizers is of course allowed; however,

this application tends to lead to waste because of the minute amounts needed.

Trace element fertilizers can also be used to soak (in the case of a solutim)
or be mixed with seeds to prevent seed diseases, to promote healthy germina-
tion and to cause vigorous growth. Generally, the seed soaking time is

2h hours but a longer soaking time is required if the crop has seeds with
tough hulls. The trace element fertilizer should be finely ground when
mixed with seeds. It is best mixed uniformly with dry, fine soil or powdered
tale before application. .

Here are principal trace element fertilizers:

1. Boron fertilizer: boron is also an essential element in crop growth and
maturation. Boron can promote metabolism and boost resistance to crop
diseases. In legumes, boron can promote nitrogen fixation in the atmosphere.
A boron-deficient crop will be easily affected by disease and their ferti-
lization and fruition are hampered. However, excess boron is harmful to
crops, even poisoning them. Generally, 0.1-1 chin boron nutrient is applied
per mou. Usually, boric acid and borax are used as boron fertilizer; these
are white crystal powder, easily soluble in water. Boric acid contains
17.5 percent boron and borax contains 11.3 percent. A by-product, boron-
magnesium fertilizer, when making borax, can also be applied in soil. This
fertilizer is 1.37 percent boron; the other contents are calcium and
magnesium, which also have a fertilizing power in crops.

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Section 2. Absorption of Chemical Fertilizer by Crop

After being spread to soil, first the chemical fertilizer dissolves in

soil water before crop absorption. Some chemical fertilizers dissolve rapidly,
so absorption is also rapid. Some fertilizers dissolve slowly, so absorption
is slow. Dissolving of a chemical fertilizer is closely related to pH,
microbe count, temperature, water content and mineral content in the soil.
Generally speaking, dissolution, absorption, redissolution and reabsorption
process in cycles. This does not mean that once a fertilizer is applied, it
is completely d‘ssolved and completely absorbed by the crop.

Usually, once applied to soil, the fertilizer is absorbed by the crop root
system. The roots can absorb waterand various nutrients since seedlings are
sprouted. We can see many fine hairs intergrown around the crop roots; these
fine hairs are called root hairs, growing close to the soil. In the central
part of a root hair is a long string of cells, hollow at the center like a
eapillary. Water is contained in soil particles around the root hairs and
mineral nutrients are in soil water. After the root hair absorbs these
substances, they are conveyed through the capillaries to stems and to leaves.

Besides water and nutrients being absorbed by crop roots, crop leaves can
also absorb water and nutrients. As a crop grows, leavés do many functions:
photosynthesis, respiration and evaporation. Besides, leaves can also absorb
nutrients. For example, spraying a dilute solution of calcium superphosphate
on the leaves of wheat plants causes the phosphorus nutrient to be absorbed
by the leaves. This absorption promotes formation and full growth of wheat
grains. This way of applying fert‘lizer is called fertilizer application
outside roots or at leaf surfaces.

Whether the root. system or the leaf surfaces of a crop absorb the nutrients
of the chemical fertilizer, nutrients rely on the leaf surfaces to be trans-
formed into numerous complex substances via photosynthesis. This organic
matter should be conveyed from leaves to various plant parts as nutrients to
satisfy the growth demand of cells in the crop plant. Or the organic matter
is brought to seeds or fruits as sugars, starch, protein, fat and fibers to
form the entire fruit. The content of this organic matter differs in dif-
ferent crops. Grain crops, such as paddy rice and wheat, contain more starch;
ed'ble oil-seed crops, such as rape seed and peanut, have more fat.

Some of the nutrients goes to the crop for consumption during crop growth;
the rest is stored for gradual consumption. Roots, stems, leaves, seeds
and fruits are places for the storage of nutrients. Seeds of wheat, paddy
rice, corn and sorghum, leaves of Chinese cabbage and borecole, and the fat
stem tuber of potato are depots for organic matter. Seeds of some crops
prepare to sprout after being sown the next spring, so essential nutrients
should be stored.

Section 3. Are All Nutrients in Chemical Fertilizer Absorbed by a Crop?

A chemical fertilizer should be dissolved and decomposed in soil before
absorption by crops. Then, after application to soil, can all the fertilizer

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