Authors: Professor Dr. Tasnee Attanandana
Dr. Prateep Verapattananirund
Professor Dr. Russell Yost
Illustrator: Wasinee Chantakorn

Part 1: Our Earth
It is a beautiful morning and Nidnoi is very excited because Uncle Pracha will takeher to his home in the country during the school vacation. Uncle Pracha brings
Pom, her cousin whom Nidnoi has not seen for a long time.
My parents often talk about Uncle Pracha being amodern farmer as well as a community leader. This
will also be my first trip to the country so I am
really excited.

Dingng.
do

Look!
they are here.

Hello Nidnoi, you’ve
already grown up
since I last saw you!

Hello Nidnoi.

Good morning
Uncle Pracha.

Good morning, Montri and Orr.
I would like to ask for yourpermission to take Nidnoi to
my farm for a few days.
Sure, Pracha. Nidnoi has
been so excited these lastfew days that she could
hardly sleep last night.

Nidnoi, be a good girl,and don’t be stubborn
or naughty.
Yes.

3

OK, children,
are you ready?
Yes,
we certainly are,Uncle.

tegs’t
Son ltehe car.
i
ye.
B
.
e
By

Have a safe trip.

Nidnoi,look at that. What?
Oh My,
it’s pretty.

This is so much fun. I have nevertraveled this far before. We are
passing beautiful scenery. I have
only seen waterfalls, mountains,and seas on television. This is thefirst time I’ve seen the real thing.

4

Nidnoi, you know, there areso many beautiful things in
our world! And they are evenprettier than on TV. Do you
know how the earth was made?

Over there isa fisherman.

No, Uncle,
how wasthe earthmade?

Our earth is about 4,600 million years old. Scientists believed that the earth used to bepart of the sun that later disintegrated and gradually cooled down. Its surface turned
into hard rocks but the inner core remained hot rock, so hot that it is molten like a liquid.
About 3,500 million years ago, one-celled organisms started to occur in the sea followed
by green algae and bacteria. About 1,150 million years ago hard-shelled animals including
mollusks, coral, and starfish began to appear. Plants attached to sea algae appeared 590
million years ago. They were brought to shore by sea waves where they became attachedto the rocks. The plants grew and spread. They helped cause the rocks to disintegrate
into soil.
590 million years ago
3,500 million
years ago

1,150 million
years ago

Plants and animals appeared on land and, together with warm
temperatures and water, aided in more soil formation. With the presence of soil, a variety of terrestrial plants and animals developed.
Dinosaurs and later human beings developed. The soil layers graduallybecame deep and thick. They supply four essential requisites ofhuman beings; food, clothes, home and medicine.

Children,our destinationis round thenext curve.

Part 2 : Soil
I like to grow trees. Trees help
make the air pure and cool.
Oh My! You have many trees
and it is so nice and shady.

5

Woof
woof!

Oh! I forgot to introduce
our companion. This small
dog is called “Jao Dang”

I took Jao Dang in when she
appeared one day in front of
the house. I was afraid shewould be hit by a car. She isa wise dog.

She really is asmart dog!

Ah! They are digging a new well. Look at the soil
which was dug up. The soil has many layers thattell us much about the possible uses of the soil
and sometimes, how it was formed.

6

OK. Children! Come this way.
I will take you to the farmers’
fields over there.
Wow!
This is so
exciting.

What are they doing overthere, Uncle? It looks quite
interesting.

Look at Jao Dang,
she is leading us to thefarmers’ plots.
Ha ha.

How cute!
Hi, Jao Dang.

We notice that the surface soil isoften darker in color than the deeper
soil layers. This darker layer is often
the result of old, disintegrated rock,residues from long dead plants
and animals

Soil layers
At the deep levels of the soil,
above the parent rock, the rock isdecaying and disintegrating.

At the deeper layers of soil,
even deeper than the parent rockyou can usually find the “bedrock”.
This is the rock layer that has not
yet decayed and disintegrated.
Most plant roots growand take up soil nutrientsfrom the surface soil
layer only.

Children, do you know why soil
is important for us?

The deeper levels of
soil, help support the plantroots and retain moisturethat can be used by
the plant.

It’s used for growing
vegetables and fruits.

Soils often differ in depth. In deep soils, where
the surface layers are thick, there is more
space for plant roots to absorb more nutrients
than in shallow soils where the surface layers
are thin.
It’s not only just for growing vegetables and fruits. Soil is thesource of four good things that humans need: food, clothes,home and medicine. In addition, soil is the life-base of farmers.
Soil is a little bit like the air we breathe, if we take care of it anddon’t destroy it, it will be with us all of our lives. Just like
we need to learn to keep air clean of smoke in order to use it,
we need to keep the soil in good condition so it can continue toprovide us with food, clothes, medicine, and a home.

Oh, I see.
So then how
is soil formed?

7

Soil has been developed from old,
decayed rock mixed with plant andanimal parts for millions of years. It isa natural resource that can not berebuilt. Soil is thus a valuable resourcethat we should maintain and conserve.

Oh My!
How do you know?
It’s wonderful
you understandso much!

My teacher has assigned
us to do a report on soils
during the school break.
That’s how I know.

Well! Excellent! So let me help you
remember by telling us again. Pleasetell me and Nidnoi what the soil ismade of.
Quite easy.

The soil is made of the following, whichhelps plants grow:Old, soft, decayedrock =45%
Old, dead anddecayed plants =5%

Each of theseparts of soil does
important things:

Water =25%
Air =25%

Water dissolves and carries

soil nutrients to plant roots where
they can help plants grow.

The old, soft,
decayed rock is asource of plant food.

Air gives oxygento plant roots forrespiration.

Old, dead and decayed plants

help the soil become loose, stay moist,and be easy for roots to grow in,they are also the food for tinysoil animals and plants.
8Very good.
Wow! Pom knowsa lot about soil!

Good soil has
four things about it,
isn’t that right, sir?

Eh! How can weknow which soil isgood, sir?

Pom, can you
answer that?

Yes,very easy.

(2) A good soil is not acid, or alkaline or salty,(nothing that stops growth, good chemical properties)(1) A good soil has plentyof plant nutrients (plentyof “food” for plants!)(3) A good soil is easy forplant roots to grow in,(loose and easy forroots, good physicalproperties(4) A good soil has small creatures that help the plant grow,(many small helpful creatures, good biological properties)

You are right, Pom.
Good soil or soils whichplants grow well should
be like that.

That means we add fertilizers to soil
in order to add more plant food so plants
can grow bigger and stronger. This helps
the soil become more fertile, right?

Therefore, adding fertilizers (plant food) helps plants
grow but the soil needs to be loose and easy for roots
to grow in, have none of the things that stop plantsfrom growing, and have many small helpful creatures.

9

So you mean that a fertile soil is notalways a good soil, but a good soil must
be a fertile soil. It sounds a little
complicated.

??

chemicalfertilizers

Does the soil contain sufficientplant food? We must determine
how much plant food the soil
contains: what levels, if low, chemical fertilizers should be appliedcompost green
manuremanureIs the soil loose and easy for roots togrow in?“ Soils that are so hard thatwater does not soak in will not allow
roots to grow normally. Dead and decomposed plants and animal parts; compost,
manure and green manure should be
added and mixed into the soil.
10

We have to start by determining whichof the four things about soil causes it to
be a poor soil, and then we can improvethose things. We start by asking
questions. For example:
So how do we improvea poor soil, sir?

marl

Is the soil too acid or alkaline? If the soil isacid, then marl or a limestone material canbe added (liming). If the soil is too alkaline,
then treat the soil with an acid material. If
the soil is too salty, the salt must be removed,
perhaps by applying lots of water so thatthe water moves down through the soil.

old, dead anddecayed plants

Does the soil contain many small creatures that
help plant grow? Soils usually contain many tinyplants and animals, many of which are so smallthat they can not be seen. The bacteria mixed
with legume seeds prior to planting will help plantobtain food from the air. The old, dead unused
plant and animal parts can be added to the soil
to increase the food for bacteria.”

Soil in the forest usually is fertile because the tree roots take up nutrients fromthe soil to grow the leaves, fruits, stems and branches, and when the trees die,these plant parts fall onto the soil and decay, nutrients are released and become
ready for use by new plants. When it rains, such nutrients will be removed to thedeeper layer of soil as the water flows through the soil. From there, new plantroots will again take nutrients up for their growth. This cycle will go on and on.
Why is soil in the
newly opened forest goodfor growing plants andproducing good yield, sir?

nutrients

In soils used for agriculture, the nutrients are used up by the food plants andwhen we collect the food plants, we also take away the nutrients in the plants fromthe soil. In this way the soil loses nutrients because they are taken away in thefood plants. So, without returning nutrients, a good agricultural soil can eventually
become poor soil.

Do the different kinds ofplants use different amountsof nutrients, sir?

11

Different plants need different kinds and also different amounts of nutrients.
For example: 1 ton of rice grain removes 12 kg of nitrogen, 3 kg of phosphorus and 3 kgof potassium from the soil where it is grown. There are even more nutrients removed in
the straw, stem and roots needed to produce the rice grain. Therefore, returning thestraw, stems, and roots to the soil helps to keep the soil fertile.

Nidnoi, if you don’t
understand anything,please ask.

(Scream!!!)earthworms!

Yes sir.

Be careful!. Try to avoid stepping on earthworms. Please do not be afraidof them. Did you know that earthworms are some of the many small creatures that are useful to soil? Earthworms loosen up the soil and improve it
since they dig through soil making the soil loose, more open, and easy
for roots to grow in. When earthworms die, they will be decomposed
and return the nutrients in their bodies to the soils.

Ha, Ha! Nidnoi,
are you afraid ofearthworms?

What about nutrients in
soil, where do they originallycome from? Pom.

Soil nutrients (plant food) come from rock that becomes old and soft, soil minerals,
plant and animal residues. Soil in newly-opened forests is usually good soil withlots of plant food, water, and air which help plants grow well.

nutrients
12

nutrients

When forest is prepared for agricultural use, not only is the plant food removed when crop
plants are harvested and the food is eaten, but nutrients may be lost from the area when rain
seeps into the soil or when the rain carries soil away during a storm. The loss of soil nutrientsin surface soils may result in the loss of so many nutrients that the plant no longer grows well..

Uncle Pracha,
what are the essential
foods for plants?

Plants need 17 essential nutrient elements-Air and water : provide the elements carbon, hydrogen,and oxygen.
-Soil: provide nitrogen, phosphorus, potassium, calcium,magnesium, sulfur, iron, manganese, zinc, copper, boron,
molybdenum, chlorine, and nickel.

Amazingly, the soil usually contains
enough of the elements or plant foods forgood plant growth. Of the large number of elements mentioned here there
are three that are special because
they are needed by plants in large
quantities and often soils do notcontain enough of these elements
for the plants to grow attheir best.

That’s right. Every nutrient elementthat we have mentioned is equallyimportant. Without even one of theseelements a plant cannot grow. You will
be interested to know that each ofthese nutrient elements
is used in different waysby the plants.

This I know, sir.
I have learned
about this in
my class about
agriculture

Nitrogen (is shortened to N),

phosphorus to P,
and potassium to K.
This makes it easier toremember (NPK)!

Children, are you tired yet?
Let’s rest over there and then I
will explain about the nutrients,
Nitrogen, Phosphorus, andPotassium, and how the plantuses them differently.

13

Nitrogen helps
plants become strong
and increase crop yield.
Plants can not growstems and leaves without
it. If there isn’t enough,the yield decreases. On
the other hand, if there
is too much nitrogen,the plant may growtoo fast, become
weak and fall over.

Potassium helps plants growstrong stems and helps theplant resist diseases andinsects. If there is not enoughpotassium in the soil, in thecase of rice, more unfilled
grains will be obtained. If
potassium is not enough for
corn, there also will be grainthat does not complete its
growth and the cob may haveno grain in some places.

Phosphorus helps the growing roots, flowers, and making grain, fruits, and other plantparts. If there isn’t enough phosphorus in the soil the plants will be small and have thinstems, will not flower as early, and the grain or fruits will not ripen as fast as normal.
Yay, very good indeed. Uncle Pracha
has made it easier to understand in
this briefing than reading by myself.
Ha, Ha, I am going to put what Uncle
Pracha told us in my report.

Pracha, why canPom, why didn’t you Uncle
plantsgrow better in loamy
read it yourself?
soils than in clayey or
sandy soils?

The way sandy, silty and clayey soils are different from one another is because of
the size and how the soil particles fit together to form spaces in the soil or pores.
- Small pores or micropores are filled with water and may hold the water too
tightly for the plants to use.
- Large pores or macropores are filled with air, not water, and therefore, do
not hold water for plant use.

Well-structured or loamy soil has about 50% pores. One half may be small pores while
another half has large pores. About 45% of the soil is composed of old, decayed,
crumbled and crushed rock. The remaining 5% is old dead plant and animal parts.
14

“Soil texture” is a scientific word that tells us about the size of the soil particles. It tells
us how a plant might grow in the soil, particularly in terms of nutrients and water. A soil
usually has particles of sand, silt, and clay, with sand being the largest, silt particles are
smaller than sand, but larger than clay. Clay-sized particles are the smallest of all.
A clay soil usually has more clay-sizedthan the other particles. ThisA clay soil may particles
means
clay
will have more micropores,
have as much as 50% will be able soil
to hold more water and releaseclay-sized, 30% silt- more nutrientsplants than sand. On thesized and 20% sand- other hand, claytosoil
usually has a few macsized particles
ropores (large sized pores) and this may
cause good aeration but less water andmore drainage.

The size rangesof soil particles :A silt soil may have
25% clay-sized, 35%
silt-sized and 40%
sand-sized particles.

Thus a silt soil has about the sameamount of sand, silt, and clay particles. This type of soil has nutrients,
water and air in the ratio suitablefor plant growth.

Finally, a sandy soil
may have 10% claysized, 20% silt-sized
and 70% sand-sizedparticles.

A sandy soil has more sand-sizedparticles, thus has fewer micropores
resulting in low water and nutrients holding capacity, and is less suitable for plant
growth. However, sandy soils have many
very large pores that do not hold water forplants and may have a drought problem.

clay-sized particles :<0.002 mm

Question! Why does soil used in
growing rice form big cracks whendry, sir? I have seen this on TV.
Rice fields, after harvesting,appear to be dry withmany cracks.

silt-sized particle
0.002-0.02 mmsand-sized particle
0.02-2.0 mm

Most soils used for rice are clayey and containa type of clay that swells when wet and shrink
when dry, thus we see the result of shrinking,which is why soil cracks when it dries.

15

Part 3:

Fertilizer
Uncle Pracha sir,what is fertilizer?

How many kinds of plantfood or fertilizer do weusually apply in the soil, sir?

Fertilizer is a powder or a granulethat is applied to the soil that contains
the essential plant foods or nutrientsrequired for plant growth.

The popular type of fertilizer used
are chemical fertilizer, organic fertilizer and bio-fertilizer. In a minute,
I will take you to the fertilizer
warehouse to show you different
kinds of fertilizer.

Organic fertilizer is made from living organisms;
examples are compost, manure and green manure.
When organic fertilizer is applied to the soil, it
slowly releases plant nutrients and also improve
the soil structure, water drainage and aeration. As
a result plant roots can grow easily
into soil that has been fertilized with fertilizer
warehouseorganic fertilizer.

However, organic fertilizer usually contains lower amounts ofplant food than chemical fertilizers. After organic fertilizer isbroken down or consumed by soil organisms the plant nutrientsare released in the same form as chemical fertilizer and thenplant roots are able to use the nutrients for growth.

fertiliz
warehoueser
16

ManureManure is an organic fertilizer which
is animal droppings from ducks, chickens,pigs, buffaloes, etc. Animal manure willoften contain 0.5% nitrogen, 0.25% phosphorus and 0.5% potassium.
The amount of nutrients in animal manure
depends, partly, on the kind of foods the animaleats. New or fresh manure fertilizer usually has
more nutrients than manure that has been stored
for a long time. Also a caution, manure stored orplaced outdoors could lose nutrients to rain or to
the air as gas.
Therefore, manure should be placed undera roof protecting it from sunshine and rain.
Fresh manure can be harmful to plants since
it is not fully decomposed. Fresh manures canbe mixed with plant residues, e.g. rice husk,
straw, sawdust, etc., for a while or sun-dried
before use.

CompostCompost is an organic fertilizer resulting
from the composting process. Compost may
be formed from dry grass, leaves, ricestraw, food remnants, garbage as well asother organic materials.
The farmers can make their own compost by
making a heap of plant residues or other organic
materials 30 cm above ground, stomping on it until
compacted, apply thin layer of manure including
1.5-2.0 kg of 15-15-15 chemical fertilizer for 1 ton ofplant residues, watering and the second layer ofplant materials is placed over followed by manureand chemical fertilizers as the first heap.

The process is continued till a heap of
1.5 x 2.0 m is obtained. On the top layer, soil
is placed after which intermediate watering
is made followed by covering it with grass or
rice straw. The heap must become hot in orderto kill harmful bacteria and micro-organisms.
17

Green manures – theseare fertilizers made from fresh plant parts such as leaves,stems, and roots.
Green manures are often legumes, such as
Vigna, Sesbania, and Crotalaria. These plants
are grown to the flowering stage and thenare ploughed into the soils. After a shortperiod of a week or so the main crop can beplanted to take advantage of the nutrientsreleased by the green manure.

N = 75-94 kg/ha

Legumes can be planted in an area of
1 hectare, and may produce as muchas 3.1 tons of dry plant. This amount oflegume plant may add as much as 75 to
94 kg/ha of nitrogen to soils

The best green manures are legumes which
grow fast and have dense leaves andbranches that can compete with weeds.
They should also have strong root systems
which can grow deeply into the soil.

Normally compost contains 1% nitrogen,
0.5% phosphorus, and 0.5% potassium. Thismeans that in 100 kg of compost there willbe 1 kg of nitrogen, 0.5 kg of phosphorus, and
0.5 kg of potassium. The quality of compost
depends on materials used in thecomposting process. For example:

How much nutrient
is in compost andmanure, sir?

100 kg of rice straw
contains 0.6 kg nitrogen, 0.1 kg phosphorus,
and 1.7 kg potassium.
100 kg of rice husk,
no nitrogen,0.2 kg phosphorus,
and 0.8 kg potassium.

100 kg of chicken
manure contains
2.4 kg nitrogen,6.3 kg phosphorus,and 2.1 kg potassium
18

Therefore, replacement of the nutrients removed ina food crop often requires a large amount of organic
fertilizer, be it compost, green manure or manure.
Such large amounts of organic fertilizer may not beeasy to find or transport to your farm.

And what isbio-fertilizer, sir?

Wow, too many numbers! I am
already confused. In conducting
agricultural work, we’ve got to begood in mathematics too.

Bio-fertilizer is a fertilizer composed of living
microorganisms (plants and animals so tiny that you cannot
see or identify them). These microorganisms do special
things, that is, they can change the forms of plant
nutrients so that plants can use the nutrients..

Some examples of this kind of microorganisms are rhizobium in legume root nodules,
frankia in Casuarina root nodules, and blue-green algae in leaves of the tiny azolla fernthat grows on water. An example of microorganisms which can change the form of plant
nutrients from unavailable to be available is mycorrhiza fungi, a beneficial type of fungi,
which can dissolve phosphorus that plants can not use due to the chemical form in thesoil making it so that plants can absorb the phosphorus.

frankiarhizobium

Bio-fertilizer

blue-green algae

mycorrhiza fungi
19

A “Fertilizer material” is chemical substance with at least one important nutrient.
Usually the fertilizer material can dissolve in water, which is necessary for plants
use the nutrient. “Fertilizer materials” can be directly used or they can be mixed
with other fertilizer materials in “bulk blending” process.

Nitrogen fertilizer materials: Urea,
the chemical formula: (NH2)2CO (46-0-0).
Another N fertilizer material is ammonium
sulfate with the chemical formula of(NH4)2SO4 (21-0-0).

Phosphate fertilizer materials: Triple
superphosphate, which. has a chemical
formula of Ca(H2PO4)2 2 H20 (0-46-0).
Another phosphate fertilizer: Diammonium phosphate or DAP, whose chemical
formula is (NH4)2HPO4 (18-46-0).

Potassium fertilizer materials include
Potassium chloride, whose chemical
formula is KCl (0-0-60) and Potassium
sulfate, whose chemical formula is
K2SO4 (0-0-50).

The second type of chemical fertilizers is the “Mixed
fertilizer”. They are chemical fertilizers obtained
from blending at least 2 “Fertilizer materials” together.
Such fertilizer will contain nitrogen, phosphorus
and potassium nutrients at the required amounts.

21

We can illustrate how mixed fertilizers are made. A mixed fertilizerof 17-17-8 can be made by mixing 22, 37 and 14 kg of urea,
diammonium phosphate and potassium chloride, respectively.
A mixed fertilizer of 17-17-8

22 kg

37 kg

14 kg

urea
(46-0-0)

diammonium phosphate(18-46-0)

potassium chloride(0-0-60)

There are several ways that fertilizers can be handled. These include
granule, powder, and liquid forms. There are also 2 forms of mixed
granule fertilizer.

22

The first form is compound fertilizer.
The fertilizer materials are mixed
and ground, then made into granules.

The second form is bulk blend
fertilizer. The fertilizer materials
which have similar sizes are mixed
and used directly.

When I studied agriculture, my teacher told
me that a fertilizer will have a label on the
bag with three numbers. Are these numbers
a fertilizer formula, sir?

That’s right. A fertilizer formula isthe numbers showing the amountsof nitrogen, phosphorus, andpotassium in the respective chemical
forms as N, P2O5, and K2O inrespective weightpercentages.

I’ll give you an example. 15-5-25
fertilizer formula means 100 kg
fertilizer has nitrogen, phosphorus,and potassium nutrients of 15%N,
5%P2O5 and 25%K2O, respectively.
Therefore, when the farmer buys 100
kg fertilizer, he will get only about
45 kg of nutrients.

100 kg fertilizer
15-5-25
N, P2O5, K2O
15 + 5 + 25 = 45
Therefore, the farmer gets
45 kg of nutrients

I have also heard
about fertilizer ratio,
what does thatmean, sir?

Ah yes, fertilizer ratio is the ratio of N-P-K in
fertilizer. Although fertilizer formulas are different,
if they have the same ratio, they are considered tobe the same kind. The only difference is theconcentration of total nutrients in eachfertilizer formula. Hence, they can easily
be substituted one for the other.

Now, I’ll give you a quick
calculation. Whoever can answer
first, will win an ice cream.
Good, sir

Yay,
ice cream23

Who knows what theratio of fertilizer in
16-8-8 formula is.

I do sir. 16-8-8 formula means
the amounts of N, P2O5, K2O in
100 kg with the ratio of 2:1:1.

2 divides…

If it is 20-10-10
formula, what is its
fertilizer ratio?

I got it! 20-10-10 formula has
the same ratio as 16-8-8 formula,
2:1:1 but 100 kg of 20-10-10 willcontain more actual nutrient
than 100 kg of 16-8-8.

I surrender
woof!

Ha Ha Ha! Nidnoi, very good.
Pom, why you are so quiet?
Where is your calculation?

I gave up in the calculationcompetition. If it was an eatingcompetition, I would win
for sure!

24Uncle Pracha, howuseful is the fertilizer
ratio, sir?

Fertilizer ratio can help us in selecting various
fertilizer formulas for the most suitable use asrecommended in fertilizer application.

For example: In the recommendation to use 50 kg/ha of 16-8-8 fertilizer formula,which is the low fertilizer formula of 32% nutrients, it can be substituted with only
40 kg/ha 20-10-10 fertilizer formula having 40% nutrients. Both give the samerequired amounts of nutrient.

This also gives
the same result.

40 kg

50 kg

20-10-10

16-8-81 hectare

In addition, a fertilizer
ratio can give a hint as tothe intended purpose of
the fertilizer.

A Fertilizer ratio with a high first number, such as
2:1:1 of 20-10-10 formula will help increase vegetativeplant growth.

A Fertilizer ratio with a high last
number, such as 1:1:2 of 10-10-20
formula will help on plant quality.
I have already learned somuch. How can “Fertilizer
materials ” be made for thebulk blending of fertilizers,sir?

A Fertilizer ratio with a high middle number,such as 1:2:1 of 10-20-10 formula will help
the functions of fruiting and root growth.
25

Let’s go that way, children,
I am going to show you
how to calculate themixing of fertilizer.

For an example of mixing
chemical fertilizer according
to the fertilizer recommendation from soil analysis,
we will use “Fertilizer material”
sold in the market, such as
18-46-0, 0-0-60 and 46-0-0,
etc.

Are you ready, students?
Yes,
we are, sir.

Fertilizer recommended for rice will be shown in nutrient
weight per area (kg/ha). For example, the recommendationof N-P-K is 50-25-50 kg/ha, respectively. However, it isrecommended to apply N twice, each time of equal weight,that is at the time of planting and top dress application
before flowering since N is easily lost.
Method of application
N P2O5 K2O
1. To be put at the same 25 25 50 kg/hatime of planting
25
0 0 kg/ha
2. Second time,
top dress
50 25 50 kg/ha
Totaling

As for the calculation method, the needed nutrient P has to be calculated first which equals to 25 kg/ha using “Fertilizer material” DAP or
18-46-0.
Then 46 kg of P2O5 isderived from 100 kg of
18-46-0 fertilizer, and if
25 kg P2O5 is needed as
18-46-0 fertilizer then we have25/0.46 = 54.3 kg of the
18-46-0 fertilizer has
to be applied.
26

The 54.3 kg fertilizer has N in it.
One hundred kg of 18-46-0 has 18
kg N. Therefore, 54.3 kg of 18-46-0
will contain N equaling to
0.18 x 54.3 = 9.8 kg

Therefore, 54.3 kg of 18-46-0
will give 9.8 kg N. However, in thefirst application we have toapply 25 kg N, so how much N
is still lacking?

Next is46-0-0.
That’s right,
Nidnoi.

In the first application, we arelacking 25-9.8 = 15.2 kg, sir.

Remember 46 kg nitrogen is derived from 100 kg of
46-0-0 fertilizer formula. If 15.2 kg more nitrogen isneeded, 46-0-0 fertilizer formula of 15.2/0.46 = 33.0 kg
weight has to be applied.

15.2/0.46 = 33.0 kg

Also remember that 60 kg potassium is derived
from 100 kg of 0-0-60 fertilizer formula. If 50
kg of K2O are needed, 0-0-60 fertilizer formulaof 50/0.60 = 83.3 kg has to be applied.

Since we divide nitrogen fertilizer into two applications,each of 25 kg, hence, it has tobe calculated as to how muchof 46-0-0 fertilizer is needed
to get 25 kg for the second
application.

50/0.60 = 83.3 kg

27

Remember that 46 kg nitrogen is derived
from 100 kg of 46-0-0 fertilizer. If 25 kg
nitrogen more are needed, 46-0-0 fertilizer
formula of 25/0.46 = 54.3 kg has to be applied.

So who can come up with the answer
to how much fertilizer is required for1 hectare of rice according to such
recommendation?

Yes, I can, Uncle Pracha. In the first fertilizer application, we blend 54.3, 83.3 and 33.0 kg of
18-46-0, 0-0-60 and 46-0-0 fertilizer materials, respectively, together which we will get
N-P2O5-K2O of 25-25-50 kg per ha, respectively. As for the second application, 54.3 kg of
46-0-0 is to be used in order to obtain the recommended nutrients in fertilizer application
for rice. That means N-P2O5-K2O will equal to 50-25-50 kg per ha, respectively. Is thatright, Uncle Pracha?

That’s right Nidnoi,
very good indeed,
my niece.
Good
indeed.

Besides, children, you should be very careful whenpurchasing fertilizers. The prices of fertilizer per
nutrient unit have to be calculated when buying
chemical fertilizers. The price per bag can be awrong way to compare fertilizer costs.

Most farmers tend to make decision on buying fertilizers by the cheaper bag
prices because of misunderstanding. The right thing is to calculate the price per
nutrient unit in fertilizer. One bag of fertilizer may have a higher price, but if it
contains a higher percentage of fertilizer it might be cheaper per unit of nutrient.
So be careful and consider the price per unit of nutrient in the fertilizer.
I will give you an example:
cheap
28

expensiveThe first example is to compare the price of two bags of fertilizer
material containing nitrogen. The two bags have labels of 46-0-0 and
21-0-0. The prices are $473 and $250 per ton, respectively
To calculate the price on the per unit of nutrient basis do the following:

The fertilizer 46-0-0 costs $473 per ton which means 1000 kg
fertilizer has 460 kg nitrogen costing $473.
Therefore, the price of 1 kg nitrogen is $473 /460 = $1.02
VSThe fertilizer 46-0-0
that costs $473 per ton

The fertilizer 21-0-0
that costs $250 per ton

The other fertilizer with the label 21-0-0 costs $250
per ton which means 1000 kg fertilizer has 210 kg
nitrogen costing $250. For this fertilizer the cost perunit nutrient is 250/210 = $1.19.
The result is that the 21-0-0 fertilizer
will cost more than 46-0-0 fertilizer, eventhough the price per ton is less for the
21-0-0 fertilizer.

Let’s look at another example,
children. Let’s compare pricesof 15-15-15 and 10-10-10 fertilizer for example. We learn
from the fertilizer store thatthe cost of the two fertilizers,
15-15-15 and 10-10-10, is $673
and $460 per ton,
respectively.

Oh Wow! If it is notworked out by
calculation, we will
never know.
Yes,
yes.

We carry out the calculations as follows:
15-15-15 formula costs $673 per ton which means
1000 kg fertilizer has 450 kg nutrients costing$673. Therefore, the price of 1 kg combined N,
P2O5, K2O equals 673/450 = $1.49

29

The other fertilizer, 10-10-10, in our example
costs $460 per ton which means 1000 kg
fertilizer has 300 kg nutrients costing $460.
Therefore, the price of 1 kg of combined N,
P2O5, K2O equals $460/300 = $1.53

Our calculation of the the cost offertilizer on a nutrient basis tells us the
surprising result that although the cost
per ton of the 10-10-10 fertilizer is lessthan the price per ton of the 15-15-15
fertilizer, it actually is more costly when
we compare the costs per unit nutrientin the fertilizer.

10-10-10

15-15-15

The last example is the calculation of plant nutrient
costs in organic fertilizer. In our example we learn thatorganic fertilizer, with a label of 2-1-1 costs $233 per
ton. This means 1000 kg of organic fertilizer has 40 kg
nutrients. Therefore, 1 kg nutrient is equal to$233/40 = $5.82.
This detailed comparison of the cost on a nutrient
basis shows that in this example, organic fertilizer ismore expensive than chemical fertilizer.
organic
fertilizer

chemicalfertilizer

There is one additional thing to consider about organic fertilizer. All 40 kg ofnutrients in 1 ton of organic fertilizer usually is not available to plants because
they are in the form of an organic compound. The organic fertilizer must decompose and decay to simple inorganic nutrients by microorganisms before the plant
can actually use them. Organic fertilizer may release only 10-70% of total plant
nutrients in the first year. This depends on the kind of organic fertilizer and soil
condition.
1 ton oforganic
fertilizer
30

decomposing

an organic
compound isconverted toinorganic compound

Organic fertilizer may
release only 10-70%
of total plant nutrientsin the first year.

So should the farmers
buy mixed fertilizers or
fertilizer materials to preparebulk-blending fertilizers
themselves?

Preparing bulk blending fertilizer is a way forthe farmers to apply fertilizer effectively,
moreover, the cost is cheaper because theexpenses on granulation and marketing are
included in the price of “compound fertilizers.”
marketingcompoundfertilizers

Then the farmers should buy “Fertilizer
materials” to make bulk-blended fertilizer
themselves. It is not only that the farmers
can get the required formula as needed fortheir plants and soils, but also this helps insolving the problem of low quality or
fake fertilizer.

From what I have learned from Uncle Pracha, I
still don’t understand why some people do notsupport chemical fertilizer use. Is it because
chemical fertilizers are as toxic as pesticides?

Therefore, the government should
encourage more selling of“Fertilizer materials” so that thefarmers can prepare bulk-blended
fertilizers themselves.

OK, Pom,
can you
answer that?

31

Oh
My!

Pom has fallen asleep!
Hey Pom,wake up!

z..

Boy! I don’t know when I
fell asleep. Where wereyou, Uncle Pracha?

OK, Pom, answer Uncle
Pracha. Why do some people
support the use of chemicalfertilizer why others do not.
Do chemical fertilizers havetoxicity similar to pesticides?

Chemical fertilizers are not toxic. They
have different functions from pesticides.
Chemical fertilizers supply plant food.

What?

I can answer
that sir. I learned it
in my class on
agriculture.

Pesticides are also chemicals, butthey help protect plants, grain, andother food from diseases, insects
and weeds.

ferCthemic
ilize alrs

pesticides
That’s right. Most pesticides are alsochemical compounds, which, when notcarefully used, can be harmful to thehealth of users and consumers and cancause environmental pollution. Hence,
they have to be used with great care.

32

I get it, sir.

Ah Yes! Pesticides then must have warning labels.
For example: Fresh produce should be harvested only
several weeks after spraying in order to reduce toxic
residue to the level of no hazard to theconsumers, etc.
WarningChildren, Let’s take awalk outside, so you canbe fully awake.

Yes,
that’s right.

Part 4 : Efficient Fertilizer Applications
Yes sir.

Yes sir.
Ah! Uncle Pracha,is that Uncle Chom?

Good morning,
Uncle Chom.

Good morning,
Pracha andchildren.

Good morning,
Uncle Chom. Good morning,

Uncle Chom.

33

You must be Nidnoi, Uncle Pracha told
me he would bring you to the farm.
How is your visit? Are you having
a good time?
I’m having a very good time,indeed, sir. Today Uncle Pracha hastaught me and Pom about soil andfertilizer. I have learned many new,interesting things.

Uncle Chom, I am taking the children tolook around. Would you care to join us?
Sure. I have justfinished watering myvegetable plots.

It is because after a long time using soils to grow food,the nutrients in the soil become used up and plants
grow more slowly. This may occur when the soil nolonger has enough nutrients for the plants to use ingrowing. For this reason, the application of chemicalfertilizer, is essential especially N-P-K.

Uncle Chom and Uncle Pracha,
I still wonder that if we alreadyhave compost, manure and biofertilizer, why do we have to use
chemical fertilizers in growing
food crops?

34

Aside from this,chemical fertilizers usually
have a lower cost because
the amount of required
nutrients can be accurately
calculated and easily
obtained.

The organic fertilizer has a lower content of
nutrients. If it is applied alone, a large amount oforganic fertilizer is needed. The high transportation costs to bring the organic fertilizer to thefield is another limitation. However, in continuous
use, organic fertilizer will improve soil aerationand loosen the soil for better plant root growth,
resulting in the efficient use ofchemical fertilizer.

To sum it up, chemical and organic
fertilizers used together will give thebest results.

Yes, it is like that.

But how do the farmers
know when to use chemical fertilizers, what kind,
how much and what
method should be used?

Costs of adding fertilizer follows “the law ofminimum”. This law means the most deficient nutrient
element will be the one limiting plant growth. So it’s
important to add the most limiting nutrient when
fertilizing. However, the farmers have to know thefood plants they wish to grow and also know
their soils.

Determine thelimiting nutrient35Uncle, sir, the other day I
read about something called “soilseries identification”. What is “soilseries identification?” How can it
be used? What is it based on?
Plants grow better in some soils than in others. Soils in Thailand have been identified
and given names to help others know and discuss their properties. The Land Development Department has identified 240 types of agricultural soils in Thailand. These soil
types are called “soil series.” The soil properties that do not change quickly (soiltexture, soil color, depth, pH, etc) were used for identification. These properties
usually stay the same for many years or decades, although the amountsof nutrients in soils can vary with how many crops are grown and how
much fertilizer is applied.

soil texture

soil color

5
10
15
20
soil depth30

Therefore, if chemical fertilizers areto be used efficiently, the soil type,especially the “soil series” should be
brought into consideration. Each soil
series has a name. Just like Pomand Nidnoi!

soil pHSo, after we have learned thename of our soil series, how much
fertilizer should be applied?

Farmers can learn which and how much nutrients should be applied byanalyzing their soil before planting. They also need to know which food plantthey want to grow because each plant needs different kinds and amounts ofnutrient elements. Soil scientists have already conducted experiments to findout how much fertilizer should be applied after soil analysis.

36

Farmers must apply fertilizers at the right time and in the rightamount so that the plants have nutrients which they need for
growth. This means it is important to understand how plants
grow and use nutrients. It depends on the duration ofplant development.
After we have learned how much
fertilizer should be applied, howabout the method of application?

What is the concept of efficientuse of fertilizer, Uncle?

This simple idea begins byobserving and knowing the kindof soil to be used. For example, if
the soil is compacted, it should beloosened and possibly organic
fertilizer should be used. If thesoil does not have enoughnutrients, then chemicalfertilizers are needed.

It is a simple idea, Nidnoi. Please
remember: efficient fertilizer
applications must be “the right kind,the right amount, the right time andthe right method”.

In simple terms the amount of
nutrient the plant needs should bematched with the amount of nutrient thesoil can supply. The nutrient that the soil
cannot provide then need to be added insome form, probably with a combinationof chemical and organic fertilizers.

37In addition, children, we
have to apply fertilizer
at the right time by theright method.

Right kind, right amount,right time, and right method.
We can remember now, sir.

By the way, plant residues should be incorporated into the soil when they arepresent. Green manure and manure should be used for soil improvement; suitable bio-fertilizers will help in reducing the use of chemical fertilizers.

Will chemical fertilizers
pollute the soil?

No, they won’t, Nidnoi, but too much nutrient can hurt
the food plant. For example, too much nitrogen fertilizer
may cause the plant to be weaker, produce too many
leaves. As a result, insects and disease damages will befollowed. When too much nitrogen fertilizer isapplied the excess is easily leached down into
underground water and to canals and rivers.
The water becomes polluted.

Nitrogen coming from animal manure, garbage and dirty water from
communities, without good management, will also pollute the environment.

38

I will tell you a story. If the rice farmers use too much nitrogen fertilizer, it may
give some disadvantages such as rice plants fall before they can be harvested
and yield decreases. Insects and diseases may follow resulting in more
pesticides application, higher production cost and grain no longer safe forhuman consumption.

Too much phosphorus and potassium fertilizer does not turn good soil into bad soil.
These fertilizers, however, can accumulate in soil but have no benefit, thus wastingmoney. The right application of fertilizer is to apply only the deficient nutrients.
We can’t
use this up

No.

This istoo much.

Chemical fertilizers are not the causeof bad soil. Incorrect application, however,can result in a degraded environment.

Question: Can chemical fertilizer make soil hard?

39

Applying chemical fertilizer is not the cause of hard soil orcompacted soil. Hard soil or compacted soil can happen in many
ways, such as, soil ploughing with a big machine or buffalo, or
tilling when the soil conditions are not suitable.

Hard or compacted soil can result fromlosing topsoil. For example, soil erosion canoccur in sloping areas when it rains heavily,
or in soil preparation. In such cases, topsoil is removed exposing a layer of subsoil
which may be hard and compacted.

Children, the reduction in
the amount of organic matterin soil can also result in hard,compacted soil.

topsoilsubsoil
Organic matter in soil usually decomposes over time.
When soil has been used to grow food plants for along time, even in pots, there will be a decrease in
the amount of organic matter. The loose soil gradually
becomes compacted, hence, it is essential to regularly
add organic materials to maintain a loose soil.
compacted
soil

40

Now
I understand.

Nidnoi,isn’t itfun?

Today, I am very happy that I took this trip with Uncle
Pracha and Pom. I have learned so much about soils. If I had
stayed in Bangkok, I do not think I would have a chance to
see all these things. I have to thank Uncle Pracha and Uncle
Chom as well as Pom. This school break is the best one everfor me.

In the next school break, I
would like to come back here
again. May I bring along myfriends?

I also have some gifts for your parents.
I can see that there is not much space atyour house to grow plants, so I will try tochoose some potted-plants for you. Is it
alright?

Certainly, Nidnoi.
You are always
welcome here.

You can bring all
your friends, so I
will get to make newfriends as well.

Oh My! It’s very kind of you,
Uncle. I just want my home tobe as shady as your farm house
here. In Bangkok, there are notmany trees and it is quite hot.

41

Besides, here there is
Jao Dang to play with. At my home,
we don’t have enough space to keep
dogs. I have to play with the small
dog at my neighbor’s house

So you have to come here often.
We’ve got to go now; Pom and Nidnoi
must be hungry already

Aunt Kaew should havefinished cooking dinner
for us by now.
I am very
hungry.
Ha Ha.

42

Professor Dr. Tasnee Attanandana
Education
B.S. (Hons.) Kasetsart University
M.S. University of the Philippines
D.Agr. Kyoto University

Experiences-Professor of Department of Soil Science, Kasetsart University-Site-specific nutrient management-Domestic wastewater treatment using Multi-soil-layering system-Team leader on KU soil test kit development
Dr. Prateep Verapattananirund
Education
B.S. Kasetsart University
M.S. Chiba University
D.Agr. Kyoto University

Experiences-Researcher, Department of Agriculture-President, Eco-community Vigor Foundation-Consultant, Pan Group-Sustainable agriculture development, building capacity of farmers,
farmer networking, human resource development, participatory
strategic planning (Smart planning)
Professor Dr. Russell Yost

Education

B.S. Kansas State University
M.S. University of Nebraska-Lincoln
Ph.D. North Carolina State University

Experiences-Professor, Department of Tropical Plant and Soil Sciences,
University of Hawaii at Manoa-Computer applications in Soil and Agricultural Science –Phosphorus Decision Support System(PDSS), Nutrient Managementin Agricultural Systems (NuMaSS),-Water conservation & harvesting – West Africa-Teaches courses in Soil-Plant-Nutrient Interactions, Geospatial
Analysis of Natural Resource Data
-Fulbright Scholar – Mozambique 2009ISBN 978-616-90047-7-6