Chapter 7 Effective ways to use compost

7.

Effective ways to use compost

7.1

Effects of compost

The basic concept of composting may be expressed as “converting organic substances into a form thatenables uses by plants through decomposition and re-synthesis or to a form that enables use as a soil
improvement material that enhances the ease of aggregation of soil particles and the air-permeability,
realized by the workings of microorganisms and soil animals*.”
In view of the above, the compost effects may be expressed as “supplying fertilizing components (nitrogen,phosphate, potassium, calcium, magnesium, etc.) necessary for plant growth” and “soil improvement andmaintenance of the improved conditions.” Of the above, supplying of fertilizing components is possible bychemical fertilizers also. On the other hand, the soil improvement effect and maintenance of the improved
conditions is an effect brought about by composting only. It is not exaggerating to state that “use ofcompost is the solution for dealing with (resolving) soil fatigue, which has been a problem all over theworld.”* Soil animals is a generic term referring to animals living in soil, ranging from ameba, nematode,
earthworms, mites, collembolan, ants to moles and various other groups of animals. There arepredators and decomposing animals, of which the latter enrich the soil by decomposing fallen leaves,branches and other plant matters and dead bodies of animals. However, the soil animals mentioned
here do not include moles or other mammals. The methods of composting using soil animals that are
already in a practical application stage include those using earthworms, larvae of house fly, andlarvae of soldier fly.
7.1.1

Relationship between the amount of application of fertilizing components and the yield

Compost is being used in farming, and the greatest point of interest is on “enhancing the yield of crops.”
Here, the “relationship between the applied amount of fertilizing components and the yield of crops” isexplained.
The diagram shows the relationship between the applied amount of fertilizing components and the yield ofcrops for four methods of plant cultivation, namely the “[1] conventional cultivation,” “[2] fertilizer
application improvement,” “[3] soil improvement and fertilizer application improvement,” and “[4]comprehensive improvement.” The yield of crops showed the tendency to increase when the appliedamount of fertilizing components increased, with all of the methods. Here, the applied amount of fertilizing
components shown in the diagram refers to fertilizing (nutrient) components that are absorbed by farm
products, contained in both chemical fertilizers and compost.

1© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Relationship between the applied amount of
fertilizers and the yield of crops
Small  Yield of crops  Large

Direction toward greater yield[4] Comprehensive improvement[3] Soil improvement and fertilizer
application improvement[2] Fertilizer application improvement[1] Conventional cultivation

Small  Applied amount of fertilizer  Large

Fig. 7-1: Relationship between applied amount of fertilizing components and yield of crops
7.1.2[1] Conventional cultivation

Farmers determine the amount of fertilizer applied based on
their experiences and intuition. To begin with, the optimum
fertilizer demand and climatic conditions differ by the types
of farm products. If unable to meet the demand on each of thecomponents, the yield would be limited because of the mostdeficient component. In the diagram, the height of the barrel
represents the component amount and conditions necessary
for farm products, and the amount of water represents theinherently obtainable yield. In the diagram, the yield has

Fig. 7-2: Fertilizer application and yield indecreased as represented by the water flowing out of thethe conventional cultivation methodbarrel, because of the deficiency in the phosphate (P) amount.
The deficiency of necessary fertilizing components is a phenomenon observed with both chemicalfertilizers and compost.

2© 2019 Koji TakakuraChapter 7 Effective ways to use compost

7.1.3[2] Fertilizer application improvement

The amount of fertilizer applied is determined byclarifying the fertilizer components contained in the soil,
and in a way suited to the fertilizer demand of each farm
product. This is a cultivation technique based on the socalled fertilizer application design, in which well-balanced
fertilizer application management is attempted. Phosphate
was deficient in the example shown for the conventional
cultivation, so phosphate was added through the fertilizer
application improvement and the yield has increased. As
shown in the diagram, it would be possible to obtain theyield inherently obtainable from the soil. However, there isFig. 7-3: Fertilizer application and yield in thefertilizer application improvement method

a limit to the obtainable yield, and soil improvement isalso necessary for increasing the yield further.
7.1.4[3] Soil improvement and fertilizer application improvement

Fertilizer application design prevents deficiency in the fertilizing components necessary for a farm product,but does not consider the conditions of the soil, which is the base for the growth of plants. Good-quality
soil needs to be prepared for enhancing the yield further, in order to bring out the capacities inherent to theplants to the utmost.

Physical properties
Soil softness, water
permeability, water
retention capacity, airpermeability, etc.

Chemical properties
Nitrogen, phosphate,potassium, pH,
minerals, etc.

The situation in which
the necessary conditions are
met with regard to the threeareas of properties

Biological properties
Life forms livingin the soil

Fig. 7-4: Fertilizer application and yield in the soil improvement andfertilizer application improvement method
7.1.5 [4] Comprehensive improvement
Introduction of improved breeds and comprehensive improvement that involves cultivation techniques arealso necessary for enhancing the yield further. The diagram represents an example that implements breed
improvement, soil improvement and fertilizer application improvement.

3© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Physical properties
Soil softness, water
permeability, water
retention capacity, airpermeability, etc.

The situation in which
the necessary conditions are
met with regard to the three
Nitrogen, phosphate,areas of properties
potassium, pH,
minerals, etc.
Chemicalproperties

Biological properties
Life forms livingin the soil

Fig. 7-5: Fertilizer application and yield in the comprehensive improvement method
7.1.6

Excessive fertilizer application leads to decline in yields

There would be no problem if appropriate amounts of fertilizers were applied based on the fertilizer
application design. However, excessive fertilizer application could result from an error in calculation or afalse belief based on the desire to enhance the yield. In such cases, the yield would decline in all of thecultivation methods. Under the circumstances, a symptom sometimes arises that indicates deficiency ofanother fertilizing component even when the component is actually sufficient, due to the influence of theexcessive component.

Relationship between the applied amount of
fertilizers and the yield of crops

Small  Yield of crops  Large

Direction toward greater yield[4] Comprehensive
improvement[3] Soil improvement and fertilizer
application improvement[2] Fertilizer
application
improvement[1] Conventional
cultivation[5] The yield declines if fertilizer
was applied excessively
Small  Applied amount of fertilizer  Large

Fig. 7-6: Excessive fertilizer application leads to decline in yield

4© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Let us consider a case of excessive application of nitrogen (NH4-N: ammonia nitrogen), when actually allof the fertilizing components have been applied sufficiently. A molecule of NH4-N is of a size almost thesame with potassium, and farm products have an illusion that they have absorbed potassium instead when
there is excessive NH4-N. As a result, the farm products
show a symptom of potassium deficiency. As acountermeasure, additional potassium would be applied
if judged from the symptom only, causing potassium to
be excessive. Excessive potassium hinders absorptionof magnesium, resulting in magnesium deficiency.
Additional magnesium would be applied as acountermeasure, leading to excessive magnesium.
Excessive application of fertilizing components inducesa chain reaction that destroys the soundness of the soil.
Since the above is a case of excessive application ofFig. 7-7: Excessive fertilizer application

fertilizing components, the soundness of the soil would

and yield

be destroyed regardless of whether a chemical fertilizer
or compost was applied.
7.1.7

Characteristics of chemical fertilizers and compost

The characteristics of chemical fertilizers and compost are outlined below.
(1) Chemical fertilizers:•

Application is easy, and effects appear quickly•

Targeted fertilizer components may be applied (fertilizer application design is easy)•

Causes deprivation of the number and species of microorganisms•

Causes decline in the number of organic substances in soil•

Causes acidification of soil

Soil fatigue(Collapse of soil aggregates)(2) Compost:•

Amounts of fertilizer components are small and application is burdensome•

Diverse fertilizing components may be applied•

Increases the number of organic substances in the soil

Soil improvement and•Diversifies the species of microorganisms and other life forms

maintenance of improved•

Promotes aggregation of soil particles•

Enhances the soil cushioning effectconditions

5© 2019 Koji TakakuraChapter 7 Effective ways to use compost

7.1.7

Purposes when attempting composting

Let us reconfirm the purposes we have in mind when attempting composting.
From a viewpoint of the environment, the primary purpose would be to recycle discarded organic
substances in raw garbage and other wastes into compost. This is the so-called volume reduction andrecycling of organic wastes, as a part of the efforts for improving waste management.
However, targeting only at improvement of waste management is not sufficient, and a viewpoint of using
the produced compost effectively is also necessary along with the improvement in waste management. The
efforts would be meaningless unless compost products were used effectively for plant cultivation. Here,easy ways of thinking should be avoided. For instance, compost products are not to be used as covering soilat landfill disposal sites when only low-quality compost has been produced that does not fulfill the market
demands, or when market distribution is not possible because surveys on demands on compost products
have not been conducted properly. This is because the capacity for plant cultivation inherent to compost is
not being utilized effectively in such cases, even though contribution has been made to reduce the volumeof landfilled wastes.
As discussed above, the following four items are necessary for enhancing the yield of farm products.

i.

Fertilizer application designii.

Soil improvementiii. Breed improvement
iv. Scientific cultivation management
When cultivating farm products using soil, the soil needs to be in a sound condition. In other words, soil
improvement and maintenance of the improved conditions hold the key for enhancing the yield and also forsustainable agriculture.
The purpose when attempting composting may be summarized as “contributing toward the enhancement ofyields and sustainable agriculture by using produced compost, at the same time improving waste
management through volume reduction and recycling of organic wastes.”
7.2

Soil improvement

The essential elements needed for plant growth are the “light,” “appropriate temperatures,” “water,” “CO2(photosynthesis),” “O2 (on the ground and around roots),” and “nutrient components (fertilizing
components),” among which the soil is not included. Solution culture, for example, enables plants to be
cultivated without soil. However, facility introduction and nutrient solution management are necessary, and
it is not practical to conduct solution culture on an extensive area. Cultivation using the soil is the mostappropriate for cultivating farm products over a vast area for feeding the global population, utilizing thepower of nature to the utmost.

6© 2019 Koji TakakuraChapter 7 Effective ways to use compost

For sustainable agriculture that enables farm products to be produced efficiently and stably, soil
improvement and maintenance of the improved conditions would be necessary. The soil improvementmeans improving the conditions of the soil. What, then, are the desirable conditions for the soil? One might
imagine “the soil in which a lot of earthworms live,” “soft, fluffy soil,” “healthy soil,” and “soil with highproductivity.”
Here, soil improvement is considered from a viewpoint of improving the three elements of soil, namely the“physical properties, chemical properties and biological properties.”
7.2.1

Improvement of physical properties

The physical properties of soil mainly refer to the “water permeability (ease of drainage),” “airpermeability (air passage),” and “water retention property (water holding property).” Let us think over theprocess in which the physical properties are improved, as the soil conditions change when compost is used.
(1) Constituent elements of soil
The soil comprises inorganic substances and organic substances, and many of the inorganic substances arederived from minerals. Of the inorganic substances in the soil, those with particle diameters of 2 mm or
greater are referred to as “gravels,” and the portion excluding the gravel is referred to as “fine soil.” Thefine soil contains inorganic substances of diverse sizes, and those with particle diameters between 0.2 and
2.0 mm are referred to as the “coarse sand,” those between 0.02 and 0.2 mm as the “fine sand,” thosebetween 0.002 and 0.02 mm as the “silt,” and those smaller than 0.002 mm as the “clay.” The soil contains
about several percent to 10% of organic substances in many cases, such as bodies of dead animals andplants, life forms in the soil (microorganisms and soil animals), and matters discharged by the life forms inthe soil. The soil in farmland may be represented as the diagram below.

Constituent elements of soil

Clay

Sand

Organic
substances

Life forms in the soil

(microorganisms and soil animals)

Fig. 7-8: Constituent elements of soil

7

© 2019 Koji TakakuraChapter 7 Effective ways to use compost(2) Aggregation of soil particles
Clay particles are extremely small particles measuring less than 0.02 mm. The particle size increases a little
when the particles form a bond with hydrous oxides of iron, magnesium, manganese and other metals. The
clay particles form a bond with cells of bacteria, humus formed when dead bodies of animals and plants
stabilize in the soil, and plant fragments using a viscous substance discharged by microorganisms, resulting
in formation of small aggregates. These are called microaggregates. The viscous substance is similar to“natto,” a fermented food product of Japan. Let us now look at the process of formation of soil aggregates.

8© 2019 Koji TakakuraChapter 7 Effective ways to use compost

How is a soil aggregate formed?
Organic substances

Microorganisms

Microorganisms eat organic
substances in the soil and discharges viscous substances
Hydrous oxides of iron,aluminum, etc.

Clay particles stick with each otherFig. 7-9: Improvement of physical properties starts with bonding of clay particles with hydrates of metals

A clay particle is an extremely small particle measuring less than 0.002 mm (2 μm), and gets tangled withthe viscous substance discharged as metabolites of soil animals, as well as fragments of dead plant bodies.
The tangled substance grows in the size gradually, forming a small aggregate measuring less than 0.25 mm(250 μm). This is called a microaggregate.

Increasing further in the aggregate size

Organic substances
Plant
fragments

Microaggregates
MicroaggregatesFig. 7-10: Metabolites of soil animals cause microaggregate to be formed

9© 2019 Koji TakakuraChapter 7 Effective ways to use compost
Furthermore, fungal threads of molds (filamentous bacteria) cause microaggregates to get tangled withfragments of dead plant bodies and plant roots, thus forming larger aggregates named macroaggregates. A
macroaggregates measures 0.25 mm (250 μm) or larger, some of them measuring more than 1 mm.

Microaggregates stick with each other

Sand
Remnant
roots

Organic
substances

Soil animals

Mold

Macroaggregate

Fig. 7-11: Aggregation is completed with macroaggregates

The aggregates are shown in a ball form in the diagram for making the process easier to understand. In
reality, however, aggregates have distorted forms because they are tangled with plant roots and fungal
threads. The photograph below is an example of macroaggregates tangled with plant roots.

Photograph 7-1: Macroaggregates formed around plant roots10© 2019 Koji TakakuraChapter 7 Effective ways to use compost(3) Soil in which macroaggregates have formed
The physical properties of soil, namely the “water permeability (ease of drainage),” “air permeability (airpassage)” and “water retention (holding) property,” improve if macroaggregates were formed. The
following diagram shows the situations of clay soil, sandy soil and soil with macroaggregates.

The soil feels soft and fluffy!
Clay

Sand

Soil with aggregates

Air

Air

Water permeability
Air permeability
Water retention
property

Fig. 7-12: Merits from physical properties improvement
Why do macroaggregates bring about improvement in the three elements of properties? It is because
macroaggregates contain microaggregates within. The soil composed only of small particles like clay
hinders “water permeability” and “air permeability.” On the other hand, the soil composed only of large
particles like sand hinders “water retention property.”
As can be seen in the enlarged view of the soil with macroaggregates, the “water permeability” and “airpermeability” are secured by gaps between macroaggregates, while the “water retention property” issecured in small gaps between microaggregates that constitute a macroaggregate, through the capillary
phenomenon. Letting the water pass through and the air pass through, which are seemingly contradictory
phenomena, are taking place at the same time. This may indeed be described as the power and gift of thenature.

11© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Effects of macroaggregates
Outside ofmacroaggregates
High air permeability
High water permeability

Inside of macroaggregates
Capillary water is retained
Fertilizing components
have dissolved in the water

Fig. 7-13: Improvement of physical properties by macroaggregates(4) Relationship between air permeability and water permeability
Plant cultivation always involves “watering (inundation),” so it should not be difficult to link water
retention with plant cultivation. It is often said that “plant roots decay” when the water is not drained well,so akadama soil with large particles is often placed in a pot when cultivating a plant in the pot, forpromoting drainage. On the other hand, plant roots are immersed completely in the nourishing solution
when the plants are grown by solution culture. In solution culture, measures are always provided forsupplying oxygen to the plant, through aeration and other means, so the roots in the nourishing solution
would not suffer from oxygen deficiency. This is because growth of the plant would be hindered
tremendously if the plant roots are not growing or functioning soundly.

Air pump

Fig. 7-14: Oxygen is supplied by aeration in solution culture12© 2019 Koji TakakuraChapter 7 Effective ways to use compost
Although a sufficient amount of oxygen needs to be supplied for keeping the plant roots active andpromoting their sound growth, the oxygen concentration (dissolved oxygen in case of a solution) needs not
be in the order of percent. In case of solution culture, the saturated dissolved oxygen concentration at thewater temperature of 20°C is about 9 ppm (0.0009%). For many crops, the respiration speed declines
rapidly and the plant growth is affected significantly when the dissolved oxygen concentration falls below
1.5 to 2.0 ppm.
The same applies when plants are cultivated on a farmland. Only about 0.0009% of oxygen is foundunderwater, while the oxygen concentration in the air is about 21%. If there are many gaps in the soil, even
if the gaps were small, the air penetrates into the gaps and enables plant roots to breathe sufficiently andremain active. In other words, a farmland would be improved to one that facilitates breathing by plants, asaggregation of the soil progresses.
On the other hand, rain and inundated water fill the gaps between aggregates. The water permeates
underground slowly when the soil is well drained. In the process, the air penetrates into the gaps in the soil,
as if the air is pulled in by the water that is permeating underground. This means that the air in the gaps
among soil aggregates is replaced each time the rain falls or the soil is inundated.

Rain and inundated waterAir

Fig. 7-15: The air penetrates into the soil when the water is drained

However, rice cultivation in rice paddies is an exception. Even though rice is cultivated in water, rice plant
has a body part that sends the oxygen taken in above the ground efficiently to the roots. Therefore, the roots
rarely decay due to deficiency of oxygen. However, rice plant grows better when the amount of oxygen
supplied to the root increases. As such, a rice cultivation method has disseminated in which the rice paddies
are drained repeatedly for supplying the oxygen to the plant roots.

13© 2019 Koji TakakuraChapter 7 Effective ways to use compost(5) Promoting soil aggregation
Soil aggregates are formed through complicated reactions among diverse elements. In this section, thephenomenon was described in a simplified way for making the process easier to understand, with emphasis
placed on the discharge of viscous substance from activities of microorganisms and the fungal threads ofmolds and plant roots that play crucial roles in formation of soil aggregates. Compost application is aneffective way to increase the viscous substance and fungal threads of molds. This is because compost is anaggregate of microorganisms and organic substances. Microorganisms in compost decompose organic
substances in the compost and discharge the viscous substance and extend the fungal threads of mold. In
this regard, compost with a larger amount of remnant organic substances that may be used by
microorganisms would be more advantageous in terms of soil aggregation. In other words, application of
the half-matured compost is effective from a viewpoint of soil aggregation. On the other hand,decomposition of organic substances has been terminated beforehand with the fully matured compost, inorder to suppress damages caused by activities of microorganisms after the compost is applied as a fertilizer.
If soil aggregates were formed when compost is used, do the aggregates remain forever? Since compost
application is burdensome, it is natural for farmers to want to switch to chemical fertilizers after soil
aggregates have been formed. However, chemical fertilizers alone cannot maintain the soil aggregates. If
only chemical fertilizers were applied, organic substances in the soil are used by microorganisms andgradually decrease. Since the viscous substance is an organic substance and the fungal threads of molds arealso organic substances after the molds have died, they are decomposed and used by microorganisms in thesoil, causing the soil aggregates to collapse. The phenomenon has taken place at many farmlands, where thesoil has hardened.
Then, where could the soil with the highest degree of soil aggregation (where the soil aggregates are in thebest condition) be found? Could it be the soil of a well-managed farmland where compost is applied
continuously? Telling the truth, soil aggregation has advanced the most in grasslands. Plants send a third oforganic components they have produced through photosynthesis to the soil, and store them by formingroots and underground stems or discharging them as Mucigel from the roots. Microorganisms in the soil
can stay active by using dead bodies of plants, remnant roots and Mucigel, enabling them to promote andmaintain soil aggregation. In grasslands, organic substances continue circulating without being taken out asvegetables or other crops. At farmlands, crops are taken out and excessive oxygen is supplied to the soil
through tillage that promotes decomposition of organic substances. As a result, the balance observed ingrasslands is destroyed.
In grasslands, woods, forests and other natural regions, the nature has prepared by itself the soil conditions
necessary for natural plant growth. On the other hand, farmlands have been developed artificially forcultivating farm products. Compost application and other artificial means are needed for maintaining the
farmlands fit for farm product cultivation. Improved breeds that offer larger crops have been introduced forfarming in order to increase the food production. Unless appropriate cultivation techniques are also
introduced, farmlands would only continue becoming exhausted.

14© 2019 Koji TakakuraChapter 7 Effective ways to use compost
7.2.2

Improvement of chemical properties

Chemical properties of soil mainly refer to the “fertilizing components,” “fertilizer holding property/ cationexchange capacity (CEC),” “pH,” and “electric conductivity (EC).” Let us consider how the “fertilizing
components,” “fertilizer holding property/ cation exchange capacity (CEC)” and other chemical propertiesof the soil improve by using compost.
(1) Improvement of fertilizing components[1] Fertilizing components necessary for plant growth
One of the primitive ways of clearing a land for cultivation is slash-and-burn farming. The place of slashand-burn farming is shifted because the growth of crops slows down when they are cultivated repeatedly at
the same location. However, unorderly repetition of slash-and-burn farming significantly damages theforest environment.
Why, then, does the growth of vegetable crops slow down?
The answer is simple. In the natural environment, plants grow by absorbing nutrients from the soil throughtheir roots. When leaves fall or plants wither, they are accumulated on the soil. The accumulated substances
are returned to the soil by being decomposed by microorganisms and soil animals, and will be used again as
nutrients of new plants. On the other hand, crops are being cultivated to be harvested. This means thatnutrients in the soil are brought outside by being absorbed by the crops. The nutrients in the soil decreaseeach time crops are cultivated. Therefore, fertilizing components need to be supplied artificially in someways, for continue cultivating crops.
The fertilizing components necessary for plant growth are broadly categorized into the “main elements,”“auxiliary elements” and “microelements.”i

Main elements
There are three main elements, namely nitrogen (N), phosphorus (P) and potassium (K).

ii•

Nitrogen (N): promotes growth of leaves and stems and makes the plant body larger.

•

Phosphorus (P): promotes growth, shooting, blooming and fruition.

•

Potassium (K): makes roots and stems stronger and promotes blooming and fruition.

Auxiliary elements
There are three auxiliary elements, namely calcium (Ca), magnesium (MG) and sulphur (S).
• Calcium (Ca): reinforces cell tissues and makes the plant body stronger.
• Magnesium (Mg): helps absorption of phosphates and is a component for forming chlorophyll.
• Sulphur (S): is involved indirectly with protein synthesis and chlorophyll formation.

15© 2019 Koji TakakuraChapter 7 Effective ways to use compostiii

Microelements
There are eight microelements, namely iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo),manganese (Mn), boron (B), chlorine (Cl), and nickel (Ni).
•Iron (Fe): is a component for forming oxygen involved in photosynthesis reaction.

•

Copper (Cu): is involved in photosynthesis and respiration.

•

Zinc (Zn): adjusts the plant growth hormone and is involved in cell division.

•

Molybdenum (Mo): is a component of nitrate reductase and is involved in protein anabolism of
nitrate nitrogen.

•

Manganese (Mn): is a physiologically important component involved in formation ofphotosynthesis enzyme and chlorophyll.

•

Boron (B): is involved in formation and maintenance of cell membrane and growth of roots andsprouts.

•

Chlorine (Cl): is involved in photosynthesis along with manganese.

•

Nickel (Ni): is a component of urease.

In addition, silicon (Si) is also worthy of attention. Plants absorb this element in a form of silicon oxide(SiO2), which is effective in hardening the outer skin and preventing intrusion by pathogenic bacteria.
Plants of Gramineae absorb a large amount of silicon oxide, and attention needs to be given on siliconoxide supply, especially when cultivating rice.
[2] Fertilizing components that require attention when applied to the soil for crop cultivation
The fertilizing components essential for plant growth are as discussed above. Among these are components
with especially low concentration in the soil. The concentration in the soil varies by regions, because it has
been evaluated based on the mean value of the analysis results obtained at various places of the world.
However, the data are informative when considering the supplies of fertilizing components.
The nutrient components necessary for crop cultivation that tend to become deficient unless supplied to thefarming soil in one way or another are listed below, in the order of the tendency to become deficient:N≫P > B > S > Cl > K > Zn >Mg > Ca
All of the three main elements, nitrogen, phosphorus and potassium, tend to become deficient. It tells why
the chemical fertilizers being applied often predominantly consist of these three components. Put in anotherway, crops may be cultivated by applying chemical fertilizers comprising nitrogen, phosphorus andpotassium, for the time being. As time goes by, however, other components would be absorbed by the crops
and taken out of the soil, raising the risk of deficiency, especially with boron, sulphur, chlorine and zinc.

16© 2019 Koji TakakuraChapter 7 Effective ways to use compost[3] Supplying fertilizing components by using compost
Manufactured chemical fertilizers do not contain any component other than those intended. As such, if only
chemical fertilizers were used continuously, other necessary fertilizing components become deficient, andusers realize the deficiency of fertilizing components for the first time when the symptoms appear. Some
users fail to understand that the observed symptoms are those of deficiency of fertilizing components andmisunderstand them as damages caused by pathogens and harmful insects, and could take erroneous
measures such as sprinkling agrichemicals.
If compost was made from vegetables and other plant-derived materials or cattle manure or feces of otherlivestock that feed on plants, the source materials contain the “main elements,” “auxiliary elements” and“microelements,” and the produced compost would also contain them. In other words, deficiency offertilizing components may be prevented by using the compost.
This is what it means by the improvement of fertilizing components.
(2) Fertilizer holding property/cation exchange capacity (CEC)[1] Holding the fertilizing components
The capacity of the soil to adsorb fertilizing components is referred to as the “fertilizer holding property,”and is generally represented as the cation exchange capacity (CEC), which is the same as the capacity toadsorb positive ions of fertilizing components. Since a positive ion is also represented as a “base,”sometimes the capacity is also referred to as the base exchange capacity. Many of the fertilizing
components dissolved in water in a form of ions are cations, the typical examples including an ammonium
ion (NH+), a calcium ion (Ca2+), a magnesium ion (Mg2+) and a potassium ion (K+). On the other hand, anitrate ion (NO3-) is an anion.
When the cation exchange capacity of soil is small, many of the fertilizing components are washed away
and become lost at a time of rainfall or sprinkling of water. When it is large, a greater amount of fertilizing
components is adsorbed, preventing the fertilizer components from becoming washed away and lost fromthe soil. As a result, the fertilizing effect would last longer. However, anions like nitrate ions (NO3-) get
washed away and become lost more easily, without being absorbed by the soil.

17© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Rainfall andwater sprinkling

Soil

Soil

Many fertilizing
components are
washed away andbecome lost

Soil withsmall CEC

Rainfall andwater sprinkling

Soil

CEC withlarge CEC

Soil

Only a few fertilizing
components are
washed away andbecome lostFig. 7-16: Mechanism of cation exchange capacity (CEC)The CEC of clay minerals in the soil tends to be large, even though the level differs by the type of clay
minerals. The CEC also relates to the amount of humus. Organic substances in soil are decomposed bydiverse soil animals, and become stabilized as “humus” at the end that is difficult to decompose. The
humus is involved closely with soil aggregation also.
By applying compost continuously as a fertilizer, the amount of humus in the soil increases and soil
aggregation is also promoted, causing the CEC of the soil to rise.
[2] Mitigation of fluctuation of pH of the soil

The pH value of soil of a farmland tends to decline when crops are cultivated in the soil. Since therange of pH values between 6.0 and 6.5 is optimum for the majority of crops, growth of the crops ishindered in many cases if cultivated in acidic soil of a pH value below the range. The mechanism ofnutrient absorption by plant roots is that when the roots absorb nutrients of a form of cations, the roots18© 2019 Koji TakakuraChapter 7 Effective ways to use compost
discharge hydrogen ions (H+), which are also cations. For this reason, the pH value declines in a
microscopic portion of the roots. However, if the CEC of the soil was large, rapid change in the pH value ofthe soil would be mitigated.

Discharged

Discharged

Absorbed

Absorbed

Discharged

Soil

Discharged

Absorbed

Absorbed

K+ held in the soil is absorbed by the roots in
exchange with H+ discharged from the roots,
and thereby the pH does not change.

Free K+ in the soil are exchanged with H+
discharged from the roots, making the H+ freeand lowering the pH of the soil.

Fig. 7-17: Change in pH of soil
[3] pH of soil and absorption of fertilizing components
The optimum range of pH values in thesoil is between 6.0 and 6.5 for the
majority of plants, as discussed above.

Nitrogen (N)The range may also be described as a

Phosphorus (P)desirable range of pH values for plants

Potassium (K)when using fertilizing components in

Sulphur (S)Calcium (Ca)the soil. The diagram shows theMagnesium (Mg)relationship between the pH values ofIron (Fe)soil and the level of dissolution andManganese (Mn)usage of fertilizing components. The
diagram

shows

that

the

Boron (B)thirteen

Copper (Cu) and Zinc (Zn)
Molybdenum (Mo)essential elements (the main elements,
auxiliary elements and microelements),

Fig. 7-18: pH of soil and absorption of fertilizing components

which are indispensable for growth ofplants, may be used in the just right quantities when the pH values are in the range between 5.5 and 7.0.
The proper pH values for most vegetables are within the range, but some vegetables could suffer damage
from absorption of excessive manganese when the pH is about 5.5. Therefore, to be on the safe side, theoptimum range of pH values should be between 6.0 and 6.5.

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© 2019 Koji TakakuraChapter 7 Effective ways to use compost
4.2.3

Improvement of biological properties

The biological properties of soil mainly relate to “soil animals” and “soil microorganisms.” When diverse
species of life forms (diverse life forms) live in a soil in a well-balanced way, the soil may be described as a“lively soil.” Improvement of biological properties aims at preparing the “lively soil.”(1) Soil animals
The term soil animals might sound unfamiliar. They refer to animals that spend most of the time in the soil(including underneath fallen leaves). By applying compost continuously to a farmland, a large number ofdiverse species of soil animals come to inhabit the soil. These animals play important roles in preparationof high-quality farmland soil. They are classified in various ways, but the simple way is to classify themaccording to the sizes. Please note that moles, lizards, snakes, and the like that are classified as large soil
animals are not considered because the discussions here are made from a viewpoint of soil improvement.
Table 7-1: Species of Soil Animals

Classification

Body length

Species

Microfauna(small soil animals)

Less than
0.2 mmMastigote, ameba, ciliate, rotifer, etc.

Mesofauna (mediumsized soil animals)

0.2 to 2 mm

Nematode, Enchytraeus buchholzi, mite, false scorpion,collembolan, thrips, symphyla, etc.

Macrofauna(large soil animals)

2 to 20 mm

Earthworm, wood louse, sow bug, ant, larvae of beetles,
larvae of flies and horseflies, Campodeoidea, centipede, etc.

The photographs of soil animals I have collected on farmlands are shown below as examples. The
photographs were taken under a stereoscopic microscope at magnification ratios of about 20 to 40.

Photograph 7-1: Mite

Photograph 7-2: Mite

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Photograph 7-3: Mites© 2019 Koji TakakuraChapter 7 Effective ways to use compost

Photograph 7-4: Mite

Photograph 7-5: Mites

Photograph 7-6: Mites

Photograph 7-7: Mite

Photograph 7-8: Mite

Photograph 7-9: Mite

Photograph 7-10: Collembolan

Photograph 7-11: Collembolan

Photograph 7-12: Collembolan

Photograph 7-13:
Alaska bellheather

Photograph 7-14:
Stone centipedes

Photograph 7-15: Nematode

Photograph 7-16: Campodeoidea

Photograph 7-17:
Enchytraeus buchholzi

Photograph 7-18: Wood louse21© 2019 Koji TakakuraChapter 7 Effective ways to use compost
The roles played by soil animals may be roughly classified into the following three categories.
i.

Eating and decomposing dead plant bodies: hard and dry dead plant bodies are eaten and crushed bysow bugs, wood lice, moss mites, large earthworms and other life forms.

ii.

Promoting soil aggregation: feces discharged by animals that ate dead plant bodies as in item i above
are a part of soil aggregates, and crushed dead plant bodies promote soil aggregation as they aredecomposed and digested by collembolans, millipedes, snails, earthworms, Enchytraeus buchholzi,
Nematoda and other life forms.

iii. Maintaining diversity of soil animals: uneven proliferation of certain species of soil animals is
suppressed when diverse soil animals inhabit the soil. This leads to prevention of abnormal outbreakof harmful insects.
There are also other soil animals that perform important roles. A typical example is a tillage effect brought
about by earthworms. Earthworms swallow soil microorganisms and organic substances, and defecate
above ground through the intestinal tract. There is a report that on grassland and other grounds fit for
growth of earthworms, the volume of tillage by earthworms is estimated to be 50 ton/hectare. Also, tunnels
formed when earthworms pass in the soil help raise the void ratio. On the other hand, the species of mites
include not only those regarded as agricultural pest, but also one that preys on these species of mites andused as a biological agrichemical. Also, among the species of collembolans is one that likes to eat
pathogenic molds.
(2) Soil microorganisms
Growth only of a specific soil microorganism may be suppressed if diversity of microorganisms in the soil
is enhanced. This enables prevention of the spreading of diseases among farm products. A cultivation
method in which farmland soil is disinfected is sometimes adopted. If so, a close attention needs to be paid
for preventing intrusion by pathogenic bacteria. A disease could spread instantaneously if there is almost no
microorganism that can compare favorably with the pathogenic microorganisms, while the farmland soil
contains plenty of nutrient components (organic and inorganic substances) necessary for growth of
microorganisms.
Among microorganisms, there is a species of actinomycetes that produces antibiotics. A compost productmade using the species of actinomycetes has been produced and sold for preventing spreading of fungi ofgenus fusarium. There are also microorganisms that produce hormone-like substances, vitamins and aminoacids that help crops to grow. On the other hand, there is also an opinion that the vitamins and amino acids
are not likely to help plants grow, and the author intends to discuss the matter briefly.
i.

Vitamins and amino acids necessary for the growth of microorganisms
Humans obtain vitamins and amino acids necessary for their biological activities that they cannot
produce in their bodies from foods. Similarly, some soil microorganisms do not have a metabolic
system for configuring all of the elements necessary for their growth (vitamins, amino acids andothers), and they seek the deficient nutrient elements outside. This is referred to as auxotrophy. In
22© 2019 Koji TakakuraChapter 7 Effective ways to use compost
other words, when auxotrophic microorganisms multiply by using vitamins and amino acids producedby other microorganisms, the biological diversity of the soil is enhanced and this would help farm
products grow.
ii.

Amino acids absorbed by plants

The Liebig’s law of the minimum has been recognized as a universal principle regarding theabsorption of nutrient elements by plants from the roots for their growth, which may be summarized
as follows.
“When an organic fertilizer, including compost, is applied on the soil, the organic substances aredecomposed by soil microorganisms and discharged into the soil as nitrate ions (NO3-), ammonium
ions (NH4+), phosphate ions (PO43+) and other inorganic ions. The inorganic ions are absorbed as
nutrients from plants’ roots. In other words, plants use organic substances that have been converted toinorganic ions by microorganisms, instead of directly absorbing the organic substances as nutrient
components.”
On the other hand, the effectiveness of the direct absorption of amino acids by plants’ roots has been
confirmed.
“Some plants showed growth relying only on amino acids as a source of nitrogen.”“The raw materials of amino acids synthesized in plant bodies are usually carbohydrates produced byphotosynthesis and inorganic nitrogen absorbed from the roots. On the other hand, if amino acids wereabsorbed directly from the roots, the plant may skip the process for synthesizing the amino acids in its
body. Therefore, direct absorption of amino acids from the roots is believed to be more advantageous
for the growth of plants compared to the use of inorganic nitrogen.”“If easily metabolized amino acids were absorbed directly by the roots of a plant when the plant
growth is being regulated by the speed of photosynthesis under unstable weather conditions, the aminoacids would be used as is for the growth of the roots. The root activity is enhanced at the same time,
which is believed to increase the amount of nutrients supplied to the portion of the plant above theground and thus promoting the growth of the portion above the ground.”Direct absorption by roots of organic polymers such as red blood cells has also been observed.

23© 2019 Koji TakakuraChapter 7 Effective ways to use compost
References:•

Koji Takakura: Kaigai Gijutsu Kyoryoku wo Tsuujita Takakura-shiki Konposuto no Gijutsu Iten ni
Kansuru Kenkyu (A Study on Technical Transfer for Takakura Composting Method through Overseas
Technological Cooperation), doctoral thesis, Graduate School of Life Science and Systems
Engineering, Kyushu Institute of Technology, May 2016•

Daisuke Koma, Hayato Yamanaka, Kunihiko Moriyoshi, Takashi Omoto: Baichi no Seibun
Shittemasuka? (Are you familiar with the components in the culture medium?), Journal of Bioscienceand Bioengineering, Vol. 89, No.4, pp.195-199, April 25, 2011•

National Institute for Agro-Environmental Sciences: Riibihhi no Muki Eiyo Setsu to Dojo Hiryo Gaku
(The Liebig’s law of the minimum and science of soil and fertilizers), Nogyo to Kankyo (Agriculture
and the Environment), No. 102 (October 1, 2008)•

Naoto Nihei: Shokubutsu no Amino-san Kyushu – Shokubutsu no Shurui, Amino-san no Shurui ni Yoru
Chigai (Amino acid absorption by plants – the differences by the plant species and type of aminoacids), Nogyo Gijutsu Taikei Dojo Sehi-hen, Sakumotsu Eiyo III (Encyclopedia of agricultural
technologies, section for soil and plant nutrition, volume for crop nutrition III), Rural Culture
Association Japan, pp.44-10 to 17, 2009•

Ippan Shadan Hojin Zenkoku Hiryo-sho Rengokai (Federation of Nationwide Fertilizer Dealers): Sehi
no Shin Chishiki (New Findings on Fertilizer Application), Rural Culture Association Japan•

Tetsuro Kato: Dojo Hiryo no Kihon to Tsukurikata Tsukaikata (The Basics of Soil and Fertilizers and
How to Prepare and Use Them), Natsumesha Co., Ltd.

•

Michinori Nishio: Dojo Biseibtsu no Kiso Chisiki (Basic Knowledge on Soil Microorganisms), Rural
Culture Association Japan•

Shingo Iwata, Akemi Tsukamoto: Dare Demo Dekiru Yasashii Tsuhi-no Shirabekata (How to Examine
Soil, Made Easy for Everyone), Godo Shuppan (publishing company)•

Shingo Matsumoto, Kyoji Ako: Sakumotsu wa Naze Yukibutsu Nanyokai Seibun wo Kyushu
Dekirunoka (How Crops Absorb Organic Substances and Hardly Soluble Components), Rural Culture
Association Japan•

Shunrokuro Fujiwara, Tetsuro Anzai, Tetsuro Kato: Dojo Shindan no Hoho to Katsuyo (Methods andApplication of Soil Diagnosis), Rural Culture Association Japan•

Ichiro Yamane: Tsuchi to Biseibutsu to Hiryo no Hataraki (Functions of Soil, Microorganisms andFertilizers), Rural Culture Association Japan•

Shingo Iwata: Kenko na Tsuchi, Yanda Tsuchi (Healthy Soil, Unhealthy Soil), Shin-Nihon Shuppansha (publishing company)

24© 2019 Koji TakakuraChapter 7 Effective ways to use compost•

Shunrokuro Fujiwara: Shinpan Zukai Dojo no Kiso Chishiki (Basic Knowledge on Soil, with
Illustrations, New Edition), Rural Culture Association Japan•

Shunrokuro Fujiwara: Taihi no Tsukurikata, Tsukaikata, Genri kara Jissai made (How to Make and
Use Compost, from Principles to Practical Application), Rural Culture Association Japan•

Toshihide Matsuzaki: Tsuchi to Taihi to Yukibutsu (Soil, Compost and Organic Substances), Ie-noHikari Association•

Masakazu Aoyama: Dojo Danryu Keisei Hokai no Dorama to Yukibutsu Riyo (Soil Aggregation,
Dramatic Processes of Formation and Collapse, and Use of Organic Substances), Rural Culture
Association Japan•

Amy Stewart, translated by Yoko Imanishi: Ningen ni Totte Juyo na Ikimono Mimizu no Hanashi (AStory of Earthworms, an Important Life Form for Humans), Asuka Shinsha Co., Ltd.

•

Nobuhiro Kaneko: Dojo Seitaigaku Nyuumon Dojo Dobutsu no Tayosei to Kino (Introduction to Soil
Ecology – Diversity and Functions of Soil Animals), Tokai University Press•

Kazunari Yokoyama: Zukai de Yoku Wakaru Dojo Biseibutsu no Kihon (The Basics of Soil
Microorganisms, Made Easy with Illustrations), Seibundo Shinkosha (publishing company)

25© 2019 Koji Takakura