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Composting Overview

Index
1	Operation
2	Composting of livestock excrement
3	The composting process
4	To achieve best composting
5	Composting conditions and process
6	Composting methods
7	Typical composting methods
8	Composting temperature curve
9	Composting process examples
10	Calorie Calculation
11	Composting of poultry-dung
12	Deodorizing tank
13	Structure of COMPO
14	Concept of composting
15	Purpose and effect of composting
16	Things you should keep in mind about composting
17	Present situation and issues of compost application

1. Operation

2. Composting of livestock excrement

Unprocessed livestock excrement generally contains high moisture. It is very hard to handle and will damage roots of crops, disturbing the plant growth when applied raw.

"" If an immature compost is applied....""
	It produces harmful gas and plants get damaged.

3.What is composting process

Composting process aims to turn excrement into manageable high-quality compost by letting aerobic bacteria remove the organic matter, which is produced during the decomposition process, under aerobic conditions, while evaporating moisture in the excrement.

4.To achieve best composting

Ensuring even air flow throughout excrement is important to achieve the best result because aerobic bacteria need air to continue growing and be active .

Air also plays another important role to produce manageable, low-moisture and high-quality compost. Air is needed to let the moisture evaporate from the heat released during the composting process.

This heat also kills pathogenic bacteria and weed seeds.

5.Condition and process of composting

To promote aerobic composting, creating the ideal environment for growth of aerobic bacteria is important. There are five conditions for letting aerobic composting happen.

1. Aliment (organic matter)

To promote composting, organic materials to be decomposed as energy source for bacteria is essential.
Organic materials include various matters.

• Easy decomposition organic matters---(Ex.) fat, sugar, carbohydrate, protein
• Hard decomposition organic matters---(Ex.) fiber, hair

Since hard decomposition organic matters require long time to be broken down, rapid composting process, such as COMPO does, cannot decompose them. Such matters are decomposed very slowly in the field, therefore they don't produce any toxic gas such as NH₃.
On the other hand, degradable organic matter decomposes rapidly if thrown into the field and creates problems such as NH₃ generation.
However, since degradable organic matter decomposes very easily in COMPO and becomes an effective energy source, there is no gas generation when it's applied to the field.

2. Temperature

Bacteria needs certain temperature to be active. The ideal temperature inside COMPO is 60 to 70 Celsius. Keeping this temperature also helps to evaporate the moisture and dry the excrement.

3. Moisture

Aerobic composting requires an adequate moisture level. If the level is too high, air circulation is disturbed and composting fails. If the level is too low, due to the lack of moisture, composting also fails. To achieve the ideal composting, 30% to 55% moisture level in COMPO is necessary.

4. Air

To promote aerobic composting, providing sufficient air evenly to excrement is essential. At a high moisture level, air flow is disturbed and air can hardly be supplied. Therefore adequate moisture and air-flow control are necessary.
The moisture control of COMPO is done using source manure. Also the blades of the agitator constantly mix the manure so that the air openings are always in motion, which let the air reach the whole material evenly and thoroughly. This agitation is also necessary for the evaporation of moisture.

5. PH

While excrement is generally acidic (around PH6.0), PH 8.0 to 9.0 is ideal for bacterial activity. As aerobic composting is processed, due to the large amount of NH₃ generation, it turns into alkali, then the ideal environment for aerobes are set in place.
On the other hand, in the anaerobic environment, as a result of large generation of lower fatty acid, the acidity level gets higher and therefore the PH level gets lower (PH5.0 to 6.0).
In this environment, aerobes cannot grow, therefore aerobic composting is stopped (it starts to produce sour odor)
However it can turn back to normal when the PH is adjusted and air is supplied.

6.Composting methods

Decomposition rate of organic matter varies depending on the composting method.

• Depositing manual mixing method:1.0%/day
• Scoop method, depositing composting method:1.5%/day
• General airtight composting machine:2.5%/day

*Adding sawdust for moisture control significantly lowers the decomposition rate, because sawdust contains large amounts of persistent cellulose.

7.Typical composting methods

8.Composting temperature curve

9.Composting process example

10.Calorie Calculation

During excrement fermentation, total calories produced from 1kg of decomposed dry matter is generally 4,500kcal. To evaporate 1kg of moisture requires 800kcal. The fermentation and drying capacity can be calculated from the balance of the caloric production and expenditure.

	3.0% per day			Holding time - 10 days
-Decomposition rate	3.0%	x	10 days	= 30%
-Decomposing amount (reduced dried material)	4,000kg	x	0.3	=1,200kg
-Product amount of dried material	4,000kg	x	0.7	=2,800kg
-Product amount of material	2,800kg	/	0.7	= 4,000kg
-Product amount of moisture in the material	4,000kg	-	2,800kg	=1,200kg
-Produced calorie from decomposition of dried matter	1,200kg	x	4,500kcal	=5,400,000kcal
	6,000kg	-	1,200kg	=4,800kg  Amount of moisture evaporated
-Calories required for moisture evaporation	4,800kg	x	800kcal	=3,840,000kcal
In this case, calories produced by decomposition of dried matter is greater than calories required to evaporate moisture, therefore the process is feasible.

11.Compostiong of poultry excrement

Ammonia generation by livestock

Unlike excrement from other livestock (i.e. cattle), poultry excrement appears in one form (faeces and urine together) and contains more nutritious constituents such as nitrogen, phosphoric acid and calcium. Therefore poultry-dung performs well as a fertilizer rather than soil ameliorant. However if nitrogen-rich poultry-dung is applied raw on the soil, the organic compound in the manure starts to decompose quickly, producing a large amount of ammonia gas, resulting in damage of the plants' roots.

Fermented poultry-dung on the other hand, is useful for plants because the nitrogen is already decomposed and discharged as ammonia gas, or decomposed into nitric acid or nitrous acid, during the fermentation process.

Therefore there is damage for plants resulting from ammonia gas when applied to the field.

Adding sawdust can improve the air circulation of the poultry-dung, which contains high moisture, to help fermentation. However, since lignin and cellulose in sawdust slow down the decomposition process, fermentation and decomposition will continue to process in the soil, resulting in damage for plants.

12.Deodorizing tank

During the aerobic fermentation process, the organic materials produce heat, ammonia gas,

CO₂, H₂O etc. Among them, the level of fetid ammonia gas is around 3,000 ppm. In this tank, the ammonia gas is biologically removed (bio-filter) and deodorized using sawdust.

Basic mechanism

When the fetid gas passes through sawdust, the odor is absorbed by sawdust or dissolved into moisture that exists between sawdust particles or in sawdust itself. With air blown for long period of time, the sawdust starts to ferment and bacteria begin to breed. The bacteria decompose the NH₃ ammonia and deodorizing is processed.

Offensive odor in livestock farm mainly comes from ammonia. Ammonia easily absorbs moisture and turns into odorless nitric and nitrous acid under the aerobic environment with the activity of bacteria in the soil, especially nitrifying bacterium, to reduce the overall odor level.

Biological deodorization requires a certain environment. The temperature of the material when removed from COMPO (excrement fermentation unit) is as high as 60-80 Celsius but the temperature has to be at most 50 Celsius to introduce it into the deodorizing facility. Temperature management is one of the most important points in operating the facility.

13.Structure of COMPO

14.Concept of composting

Definition of composting

Composting is defined as "the microbial decomposition of biological waste under a controlled environment where the waste reaches to the manageable, preservable and environmental-safe state that can resolve into soil" (Goluke 1997). In other words, composting is "to decompose organic matter until a certain degree, in an aerobic environment". During the process, odor source is also decomposed and evaporated, and moisture level is reduced.

If the waste is completely decomposed, the resulting compost does not provide sufficient organic contents to the soil. Moreover it adversely affects the physical characteristic of soil such as expansion, softening, water-holding capacity and permeability as well as chemical characteristics, which also have a harmful effect on soil ecology. On the other hand, however, if the decomposition of the organic materials are not mature enough, the aerobic decomposition continues to process in the soil, resulting in oxygen deficit land. The proper condition of compost is supposed to be somewhere in between those two, but generally considered to be the state where no negative impact on crops is present. At this viewpoint, the definition above does not precisely define composting.

Composting phenomenon

The biological waste contains organic materials such as sugar, protein, carbohydrate and fat, which are metabolically decomposed or broken down into low molecular weight by bacillus, actinomycete and filamentous bacterium during the composting process. Such series of processes is referred as "Composting phenomenon". The resulting compost becomes a nourishment source for plants and realizes the circulation of materials.

15.Purpose and effect of composting

Purpose of composting

To Utilize the finished compost as organic fertilizer. Auxiliary effects for the soil are also expected.

Effects of compost

1. Cycling active constituents in the soil

Active constituents such as N, P, K, which originally exist in the soil, are absorbed by plants to grow. Composting is a part of the cycling system that move those constituents back to the soil.

2. Stabilize the unstable organic materials

Biological waste is unstable because it contains large amount of organic materials to be decomposed by bacteria. If it is applied raw, aerobic decomposition is quickly processed in the soil, resulting in oxygen deficit land. This prevents roots of crops from breathing.
Composting lets the aerobic decomposition happen during the process to stabilize the organic materials so that the cycling system is accomplished when applied to the soil.

3. Eliminate the filthy impression

Composting turns livestock excrement into something that looks like soil. The filthy odor is eliminated and the heat from aerobic decomposition dries them out. The dried compost is easy to manage, which improves operating efficiency, and does not have the original dirty image anymore.

4. Kills or deactivates bacteria, harmful insects, weed seeds etc.

When the composting is processed well, it naturally heats up. The temperature is high enough to meet the requirement of EPA (US Environmental Protection Agency) standard (EPA requires that the material should be exposed more than three days at 55 Celsius or higher) to kill harmful bacteria and vermin (including eggs).
Also deactivation of weed seeds in the livestock excrement prevents the disruption of a botanical ecosystem that could be caused by foreign seed.

5. Reduce the volume of food waste

Food waste with a high water content, such as kitchen garbage, tends to lower the incinerator performance and have a possibility of dioxin contamination when burned. Instead of taking those risks, composting food waste, that is, decomposing organic materials, is a possible way to reduce the garbage volume.

6. Decompose biodegradable plastics

Biodegradable plastics were thought to be persistent in the soil and hard to make a practical application. However recent research confirmed that composting the biodegradable plastics could accelerate the decomposition (Kimura and Nakasaki et al., 1999), which enhances the possibility that society starts to use biodegradable plastics instead of petroleum-derived general-purpose plastics, which can change the resource recycling system.

7. Preserves a function as biological pesticide

Some compost keeps a bacteria group which controls plant disease and acts as a biological pesticide.
（Nakasaki et al.: A New Operation for Production  Disease-Suppressive Compost from Grass Clippings,  Appl.Emviron.Microbiol,64(10),4015-4020,1998）

As described above, compost has many benefits. Besides that, it is easy to produce and approachable.

Composting does not require any special bacteria, therefore the cost is very low. All you need is to allow the material (waste) to contact the oxygen (air) . This simple and easy way is the reason composting is very approachable.

16.Things you should keep in mind about composting

• Offensive odor

Generation of sulphur compound (at the first stage of reaction) and ammonia (while organic decomposition is intense after the temperature rises) causes offensive odor.
Bio-filter method using nitrifying bacterium is the cheap and effective countermeasure.

• Moisture adjusting material

Livestock excrement and food waste originally contain more than 85% water, therefore moisture control is essential for composting.
At high moisture level, water gets into and between the materials, which blocks oxygen supply to the bacteria that reside in the materials. As a result, the bacteria, which are supposed to process the compost, stop growing.
Expandable, softening and dry materials such as wooden chips, saw dust and chaffs are currently often used to ensure the air passage.
However if too many bulking agents are added to the waste, this can lead to an increase in compost amount as well as the operation cost.

17.Present situation and issues of compost application

1. Present situation in compost application

There are not so many agricultural farmers who actively utilize compost. However for the farmers who are using compost, they tend to be enthusiastic and most of them produce their own compost.
Vegetable farmers use compost the most. The objects of application are rice, fruit tree, oats and tea etc.
Application amount is 1-2 ton/10a for rice, 5 ton/10a or higher for facility-grown vegetables, 3-5 ton/10a for fruit tree and the amount greatly varies for garden-grown vegetables depending of the species.
Establishing a reasonable guideline for application technique is important from the point of view of environmental preservation.

2. The application amount from the view of environmental preservative

The application of adequate amount of livestock compost does not only nourishes crops but also improves the characteristic of the soil physically, chemically and biologically. However overuse the compost causes various adverse affect. There is a proper amount that can ensure the high quality harvest and yet does not cause any environmental pollution.
There is some compost whose mineralization speed is very slow. Such compost does not nourish soil at earlier stage, therefore crop may show poor initial development from lack of nourishment.
Applying the nourishing compost on the soil where chemical fertilizer is already used, excessive nutrients can impair the quality of crops and decrease the harvest. Drainage can also cause environmental pollution.
Livestock compost requires a long time to decompose. The compost builds up in the soil and discharges its nutrients over the long period of time. Compost is great to get solid power. However if it is used year after year, the amount of mineralized nutrients is increased and accumulated (cumulative effect.)
Therefore, the basic principle of the application is, to balance the nutrients in the soil, taking the cumulative effect in consideration, by adding chemical fertilizer or reducing the amount of compost.
The Livestock Environmental Measure Committee provides following basic guidelines for the application amount of livestock compost.


1. To ensure good quality and harvest of the crops and prevent any negative effects

For the requirement of three principle nutrients, conform to the application standard by crop, that was published rather recently. Even when a large amount of livestock compost is applied, the total amount of three nutrients, together with the active constituent in the compost and chemical fertilizer, has to meet the standard.

2. When the chemical fertilizer does not give any instruction about compost application.

Amount of compost can be calculated as follows. Based on general substitution rate (cattle: 30%, pig or chicken: 60%), reduce the amount of nitrogen in the chemical fertilizer's application standard. From the relative efficiencies of nitrogen in the compost (cattle compost: 30%, pig compost: 50%, dried chicken manure: 70%), calculate the amount of compost which contains enough nitrogen to substitute the reduced nitrogen from the chemical fertilizer.
The relative efficiencies above are general figures and can vary depending on compost processing, bulking agent and degree of maturity. If other numbers are specified, use that figure.
Compost application amount (t/ha) = Nitrogen requirement(kg/ha)×Substitution rate(%)/100×100/ compost nitrogen content(%)×100/relative efficiency(%)×10^-³
The balance of three principle nutrients in livestock excrement is usually different from the application standard. Therefore, when calculation is done based only on one of the nutrients, other nutrients are likely to be excessive.
If that is the case, when any of the three nutrients is excessive, reduce the amount of the compost so that the excessive nutrient meets the application standard. For the other nutrients, compensate them with chemical fertilizer to keep the amount of nutrients balanced as stated in the standard.

3. After the amount of compost is determined

Calculate the total amount of nitrogen contained in both chemical fertilizer and compost. Assuming that the total amount of nitrogen is applied, if nitrite nitrogen in seepage water does not exceed the standard value(100mg/L), that amount of nitrogen is the maximum for the crop quantity and quality. If the nitrite nitrogen appears to exceed the standard, calculate the total nitrogen amount that makes the level 100ml/L based on previous test results, then use the figure as the maximum value.

If this calculation method is applied, for feed crop, the maximum amount of total nitrogen from compost will be around 200kg/ha, and maximum amount of total nitrogen including chemical fertilizer will up to 350kg/ha.

3. Application technology for environmental preservation

The fertilizer or organic fertilizer application technology for environmental preservation refers to the application technique to increase the nutrient utilization rate (absorptivity) of the field crop, and to prevent the substances from discharging to the environment at the same time. If fertilizer or organic materials are applied in a full-layer, not all nutrients can reach the roots of the crop. Therefore topical (local) application is used to maximize the efficiency.
The percentage of uncollected nitrogen for total applied nitrogen is called nitrogen balance. Application technology for environmental preservation is the technique to make the nitrogen balance as minimum as possible.
Topically applying the adjustable fertilizer and compost, with reduced amount of input nitrogen, will increase the utilization rate of nitrogen. As a result, the nitrogen collected by the crop remains the same while the nitrogen balance is significantly lowered.

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