Composting is the natural process of decomposition of organic materials by microorganisms under controlled conditions. Raw organic materials such as crop residues, animal wastes, green manures, aquatic plants, industrial wastes, city wastes, food garbage etc. enhance their suitability for application to the soil as a fertilizing resource, after having undergone composting. The end product of the process is compost or humus which, is of value in agriculture. In addition, compost could be considered as a value added product of organic materials, which has a high commercial value when compared to many other forms of organic materials.

AIM OF THE PROJECT
Increase sustainable crop production, improvement of long-term soil fertility for better farmer livelihood, alleviating rural poverty and reduce foreign exchange drain on chemical fertilizer imports.

OBJECTIVES
Long-term objectives:

• Increase crop productivity.
• Improve soil fertility.
• Reduce chemical fertilizer imports.

Short-term objectives:

• Use of freely available organic materials in crop production.
• Identification and utilization of new sources of organic materials.
• Generate organic materials such as green manure, animal manure etc.
• Compost production using freely available organic waste materials such as urban waste, industrial waste, animal waste, domestic waste   etc.
• Increase production of high quality organic fertilizer by introducing correct technologies.
• Increase organic fertilizer production at different levels such as large, medium and small  scales.
• Quality control of organic fertilizer production through implementing SLSI standards.
• Generate more employment opportunities by promoting commercial organic fertilizer
   production.
• Increase organic fertilizer marketing system.
• Improvement of infrastructure facilities for commercial organic fertilizer production.
• Set-up analytical service centers in every province to analyze organic fertilizer,
   chemical fertilizer, plant, soil and water samples.
• Popularize IPNS technology.
• Improve soil fertility and conserve agricultural lands in sustainable manner.
• Increase the efficiency of chemical fertilizers by introducing IPNS technology.
• Increase crop productivity by introducing correct soil fertility management practices as   well as by making adjustments to current nutrient management practices.
• Increase farmer income for better livelihood and alleviating poverty.
• Develop technology packages in relation to sustainable agriculture systems.
• Minimize environmental pollution.

MAIN ACTIVITIES

• Conduct training and awareness programmes for different target groups aiming availability of organic manure/materials, their suitability for organic fertilizer (compost) production, beneficial effects of organic fertilizer use in crop production, efficient compost production, correct technologies in composting, quality compost production, IPNS technology, beneficial effect of organic materials use in crop production etc.
• Collect freely available organic materials such as animal manure, crop residue, green manure, aquatic plants etc. for compost production.
• Cultivate green manure crops.
• Improve and establish diary farms to collect manure for compost production.
• Produce compost at small, medium and large scales.
• Encourage point separation of municipal solid waste.
• Produce compost out of municipal solid waste, industrial waste etc.
• Determine plant nutrient availability of different organic materials.
• Characterize compost and upgrade according to the SLSI standards.
• Formulate substitution levels of chemical fertilizers when organic manure and compost are used under different soil/crop combinations to cut down chemical fertilizer use.
• Determine on farm soil fertility status and develop suitable integrated plant nutrition management packages. 
• Establish analytical service laboratories in different areas.
• Promote organic manure and compost use in crop production. 
• Conduct awareness programme on precise soil and plant nutrition management systems.
• Formulate IPNS policy for Sri Lanka.
• Strengthen technologies in relation to IPNS.
• Conduct on farm demonstration to popularize IPNS technology.
• Develop technologies in relation to organic fertilizer production.
• Develop suitable inoculums to accelerate the compost production.
• Conduct mass media programmes on compost production and IPNS technology.
• Strengthen marketing channels of compost.

EXPECTED OUT PUT

• Increase food crop production by 50%.
• Increase farmer income by 50%.
• Increase organic fertilizer production by 400%.
• Increase use of organic manure and organic fertilizer by 100%
• Cut down chemical fertilizer imports per year by 25%.
• Save 25% expenditure on fertilizer imports.
• Utilize waste materials and freely available organic manure for crop production.
• Minimize environmental pollution by adopting correct waste management practices.
• Production of quality compost according to the SLSI standards.
• Minimize soil and water pollution by implementing IPNS technology.
• Minimize soil degradation.
• Improvement of long-term soil fertility.
• Increase animal husbandry.

 

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 Principles in Composting

 

Composting may be defined as a biochemical process by which diverse and mixed group of microorganisms breaks down organic materials to humus. Therefore, optimum conditions should be maintained to maximize the microbial activity in the compost production system.

 

Influencing Factors

• C:N ratio in raw materials.

• Moisture content
• Aeration
• Reaction
• Shredding
• Turning
• Microbial activity
• Nutrient supply

C:N ratio in raw materials

• Low C:N ratio in raw materials is beneficial for decomposition.
• Low C:N ratio increases microbial activity.
• Green leaves are low in C:N ratio
• Do not use materials with high C:N ratio alone.
• Arrange high C:N ratio and low C:N ratio raw materials alternatively.

Moisture Content

• Moisture is necessary for microbes
• If moisture is low microbial activity is also low
• Too much of moisture is not suitable.
• Optimum moisture should be maintained throughout the process.
• A suitable cover should be used to maintain the optimum moisture content.

Aeration

• During the composting process O₂ should be well supplied and CO₂ should be easily released.
• If not anaerobic condition may take place.
• Under the anaerobic condition bad odor may appear.
• To obtain good aeration arrange different types of raw materials in layers
• Turning may increase the aeration.
• Keep the reasonable width in heap method (maximum 6-7 feet).  

Reaction

• Reaction is important for microbial activity.
• In the alkaline condition activity of microorganisms may reduce.
• Therefore, liming materials such as ash, lime and dolomite are not recommended.
• In addition, under the alkaline condition N in raw materials may loss as NH₃.
• Ash could be added after completion of the composting process.

 

Shredding

• Shredding or chopping of raw materials in to small pieces will increase the microbial activity.
• Increase aeration
• Optimum size of pieces is almost 5 cm.
• Increase surface area for microbial activity.
• Shredding is laborious.
• Recommended raw materials such as banana trunk, hard raw materials etc..
• In general shredding is not recommended due to high cost.

 

Turning

• Increase aeration
• Increase decomposition
• Undecomposed raw materials may mix properly.
• Facilitate to keep the optimum moisture by adding water or drying.
• It is laborious.
• Maximum 3 times turning is recommended

 

Microbial activity

• Add inoculants after every 2-3 layers of raw materials.
• Inoculants may increase the microbial activity and increase the decomposition.
• In addition to compost decomposed garbage or any other organic materials are suitable as inoculants.

 

Nutrient supply

• Addition of N fertilizers reduces the C:N ratio and increase the decomposition of raw materials.
• Increase the microbial activity.
• Increase decomposition.
• Rock phosphate is suitable to enrich compost with P

 Methods of Composting

 

There are a few methods available for production of compost namely:

(1)   Heap method

(2)   Pit method

(3)   Cage method

(4)   Barrel method

 

(1)   Heap method

 

• Easy and very popular  method
• Decomposition is faster
• Aeration is easy
• Easy to maintain optimum moisture level
• Turning is easy
• Suitable for both large and small scale production systems
• Popular among commercial producers
•  Heap size could be arranged according to availability of raw materials
• Heap should be covered with suitable covering material 

(2). Pit method

·         Suitable for small scale compost productions

·         Suitable for dry areas

·         Laborious method

·         Expensive to make a pit

·         Contamination with soil particles is high.

·          Poor aeration

·         Decomposition is slow

·         In rainy seasons difficult to maintain optimum moisture level

·         Turning is difficult

·         Not suitable for commercial compost productions

·         Create odor in many occasions

·         Not considered as a successful method

 

(3). Cage method

• Suitable for home gardens and small farm lands
• Daily collection of raw materials can be used
• Suitable for areas where raw materials are limited
• Good aeration
• No odor
• Drying quickly. (Optimum moisture should be maintained regularly).
• No turning involved
• Decomposition is slow
• No systematic preparation of layers
• Open for air and rain
• Top of the cage should be covered with coconut frond to minimize drying and also to protect from rain water  

(4). Barrel method

• Suitable for urban areas and home gardens
• Daily collection of raw materials can be used
• Poor aeration
• Create bad odor in many occasions
• No turning involved
• Decomposition is slow
• No systematic preparation of layers
• Barrels are costly

 

Steps in Compost Production

 

Compost is a mixture of decayed organic materials decomposed by microorganisms in a warm, moist and aerobic environment releasing nutrients into readily available forms for plant use.

 

Selection of a site for compost production

·         Raw materials should be available

·         Water should be available

·         Site should not be in the close vicinity to drinking water well.

Preparation of a production site

• Choose a shaded and well- drained area
• Clean the site
• Remove stone and unwanted materials
• Level the site if possible

 

Collection of raw materials

• Locally available raw materials should be used
     
     
     

Green leaves

Weeds

Banana leaves

Banana trunk

Salvenia

Sow dust

Vegetable peelings

Crop waste

Animal waste ( Cow-dung, Poultry manure)

 

Materials needed for compost production

(1)   Heap method

• Raw materials
• Water
• Covering materials
• Inoculants
• Fork mammoty (Optional)

(2)   Cage method

• Raw materials
• Water

• Stakes to prepare a cage
• Coir rope
• Coconut frond
• Inoculants  

(3)   Pit  method

• Prepared pit
• Raw materials
•  Water
• Covering materials
• Inoculants

(4)   Barrel method

• Suitable Barrel or compost bin
• Raw materials
• Water
• Inoculants

Procedure

     
     

Heap and Pit methods

• To accelerate the decomposition of raw materials maintain the maximum height of the layer up to 15 - 30 cm.  
• As the 1^st layer weeds or tree loping or leaf fall or any other suitable raw material can be used.
• As the second layer green leaves, grass or Salvenia can be added.
• Add water if raw materials are dry or not contain sufficient moisture.
• Then add small amount of inoculants to add microorganisms to accelerate the decomposition.
• As the 3^rd layer add banana leaves.
• As the 4^th layer leaf fall could be used.
• As the 5^th layer Animal waste can be used.
• Then add inoculants again.
• As the 6^th layer add pieces of chopped banana trunk.
• As the 7^th layer leaves can be added.
• Then add again small amount of inoculants.
• Similarly, continue making the pit or heap with different raw materials up to a reasonable height.
• Finally add enough water and cover the heap or pit with a covering material.
• In the heap method always keep a space between the cover and the ground for ventilation.
• Every 4-5 days interval open the cover and check the moisture content inserting a pole in to the compost heap or pit.
• If moisture content is not enough add enough water and cover the heap or pit again.
• After 3-4 weeks remove the cover and turn the heap or pit properly (1^st turning).
• During the turning add inoculants to increase the decomposition again.
•  After the turning half decomposed raw materials arranged as a heap or in the same pit.
• Again cover the heap or pit as mentioned earlier.
• Similarly, check the moisture every 4-5 days and add water if necessary.
• After 7-8 weeks again remove the cover and turn properly (2^nd turning)
• At this stage also add inoculants to increase the decomposition.
• During the 2^nd  turning too if  moisture content is not sufficient water should be added.
• Partially decomposed raw materials again arranged as a heap or pit and cover as earlier.
• After the 2^nd turning too check the moisture content every 4-5 days interval and if moisture is not sufficient water should be added.
• After 11-12 weeks remove the cover and turn compost properly (3^rd turning).
•  After mixing make the heap or pit again and cover as earlier. 
• After 3 months in many occasions materials are well decomposed and compost can be used for crop production. 
  In general, use any kind of suitable raw material as any layer of the heap or pit. However, in both methods arrange alternatively slow decomposition and fast decomposition raw materials to accelerate the decomposition rate.   

 Cage and barrel methods

• Prepare a cage with stakes or placed a compost barrel or compost bin in a suitable place.
• Advantage of these methods is raw materials can be added at any time.
• Cage or barrel can be filled with different raw materials alternatively according to their decomposition rate.
• In addition, inoculants can be added to increase the decomposition of raw materials.
• Since drying is fast in the cage method water should be added regularly to maintain the reasonable moisture content inside the cage.
• In addition, top of the cage can be covered with coconut frond or with suitable covering materials to maintain the optimum moisture content inside the cage.
• Produced compost could be collected from the bottom of the cage or barrel.   

            Role of compost in soil fertility is known to improve crop production directly and indirectly, by improving the soil properties. There are several reasons for using compost but its main contribution is as a supplier of humus substances to soil, thus supplementary major plant nutrients and being a good source for providing secondary and micronutrients. One of the important contributions of compost is the high organic matter fraction, which improves the physical, chemical and biological properties of soils.

 

Benefits of using compost

·         Increase yield.

·         Improves overall soil fertility.

·         Provides humus or organic matter.

·         Provides vitamins, hormones and plant enzymes which are not supplied by chemical fertilizers.

·         Acts as buffer to changes in soil pH.

·         Compost is free from pathogenic organisms, weeds and other unwanted seeds.

·         Nutrients are readily available.

·         Easy to apply when compared to other organic manures.

 

For more information-

Director (Organic Fertilizer Unit)
Ministry of Agriculture
Govijana Mandiraya
80/5 Rajamalwaththa Lane
Baththaramulla

T.P. 011 –  2885409
Fax  011 – 2885409 / 2888910