Composting

What is composting?

A biochemical process by which diverse and mixed group of microorganisms breaks down plant and animal materials (organic materials)in  to humus.

It is a must to maintain optimum conditions such as temperature and moisture in the compost production system to maximize the microbial activity.

Following conditions should be maintained to optimize the decomposition process,

Temperature -            65 ⁰C - 60 ⁰C

Moisture content -     50 – 60%

C:N ratio -                 30

Good aeration

Shredding or chopping of raw materials in to small pieces

Absence of alkaline conditions

Turning

Addition of N and P fertilizers

General Composition of the compost,

N        -3.75%

P        -0.18%

K       -2.74%

Ca     -9.49%

Mg    -0.92%

Raw materials for compost production,

Green leaves

Crop residues

Weeds

Salvenia

Banana leaves

Banana trunk

Sow dust

Vegetable peelings

Animal waste ( Cow-dung, Poultry manure)

Farm waste

Influencing Factors for the compost production process	Importance
C:N ratio in raw materials	C:N ratio should be low. Beneficial C:N ratio is 30 for decomposition process. Recommend Low C:N ratio in raw materials increases the microbial activity.      Ex- green leaves Arrange high C:N ratio and low C:N ratio raw materials alternatively for effective decomposition.
Moisture content	Optimum Moisture content : 50 – 60% should be maintained trough out the process. Microbial activity becomes low when the moisture content is low.  Recommend High moisture is not suitable since it can increase the disease spreading.
Aeration	Good aeration should be maintained. Turning increases the aeration. Poor aeration can create bad odors due to anaerobic conditions. Recommend Arrange different types of raw materials in layers to obtain good aeration.
Shredding	Shredding or chopping of raw materials in to small pieces increases,               The aeration.               The surface area for microbial activity. Recommend Optimum size of a piece is 10-15 cm. Raw materials with high C:N ratio should be cut in to small pieces.
Turning	Turning ,          Increases decomposition          Increases aeration          Undecomposed raw materials may mix properly.                       Facilitate to keep the optimum moisture by              Retaining moisture or drying. Recommend Maximum 3 times turning is beneficial.
Reaction	An important factor for microbial activity. Activity of microorganisms may reduce in the alkaline condition and  N in raw materials may loss as NH3. Recommend Due to this, liming materials such as ash, lime and dolomite are not recommended at the decomposition process. Ash could be added after completion of the composting process.
Microbial activity	Inoculants increase the microbial activity and increase the decomposition. suitable inoculants are Compost, decomposed garbage or any other organic materials. Recommend Add inoculants after every 2-3 layers of raw materials.
Nutrient supply	Can add N and P fertilizers Addition of N fertilizers,       Reduces the C:N ratio       Increase the decomposition of raw materials.       Increase the microbial activity. Rock phosphate is suitable to provide P.