Compost: Definition and Importance

• Compost is the product of decomposition of plant and animal wastes with various additives. It improves soil health by enhancing fertility, structure, and water-holding capacity.
• The word “Compost” is derived from the Latin word “Componere,” meaning “to put together.”

Why Composting?

• Direct application of plant and animal wastes into soil results in slow decomposition with little to no improvement in soil quality. Composting transforms these wastes into nutrient-rich organic matter, promoting sustainable agriculture.

Composting: Process and Principles: Composting is the process of converting organic matter into manure by accelerating the fermentation process under controlled conditions.

Key Principles of Composting:

1. Purpose: Convert organic matter into growth-promoting substances for soil improvement and crop production.
2. Microbial Activity: Decomposition is driven by microbes that require:
   • Moisture: 50% of total pore space.
   • Aeration: 50% air space for proper fermentation.
   • Carbon to Nitrogen Ratio (C:N): Ideal range of 20:1 to 30:1.
3. Soil Microorganisms: Earthworms, especially Eisenia foetida, help produce stable humus and soil crumbs through digestion.
4. Additives: Lime, gypsum, rock phosphate, and nitrogen accelerate decomposition and enhance quality.

Composition of Compost: The composition of compost varies based on the raw materials used. Here are average values:

Methods of Composting

Composting methods vary based on materials, process control, and environmental conditions. Here are the major types:

a) ADCO Process (Agricultural Development Company)

• Developed by: Hutchinson, H.B., and Richards, E.H. (1914-1918) at Rothamsted Experimental Station, England.
• Materials:
  • Raw material: Straw and other farm wastes.
  • Starters: Ammonium sulfate, ammonium phosphate, superphosphate, muriate of potash, ground limestone, and urea.

Procedure:

1. Spread raw materials in layers.
2. Sprinkle ammonium sulfate solution.
3. Apply powdered limestone as a broadcast.
4. Continue layering until a convenient heap height is built.
5. Fermentation occurs over 3 months, resulting in a product similar to farmyard manure (FYM), called “Synthetic FYM.”

Outcome: The ADCO process was patented, and commercial starters were marketed under ADCO Accelerator and ADCO Complete Manure.

b) Activated Compost Process

• Developed by: Fowler and Ridge (1922) at the Indian Institute of Science, Bangalore.
• Materials:
  • Raw material: Straw and farm wastes.
  • Starters: Cow dung, urine, night soil, sewage, and sludge.

Procedure:

1. Treat farm wastes with a decoction of cattle dung and urine to promote even fermentation.
2. Pile the compost in 3-4 feet heaps and turn regularly while keeping moist.
3. High temperatures occur in the first week.
4. After one week, volume reduces. Add more raw materials and mix thoroughly.
5. Maintain 25% of fresh material and decoction for continuous fermentation.

Outcome: Compost is ready within 5-6 weeks. Night soil, sewage, and sludge can be incorporated for enrichment.

c) Indore Process

• Developed by: Howard and Ward at the Indian Institute of Plant Industry, Indore.
• Materials:
  • Raw material: Straw or organic farm wastes.
  • Starters: Cattle dung, urine, earth, and wood ashes.

Procedure:

1. Dig a compost pit (30 x 14 x 3 feet) with sloping sides.
2. Spread raw material in 3-inch layers.
3. Sprinkle urine, earth, and wood ashes.
4. Add a 2-inch layer of dung. Repeat until the heap reaches 3 feet above ground.
5. Provide aeration using 4-inch diameter pipes at 4-feet intervals.
6. Water twice daily and turn the heap thrice:
   • First: End of the first fortnight.
   • Second: End of the second fortnight.
   • Third: After two months.

Observations:

1. After 10 days: Fungal growth, reduced heap height, and onset of humus synthesis.
2. After 2 months: Darkened material, bacterial decomposition, and nitrogen fixation.

Outcome: Compost is ready within 3-4 months. One pair of cattle can produce 50-60 cartloads annually.

d) Bangalore Process

• Developed by: Bangalore Agricultural Institute, India.
• Materials:
  • Raw material: Farm waste.
  • Starters: Cattle dung and urine.
  • Additives: Lime, rock phosphate, gypsum.

Procedure:

1. Prepare a pit (20 x 4 x 3 feet).
2. Spread raw material in 6-inch layers.
3. Sprinkle cattle dung and urine decoction.
4. Repeat layering and keep moist.
5. Additives like lime and rock phosphate accelerate decomposition.

Outcome: Compost matures within 3-4 months.

e) Vermicomposting

• Process: Composting using earthworms (Eisenia foetida).
• Procedure:
  1. Prepare a composting bed with farm waste and cow dung.
  2. Introduce earthworms to the material.
  3. Turn the material regularly.
  4. Maintain moisture and aeration.

Outcome: Rich, fine compost with enhanced nutrients, ready in 4-6 weeks.

Other Methods of Composting

1. Coimbatore Process: Traditional composting with dry leaves and cow dung.
2. Rainwater Compost: Composting during the rainy season using farm waste.
3. Rural Compost: Farm-level composting using locally available materials.
4. Urban Compost: City-based composting using municipal waste.
5. Mechanical Compost: Industrial-scale composting using machinery.