Course Content
Learn soil fertility, fertilizers and integrated nutrient management with Braimy- B.SC Agriculture
About Lesson
  1. C: N ratio:
  • If the OM is poor in N or C: N ratio is wide, biological activity diminishes and several cycles or successions of MO may be required to degrade organic materials.
  • The time of composting can be reduced by adding N sources of organic materials such as sewage sludge, legume residues, and slaughter house wastes, wastes of antibodies, yeast and N-fertilizers.


  1. Blending:
  • The organic materials are shredded into smaller pieces or ground to become more susceptible to bacterial attack due to exposure of more surface area.
  • The desirable size for composting is less than 5cm although large size can be also used.
  • Blending is not required if C: N ratio of organic materials is 25-50 although 30-40 may be a good range.
  1. Moisture:
  • Optimum moisture level of 50-60% may be quite satisfactory for aerobic decomposition.
  • Fibrous materials containing straws can be composted aerobically, 80% moisture can be maintained.
  • For anaerobic decomposition, the maximum moisture % is not important.


  1. Temperature:
  • Most of the mesophillic bacteria survive below 40 degrees centigrade.
  • High temperature is needed to kill pathogenic MO and weed seeds; generally, it occurs within 2-5 days of the start of composting.
  • Decomposition is the fastest in the thermophilic stage. The optimum temperature based on oxidation of OM into CO2 and H2O is about 600 C; but temperature of the composting material should not exceed 70 degrees centigrade.


  1. pH:
  • Initially the PH of compost heap is slightly acidic (pH 6) as is found in cell sap of the plants.
  • The production of organic acids during early stage of decomposition causes further acidification (pH4.5-5) but as the temperature rises, the PH increases, slightly alkaline (7.5-8.5).


Join the conversation
Scroll to Top