Abstract: Background: Composting is a sustainable process to transform organic wastes into organic amendments, valuable as potting media or soil conditioner. Its immense benefits in organic farming have been acknowledged worldwide; but still it is not free of certain challenges. The main negative aspects of composting are emission of greenhouse gases and odorous molecules and the final product might contain toxic compounds, etc.
Methods: The different stages of composting are mainly initial phase, thermophilic stage and maturity/mesophilic stage. The initial stage last for 1-3 days during which simple organic sugars are mineralised by various microbes to form NH4, heat, CO2 etc. within a temperature range of 22-45 °C. During the thermophilic stage, the temperature reaches maximum (45-70 °C). This rice in temperature accelerates the breakdown of complex compounds like proteins, cellulose, hemicellulose, lignin, pectin etc. Lastly, during the mesophilic stage, the temperature slowly decreases due to reduced microbial activity, resulting from reduced availability of degradable matter.
Conclusion: It can be seen that different additives respond differently when added to composts. Higher dose of Biochar additives can increase pH of sewage sludge & facilitate better composting. Also, it can reduce green-house gases (GHG) emissions & consequently reduce N loss. Fly ash amended with additives like press mud and cow dung in 1:1:1 ratio has best effect on reproduction of E. eugeniae for vermicompost production. Additives like Zeolite can lower the bioavailability of heavy metals (Cu & Zn) by nutrient immobilization. Cellulose Decomposing bacteria can enhance storage quality, colour & reduce odor of finished compost. Poultry Manure & Vermicompost increases Soil Organic C & Aggregate Stability, Porosity to improve degraded Soil. Maize straw & Willow Biochar improves physical properties of Sandy Soil.Application of enriched bio-compost with reduced rates of inorganic N and P fertilisers increases bioavailability of soil nutrients (N, P and K). Also, it improves Soil Organic C & Soil Quality index. Acidified sawdust along with phosphate solubilizing rhizobacteria can improve C dynamics, root parameters & enhance grain yield, grain & root P in maize grown Soil.
