As a by-product of biogas plant; Bio gas manure is generated by fermentation of organic matter. The fibrous material, inorganic solids that do not digest or convert into methane either settle down or come out as slurry. This contains elements including nitrogen, phosphorus, potassium, and trace elements zinc (144ppm), manganese (188ppm), iron (3550ppm), copper (28ppm). The nitrogen in organic matter is conserved completely when processed through biogas plant whereas in open composting most of the nitrogen gets leaches out or is evaporated. Using Biogas manure is one beneficial option as it doesn’t smell bad or allows insect growth; it increases micronutrients in soil and water retention capacity; has lesser methane exposure; that results in improved taste, smell, and size of crops.
Nitrogen, phosphorus and potassium are essential nutrients for plants in a fertiliser. Plants are capable of absorbing nitrogen in its mineral form (NH4-N) for their vital functions. Through a process of anaerobic fermentation, the proportion of mineral nitrogen increases by about 20%. Liquid and solid manure that has not been fermented contains more nitrogen in organic form, the mineralisation of which may take several years. That is why the fertilising properties of the digestate on agricultural land are better than those of liquid or solid manure. Apart from the NH4-N, digestate contains phosphorus and potassium, two other essential nutrients.
Biogas manure is a good fertiliser for crops and improves the soil fertility, soil structure and yields of crops. It is often even better than regular Farmyard Manure (FYM) and may also reduce the use of chemical fertilisers. With the right rate of 10 to 20 tons/ha in irrigated areas and 5 tons/ha in dry farming, crops can show significant increase in yields. Indeed, biogas manure increases crop revenues by 25 percent on average.