WastG: An instrument for quantifying Methane and Nitrous Oxide from excreta

Technology Details:

India possesses 537 million livestock including 190 million cattle and 109 million buffaloes in different states and primarily being fed on the fibrous diet. The diet composition frequently changes with the region and season and based on the feeding regimes the nutrient utilization efficiency of the livestock is also quite variable. For example, the nitrogen use efficiency depends on the protein content of the diet, extent of protein intact with the indigestible fibre, productivity level etc. resulting into variable nitrogen excretion influencing ammonia and nitrous oxide (N2O) emissions. Animal excreta is also a major source of methane (CH4) emissions; however, the aerobic storage of the excreta in Indian conditions probably restrict the CH4 emission. Nevertheless, the emission of CH4 is still possible from the deep inner core of the excreta heap. On the other hand, the aerobic storage prompts the emission of N2O and ammonia from the stored excreta.

Livestock excreta (dung) contains a large fraction of organic matter that remains undigested during fermentation/ digestion in the gastrointestinal tract of the animals. The quantity and type of greenhouse gas(es) produced from the excreta depends upon the storage/disposal system. When the livestock excreta consisting organic material decomposes in anaerobic environment as followed in developed world, the methanogenic archaea produce methane. Similarly, the storage of excreta as liquid in lagoons, ponds, tanks or pits also leads to anaerobic decomposition and production of significant quantity of methane. In India, the excreta disposal is entirely different from the developed countries and majorly handled as a solid in the form of heap/stacks in open environment. The storage of excreta as heap leads to the aerobic decomposition where N2O is produced in large quantity with less CH4.

No primary data is available on the GHG emissions from the excreta under Indian conditions. A few reports on the GHG emissions from excreta in India using IPCC tier systems. These estimates for the CH4 and N2O emissions from the excreta are majorly based the IPCC emission coefficients, which do not depict the real scenario of excreta storage in India. The instrument WastG is developed by the ICAR-National Institute of Animal Nutrition and Physiology, Bengaluru for quantifying methane and nitrous oxide emissions from excreta while mimicking the field conditions of aerobic storage in India.