Farmers should adhere to specific guidelines and a standard operating protocol when using the Pusa biodecomposer, say scientists behind the innovation that was developed as an answer to stubble burning, a practice linked to the surge in air pollution in the Delhi-NCR region.
The researchers, based at the ICAR-Indian Agricultural Research Institute (IARI) in New Delhi, also noted that proper implementation of the decomposer will not only aid in effective stubble disposal but also contribute to retaining soil fertility.
The PUSA bio-decomposer was developed as an answer to the problem of farmers resorting to stubble burning in Punjab and Haryana in order to quickly clear their fields for another harvest.
Stubble burning has been linked to a spike in air pollution levels in the neighbouring states, including Delhi-NCR, deteriorating air quality in these areas.
November this year saw the Air Quality Index (AQI) of many areas in the NCR repeatedly breach the 'Severe' and 'Severe Plus' limits of 400 and 450, respectively.
The Pusa biodecomposer is a microbial solution that the scientists say can turn about 70-80 per cent of stubble residues into compost in about 20 days. The solution is a consortium of seven fungal cultures that can degrade diverse horticultural and agricultural residues like paddy straw, soybean trash, millet, and maize residues, in addition to vegetable, citrus fruit and flower waste, according to the agricultural research institute.
"Actually, it is the microbes. All we are doing is increasing the number of microbes that will be camping in the decomposition pit, along with all the stubble," explained Livleen Shukla, Principal Scientist, Division of Microbiology, ICAR-IARI, New Delhi.
The decomposer is available as a pre-mix powder that the farmers can instantly use after mixing with water. They could also instead choose to use the solution form of the decomposer, a litre of which is sufficient for preparing compost from 200 kilograms of farm waste like garbage and paddy waste, according to the instructions printed on the bottle in both English and Hindi.
The instructions to the farmers also include turning or shuffling the mixture of biodecomposer solution and stubble residue after 15, 30 and 60 days.
Further, for in-situ or on-field decomposition, the instructions call for spraying 10 litres of the decomposer for every acre after harvesting and turning the soil using equipment such as a rotavator or harrow, or a reverse plough, in addition to irrigating if needed.
"Unless we follow the standard operating protocol, we will not get the desired success (of disposing stubble harmlessly)," said Shukla.
The biodecomposer can be easily incorporated into the irrigation and field preparation practices, which farmers undertake prior to cultivating the next set of crops following rice harvest, according to Dolamani Amat, Senior Scientist, IARI.
"There is no wastage of time. After harvesting, the stubble can be sprayed with the microbial decomposing solution and the soil turned. Now, it needs to be irrigated in order to give the stubble the time to decompose. "However, this time is needed to prepare the field for cultivating crops again. So, the decomposer can fit in well with the irrigation and cultivation timeline of the farmers," said Amat.
Further, research undertaken by scientists at IARI, along with other institutes, has found that the Pusa bio-decomposer can contribute towards improving the yield of wheat by enhancing the fertility of the soil.
"It might be due to improved fertility with incorporation of rice residue and better decomposition of straw with Pusa decomposer, which led to improved physical, chemical, and biological conditions available to the succeeding crop, viz. Higher organic carbon, available NPK (Nitrogen-Phosphorous-Potassium), nutrient uptake, microbial activity and better soil structure in the respective plots leading to lesser crop stress," the study authors, including Shukla, said. Their research was published in the Indian Journal of Agricultural Sciences in February 2023.