Economic and environmental effects of practicing crop residue on-field composting as a substitute for burning – a case study of Punjab (India)

Crop residue burning, a prevalent and urgent issue in India, particularly in the IndoGangetic Plains of Haryana, Uttar Pradesh, and Punjab states, has detrimental effects on the climate of the region, agricultural production, and the health of humans, animals, and plants. Despite legal and technological barriers to crop residue burning and the availability of profitable alternatives for farmers, this practice persists in Punjab state. The primary reasons for the ongoing crop residue burning practice are, the amount of surplus crop residue generated, the time constraints of the rice-wheat crop rotation, and the height of stubble left in the field after the mechanical harvesting of rice and wheat crops. One of the proposed alternatives, the incorporation of crop residues directly into the soil before planting the next crop, is considered best. However, this practice is not accepted by farmers of Punjab on a large scale, as it generally decreases crop yields due to Nitrogen (N) immobilization. To counter this constraint, a modified method of incorporation, on-field composting is proposed to manage the rice and wheat crop residues in Punjab. In this method, crop residues will be collected on the field and composted in an on-field composting pit. A valuable product – compost is formed which is broadcasted in the field as an organic fertilizer. This study includes a theoretical analysis of the on-field composting method to manage rice and wheat crop residues. Firstly, crop residue on-field composting costs are assessed and compared with crop residue burning costs to give farmers of Punjab an idea of cost savings by composting crop residues on the field. For this, various input and output costs of the burning method and onfield composting method are evaluated and compared on a per acre basis for managing rice and wheat crop rotation based residues in all districts of Punjab based on the data for three consecutive years (2020, 2021, and 2022). For all three years, in most of the districts of Punjab, the burning practices-related costs per acre were found to be higher than on-field composting costs per acre only if a crop residue burning penalty imposed on a farmer is added as an input cost to the Net Burning Costs per acre. However, without adding crop residue burning penalty cost, the on-field composting costs per acre are higher as the chances of imposing penalties on every farmer who burns crop residues are quite low. Secondly, in this study, the variation of input costs of the on-field composting process, such as labor and machinery costs, along with variation in landholding size (number of acres) with farmers, is also analyzed. For this, four onfield composting models (one-acre, four-acre, eight-acre and sixteen-acre) are studied keeping in mind farmer’s land-holding categories in Punjab. The input cost (labor and machinery costs) per acre for each on-field composting model varies depending on the size of the farmland (number of acres) in each district. In addition, GHG emissions and the social cost of these emissions on crop residue burning are studied as compared to on-field composting of crop residues. As per our assessment, the on-field composting method for managing crop residues is better for both the farmers and the environment of Punjab. The practical implication of this study could be a future research project.