Rice residue management in the Indo-Gangetic Plains for climate and food security. A review

Abstract This paper reviews and analyzes the impact of residue burning on the environment and human health, and the influence of ex-situ and in-situ residue management on reducing pollution and improving soil health, crop yield, and farmers’ economic benefits. Paddy is cultivated on 43.8 Mha in India, producing 118.43 Mt grain and an estimated 165.8 Mt straw. Burning is the most common practice for managing rice crop residues mainly due to its simplicity, low cost, increased mechanical harvesting, short window between rice harvest and wheat sowing, and lack of viable uses for residues. Around 50 Mt of rice straw is burned annually, nearly half of which occurs in northwestern India during October/November. Burning residue is a major contributor to air pollution, emitting around 1.5 Mt particulate matter, 150 Mt carbon dioxide, and other greenhouse gases (e.g., NO 2 , SO 2 , CO, CH 4 , NH 3 ) and volatile organic compounds, resulting in a wide range of respiratory infections in humans, reduced soil nutrient and carbon inputs, and disturbed soil microbial activity. In-situ residue management using a Happy Seeder, Super straw management system, paddy straw chopper cum spreader, reversible moldboard plow, or no-till seeder incorporates or mulches residues, avoiding burnings. These operations are economically profitable as they reduce costs, increase yields, or both. In-situ residue management, i.e., incorporation or mulching improves the soil’s physical, chemical and biological properties and is considered better for improving soil health than residue removal. Ex-situ residue management for biofuel, biochar, electricity generation or bale making is also profitable for the environment and reduces pollutant emissions.