Crop Residue Burning and Its Ecological Impacts

Crop residue burning has impacts beyond pollution — study finds disruption in microbial biodiversity, increased pests and fertiliser use

Context: A study in the journal Science of the Total Environment finds that crop residue burning depletes soil nutrients, reducing long-term productivity, while the resulting air pollution disrupts the ecological roles of arthropods and birds.

What is a crop residue?

Crop residue refers to the leftover plant material (straw, stalks, husks, leaves, etc.) that remains in fields after the harvest of crops such as rice, wheat, maize, sugarcane, and cotton. Two types:

Field residues: Remain on the soil surface after harvest (e.g., rice stubble, wheat straw).
Process residues: Generated during crop processing (e.g., husks, bagasse).

In India, large volumes of paddy stubble are burnt in Punjab, Haryana, and western Uttar Pradesh to quickly clear fields for the wheat-sowing season.

What are the major impacts of crop residue?

Air Pollution: Emits PM2.5, PM10, CO, NOx, SOx, methane, VOCs and GHGs → major contributor to Delhi-NCR smog. Health impacts: respiratory diseases, cardiovascular stress, reduced visibility causing accidents.
Soil Degradation: Burning raises soil temp to 33–42°C, kills beneficial microbes up to 2.5 cm depth. Leads to loss of soil organic carbon (SOC), nitrogen, phosphorus, potassium. Long-term decline in soil fertility → higher dependence on chemical fertilisers.
Biodiversity Loss: Study shows sharp decline in arthropods (ladybird beetles, spiders, predatory mites, millipedes, earthworms). Loss of natural pest control, pollination, nutrient cycling, soil aeration. Bird populations suffer indirectly due to air pollution, habitat loss, and decline in insect prey → affects breeding success. Food web disruption across multiple trophic levels.
Agricultural Productivity: Pest outbreaks rise due to loss of natural predators → more reliance on pesticides. Decline in soil health reduces yields in the long term.
Climate Change: Contributes black carbon and GHG emissions, worsening regional climate change. Black carbon deposition accelerates Himalayan glacier melt.

What efforts are required to address the issue of crop residue?

Policy & Legal Measures: Government measures to tackle stubble burning include the Promotion of Agricultural Mechanisation for In-Situ Management of Crop Residue, the GOBARdhan Scheme for waste-to-energy conversion, and subsidies for eco-friendly equipment and crop diversification to reduce residue generation.
Technological Alternatives:
- In-situ management: Happy Seeder, Super Seeder, mulchers, rotavators → sowing wheat directly into standing stubble.
- Ex-situ uses: Biomass-based power plants, ethanol (2G biofuels), compressed biogas (SATAT scheme). Industrial use (packaging, boards, paper pulp, biochar).
- Microbial solutions: PUSA Bio-Decomposer (ICAR-IARI innovation) → decomposes stubble into manure in 15–20 days.
Incentives for Farmers: MSP-linked incentives for stubble management. Carbon credit mechanisms for farmers adopting sustainable practices. Support for crop diversification (shift from paddy to maize, pulses, millets in Punjab-Haryana).
Awareness & Community Engagement: Training, farmer cooperatives, FPOs for machinery sharing. Behavioural change campaigns linking residue management with soil health and long-term income.