Crop residues (rice and wheat straw, cane trash) managed by in-situ incorporation with microbial decomposers, mulching and collection for biogas/bio-CNG instead of open-field burning

Replaces: open-field residue burning · Scope: rice–wheat, sugarcane, cereals · Evidence: high (harm, mechanical and ex-situ options), low–medium (decomposer sprays)

The chemical problem#

• North-west India burns millions of tonnes of rice straw every October–November to clear fields for wheat; the smoke is a major driver of Delhi’s winter air pollution.
• Burning releases PM2.5, black carbon and polyaromatic hydrocarbons, and destroys nitrogen, sulfur and organic carbon that the next crop needs.
• Pre-harvest cane burning and stubble burning happen across South and Southeast Asia, Africa and Latin America.

Product overview#

1. In-situ management — happy seeder / super seeder sow wheat directly into rice stubble (straw stays as mulch); mulchers and incorporation tillage.
2. Microbial decomposers — fungal/bacterial consortia (e.g. Trichoderma, Aspergillus, cellulolytic bacteria) sprayed on straw to speed decomposition (India’s public “Pusa decomposer” and commercial products).
3. Ex-situ use — baling straw for bio-CNG/biogas, power plants, pellets, fibre boards and packaging.
4. Pyrolysis to biochar — small kilns that turn residues into a soil amendment instead of smoke.

Active ingredient / Composition#

• Decomposer consortia: cellulolytic and lignolytic fungi and bacteria, sold as capsules, powders or liquid concentrates; applied at a few litres of prepared culture per hectare with water.
• Ex-situ: straw bales as feedstock (rice straw ~1.5–2 t/ha dry matter per t grain).

Key facts#

Advantages#

• Ends a seasonal public-health crisis while keeping N, S and carbon in the soil.
• Mulch conserves water and suppresses weeds in the following wheat.
• Ex-situ routes create rural income from a residue (bio-CNG, pellets, board).
• Biochar and incorporation add stable carbon (carbon-credit potential).

Mode of action#

• Mulch and incorporation return lignocellulose to soil; soil microbes mineralize it over the following season.
• Decomposer cultures add cellulases and ligninases to start breakdown faster — useful if moisture and temperature allow.
• Anaerobic digestion converts straw carbohydrates to methane; digestate returns nutrients (see NU03).

Application#

Limitations#

• Machines need capital and custom-hiring services; small farms depend on subsidies.
• Decomposer sprays: evidence is weaker than the marketing — independent trials should precede large-scale promotion.
• Straw logistics (baling, transport, storage) are costly and seasonal.
• Mulch can raise pest or N immobilization issues at first.

Evidence of displacement — D2: measurable displacement (minority share)#

Assessment (hand-reviewed): Punjab crop-residue burning down 87% (2020–2024) — burning fell; the microbial share of the replacement is not shown.

Figures found (verified as quoted, but the assessment above explains why they do not count as displacement evidence for this substitution):

• displacement — In Punjab, residue burning events decreased by 87% in 2024 relative to the 2020 baseline of 83,002 events. (Punjab, India, 2020-2024; government or intergovernmental: epubs.icar.org.in)
• displacement — In specific intervention areas, the share of burning as a predominant crop residue management method has decreased from approximately 90% in 2018 to 50% in recent years, with some areas achieving less than 5% burning. (Punjab and Haryana, India, 2018-2024; weak: sustainabledevelopment.in)
• displacement — The share of paddy straw managed without burning in Punjab increased from 20.49% in 2016 to 49.91% in 2023. (Punjab, India, 2016-2023; weak: acspublisher.com)
• displacement — In a 2022 survey of Punjab farmers, 58% used in-situ crop residue management practices, while 33% opted for ex-situ methods. (Punjab, India, 2022; weak: ceew.in)

Suppliers — real products and services (from the vendor index)#

Active vendors whose own card shows a residue-management, decomposer or residue-to-energy product.

Government funding signals#

Scanned 2026-10-01 (OpenAIRE + NSF); candidates reviewed by hand.

Signal: Weak (USDA; added 2026-10-02). The USDA source adds US rice-residue work — NIFA 20226701936102 (water and residue management approaches, $0.75 M, 2022) and 20216702134493 (uses of crop residues, $0.44 M) — but the burning problem itself is funded by national programmes in South Asia. Earlier note: The query “crop residue burning” returned only unrelated awards. Public money for this problem comes from national programmes (India’s crop-residue-management machinery scheme, state bio-CNG incentives, China’s straw-utilization subsidies), which these sources do not index.

Scientific evidence#

• Jain N, Bhatia A, Pathak H (2014). Emission of air pollutants from crop residue burning in India. Aerosol and Air Quality Research 14: 422–430.
• Bhuvaneshwari S, Hettiarachchi H, Meegoda JN (2019). Crop residue burning in India: policy challenges and potential solutions. International Journal of Environmental Research and Public Health 16: 832.
• Shyamsundar P, Springer NP, Tallis H, et al. (2019). Fields on fire: alternatives to crop residue burning in India. Science 365: 536–538.

Bioeconomy value#

Hundreds of millions of tonnes of straw per year are either a pollution problem or a feedstock. Bio-CNG, board, pellets and soil carbon pay farmers to stop burning, and the plant builders and decomposer makers are already in this index.