Abstract:
Microbial Remediation of Crop Residues (CRs) is defined as the use of selected consortia of efficient synergistic microorganisms for managing CRs within a short duration of time by hastening the degradation process. It is emerging as one of the efficient approaches for managing paddy straw, wheat straw, maize/ corn stalks and sugarcane trash with naturally enriching the soil and reducing the need for chemical fertilizers, suppressing the soil borne pathogens, agricultural sustainability, and eliminating the need to stubble burning, a matter of great concern to environmental pollution, human health, soil health, and global warming.
The major crops grown for food and other consumable products include cereals (58.32%), fibre (19.72%), oil seeds (4.63%) and sugarcane (17.33%). Crop Residues (CRs) is a term used for the plant parts left in the field after harvesting the economic part of an agricultural crop. Globally, 3-4 billion tons of CRs, including rice husks, wheat straw, sugarcane bagasse, and corn stalks, wheat and rice dominating, are generated annually. India generates around 350 million tons of agricultural waste each year (PIB 2026). Market data reveals that currently nearly 54% of global crop residues are recycled/ used through composting, biogas and biofuel production and remaining burned in open fields, causing huge economic losses. The global agricultural waste market size is worth USD 21.57 billion (in 2026) which is projected to reach 40342.05 million dollars by 2035 at a CACR of 7.2% between 2026 and 2035.
Micro-remediation Technology has proven as the novel solution to open – field on site burning millions of tons of crop residues, providing protection from the environmental pollutants, improving soil fertility, protecting beneficial soil microbiota essential to nutrient cycling, and global warming, a major concern of 21st century. In this technology, inoculum of selected efficient microbial consortia, of bacteria, fungi or both type of microorganisms, are inoculated in situ (at the straw production sites, i.e., agricultural fields) or ex situ (at another site, i.e., compost pits). The major microorganisms used are the fungal taxa Trichoderma and Aspergillus and the bacterial taxa Bacillus and Pseudomonas. These microbes have the ability to degrade tough lignocellulosic plant constituents at a fast rate as they possessed lignocellulolytic enzymes like cellulases, ligninases and hemicellulases converting the biomass into simple molecules to be used by microorganisms for their growth and as an organic fertilizer by plants.
In India, 80% parali (paddy straw and stubble) of the total 170 million tons produced in the year 2024 was burned in open fields. To-overcome the burning nuisance (environmental pollution, atmospheric brown cloud formation impacting the vehicle's mobility, AQI), depletion of soil nutrients moisture and microbiota and promoting to organic farming, 4 bio-decomposer products are currently used in India. Pusa Decomposer, developed in 2020 by the IARI, New Delhi, based upon 7 fungi, having the potential to degrade diverse horticultural and vegetable waste. In fields, it decomposes paddy straw within 20 days in fields making the next crop ready for cultivation, significantly reducing the 116 million tons of crop residues burned annually. It is commercially being sold in the form of capsules by 17 Indian companies. 2nd product is Trichoderma based organo-decomposer, developed by UPCSR, based upon the fungus T. harzianum (which acts both a bio-fungicide and biofertilizer), converts paddy straw into compost within 10 days. 3rt product is Bajrang Baan, a microbial consortium, manufactured by Marino company, converts paddy straw into compost in 21day under ex situ conditions. 4th product Orgogrowth Bio Decomposer, is based upon a mixture of fungi and bacteria (Trichoderma viride, Aspergillus niger and Bacillus subtilis) with the ability to convert paddy straw into compost in 21-30 days and is used both in situ and ex situ conditions.
Future researches are needed reduce the degradation times of the CR like paddy straw and sugarcane bagasse to 2-3 days and the field to be ready for the successive crop’s cultivation, an obstacle in accepting this technology by farmers. This can be achieved if the scientists search lignocellulolytic enzymes and by adding them to the microbial consortium for accelerating the decomposition process, fulfilling the need of organic farming and agriculture sustainability.