Cotton Stalk Compost as a Substitution to Farmyard Manure Along with Mineral Fertilizers and Microbials Enhanced Bt Cotton Productivity and Fibre Quality in Rainfed Vertisols

Cotton stalks, remaining after the cotton is harvested, are considered waste material and disposed of by burning. Presently, the supply of good quality manure, such as farmyard manure (FYM) is low. Thus, recycling of cotton stalks as compost can reduce the dependency on FYM apart from reducing inorganic fertilizer use and soil health enhancement. Some studies have reported on the conversion of cotton ginnery wastes into organic manure. However, no studies have reported about the composting of cotton stalks. We conducted field studies over three years on Vertisols to evaluate the impact of integrated use of microbially enriched cotton stalk compost (ECC) as an alternative to FYM along with mineral fertilizers in cotton production. Additionally, we evaluated an option of using native microbial consortia as seed treatment and studied their synergistic effect along with ECC application on cotton yield, fibre quality, and soil properties. Results indicated that the substitution of FYM with ECC in integrated nutrient management (INM) produced effects similar to that of FYM use in enhancing cotton yield, fibre quality and soil properties. Application of ECC + inorganic fertilizers (referred as modified nutrient management practice-MINM) increased boll numbers (8.4%) and boll weight (9.9%) compared to the recommended dose of fertilizers (RDF). Treating cotton seeds with microbial consortia increased seed cotton yield (SCY) by 12.8% (2815 kg ha(-1)) compared to untreated seed plot (2496 kg ha(-1)). Averaged over the years, INM (3344 kg ha(-1)) followed by MINM (3190 kg ha(-1)) recorded significantly higher SCY than RDF (2835 kg ha(-1)), which were 18 and 13% more than the RDF, respectively. MINM practice enhanced cotton fibre properties (staple length and bundle strength), soil nutrient status (major, secondary and micronutrients), and biological activities (microbial biomass carbon and soil enzymes), which were on par with INM. The use of ECC in INM is estimated to reduce 33% costs on nitrogenous, phosphatic, and potassic fertilizers, and can save approximately US$ 38 ha(-1) on inorganic fertilizers and manures in the recommended dose of fertilizers (RDF) and INM practice. [GRAPHICS] .

Automated summary

Composting cotton stalks can reduce dependency on farmyard manure, decrease inorganic fertilizer use, enhance soil health, and have similar effects on cotton yield, fiber quality, and soil properties as farmyard manure.