Effect of multinutrient briquette on soil NPK availability, microbial population and dehydrogenase activity under rainfed Bt cotton

Abstract:

A field investigation was undertaken during kharif season of 2025-26 at EAD Farm, College of Agriculture, Nagpur in Randomised Block Design with seven treatments. The treatment comprised following levels of organic fertilizers, inorganic fertilizers and micronutrients viz., T₁- 100% NPK + micronutrient (50%N, 100%P,K, micronutrients at sowing and 50% N at 30-35 DAS), T₂- 100% RDF through MNB at sowing, T₃- 100% RDF through MNB (50% at sowing and 50% at 30-35 DAS), T4- 75% RDF through MNB (50% at sowing and 25% at 30-35 DAS), T₅- 100% RDF through MNB (50% at sowing and 25% at 30-35 DAS and 25% at 50-55 DAS), T₆- 75% RDF through MNB (25% at sowing, 25% at 30-35 DAS and 25% at 50-55 DAS) and T₇- Absolute control. The results of the present study revealed that, the available nitrogen content in soil ranged between 193.52 to 209.74 kg ha^-1. The highest nitrogen availability was noted under T₃ (100% RDF through MNB in 2 splits). Available phosphorus content was observed between 20.18 to 24.22 kg ha^-1. Available potassium showed significant variation, with the highest value of 343.6 kg ha^-1 under 100% NPK + micronutrients, followed closely by 339.3 kg ha^-1, 337.3 kg ha^-1 and 332.7 kg ha^-1 under treatment T₃, T₂ and T₅ respectively. Microbial population of bacteria, fungi and actinomycetes at vegetative stage of cotton shows variation as influenced by application of multinutrient briquette. The significant increase in bacteria, fungi and actinomycetes was observed with the addition of 100% RDF through MNB and inorganic fertilizers with micronutrients. The dehydrogenase activity observed maximum with increased dose of inorganic fertilizers with organic source.