Abstract

Response of intercropping system, inorganic fertilizers, biofertilizers, intercrop residues and leaf extract spray on post harvest soil nutrient status of irrigated cotton were evaluated by conducting field experiments at Agricultural College and Research Institute, Madurai during summer 2006 and winter 2006-2007. The experiments were laid out in a split plot design with three replications. Intercropping system viz., C1 – Cotton sole, C2 – Cotton + Blackgram, C3 – Cotton + Greengram and C4 – Cotton + Cluster bean were allotted to mainplot. The intercrops residues were incorporated at 65 DAS. The subplot consisted of six nutrient management and botanicals spray treatments viz., N1 – 100 % RDF (Recommended Dose of fertilizer – 80:40:40 kg NPK/ha), N2 – 75 % RDF, N3 - 75 % RDF + biofertilizers, N4 -75 % RDF + 5 % Morinda leaf extract spray at 60 and 80 DAS, N5 - 75 % RDF + 5 % Vilvam leaf extract spray at 60 and 80 DAS, N6 - 75 % RDF + 5 % Annona leaf extract spray at 60 and 80 DAS. The biofertilizers include azospirillum + Phosphobacteria + Silicate solubilizing bacteria each at 2.6 kg/ha. The results reveal that cotton + blackgram intercropping with application of 75 % RDF + combined application of azospirillum, phosphobacteria and silica solubilizing bacteria recorded higher soil available nitrogen and phosphorus content.

Keywords: Intercropping, nutrient management, biofertilizers, leaf extract spray