Uptake of NPK, Availability of NPK and Quality Parameters of Bt Cotton (Gossypium hirsutumL.) as Influenced by Different Bio-fertilizers andIn-situGreen Manuring under Irrigation

A field experiment was carried out during kharif season of 2009–2010 at the Agriculture College Farm, Raichur, Karnataka (India) to study the response of Bt cotton to different fertilizer levels, bio-fertilizers and in-situ green manuring under irrigation. With respect to uptake and availability of NPK, application of sunnhemp in-situ green manuring found significantly higher N (128.27 kg ha−1 and 206.43 kg ha−1, respectively), P (30.63 kg ha−1 and 38.43 kg ha−1, respectively) and K (142.33 kg ha−1 and 342.14 kg ha−1, respectively) over no green manuring. Among different fertilizer levels and bio-fertilizers, 150% recommended dose of fertilizers (RDF) recorded significantly higher uptake and availability of N (132.46 kg ha−1 and 212.48 kg ha−1, respectively), P (32.44 kg ha−1 and 39.21 kg ha−1, respectively) and K (147.21 kg ha−1 and 353.29 kg ha−1, respectively). Significantly higher ginning percentage and lint index were observed with sunnhemp in-situ green manuring (35.81 and 4.99, respectively) over no green manuring. Mean fibre length of Bt cotton was not significantly influenced by both use of in-situ green manuring and combined use of inorganic nutrients and bio-fertilizers.