Effect of phosphorus sources and levels on Bt-cotton (Gossypium hirsutum) based intercropping systems

A field experiment was conducted during kharif of 2007 and 2008 at New Delhi to assess the performance of intercropped Bt cotton as influenced by P nutrition. The experiment was laid out in split plot design. Five cropping systems viz., sole cotton (Gossypium hirsutum L.); sole groundnut (Arachis hypogaea L.); sole soybean [Glycine max (L.) Merr.]; cotton + groundnut; and cotton + soybean were taken in the main plots and two combination of P sources and biofertilizers viz., single superphosphate and rock phosphate + phosphate solubilising bacteria (PSB) + vesicular-arbuscular mycorrhiza (AM) and two P levels viz., 17.5 and 35 kg/ha including control in the sub- plots. Cotton + groundnut cropping system gave the highest cotton equivalent yield (CEY) of 2.4 t/ha, followed by cotton + soybean system (2.2 t/ha) and sole cotton (2.1 t/ha). Application of 35 kg P/ha recorded on an average 14.2% higher CEY over 17.5 kg P/ha. Cotton + groundnut system recorded an additional mean net returns of 6,512 compared to sole cotton (39,382/ha). Application of 35 kg P/ha increased the mean net income to the tune of 5,604/ha over 17.5 kg P/ha with a mean B:C ratio of 1.8. Quality traits of cotton remained unaffected by cotton intercropping.