Productivity and sustainability of cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum L.) cropping system as influenced by prilled urea, farmyard manure and Azotobacter

Field experiments were conducted at Indian Agricultural Research Institute, New Delhi, during 2001-2002 and 2002-2003, to study the effect of inorganic, organic and Azotobacter combined sources of N on cotton (Gossypium hirsutum L.) and their residual effect on succeeding wheat (Triticum aestivum L.) crop. The results indicated considerable increase in yield attributes and mean seed cotton yield (2.33 Mg ha(-1)) with the combined application of 30 kg N and farmyard manure (FYM) at 12 Mg ha(-1) along with Azotobacter (M-4). The treatment in cotton that included FYM, especially when fertilizer N was also applied could either improve or maintain the soil fertility status in terms of available N, P and K. Distinct increase in yield attributes and grain yield of wheat was observed with the residual effect of integrated application of 30 kg N ha(-1) + FYM at 12 Mg ha(-1) + Azotobacter. Direct application of 120 kg N ha(-1) resulted 67.4 and 17.7 % increase in mean grain yield of wheat over no N and 60 kg N ha(-1), respectively. Integrated application of organic and inorganic fertilizer is therefore, recommended for higher productivity and sustainability of the cotton-wheat system.