Long–term effect of different fertilizer substitution practices on grain yield of rice and wheat and their correlation with soil properties in a Mollisol

Rice-wheat cropping system is a central agricultural production system to meet the increasing food demand. Productivity of rice-wheat cropping system cannot be sustained until and unless the nutrient supply at a desired level is not maintained. Generally, yields in the long-term experiments remained stable when recommended doses of N, P and K were applied Though, use of chemical fertilizers is the fastest way of replenishing the nutrient depletion, yet ever increasing energy cost, limited input availability and rising fertilizer prices deter the farmers from using these inputs to required level. In order to study the long-term effect of different treatments on crop yield and their correlation with soil properties in a Mollisol, a field experiment was conducted at Norman E. Borlaug Crop Research Centre of the Govind Ballabh Pant University of Agriculture and Technology, Pantnagar during 2014-2015. The partial replacement of N through FYM, wheat straw and mung straw caused significant improvement in soil properties and crop yield. The grain yield of rice and wheat in the year 2014-2015 ranged from 2552.67 to 5700.67, 1850.00 to 4315.67 kgha-1, respectively under different treatments. The grain yield of rice was found maximum T7 (5700.67 kg ha-1) treatment where the recommended dose of fertilizer was substituted to the extent of 25% by FYM, followed by T10 (5625.67 kg ha-1) where 50 percent of N was applied through mung straw along with 50 percent through NPK and T8 (5621.67 kg ha-1) where substituted to the level of 50% by wheat straw. Whereas, the maximum grain yield of wheat was found in T7 (4315.67 kg ha-1) treatment where the recommended dose of fertilizer was substituted to the extent of 25% by FYM, followed by T6 (4292 kg ha-1) treatment where substitution to the level of 50% by FYM and T11 (4130.67 kg ha-1) where substituted to the level of 25% by mung straw. There were significantly negative relationship of rice grain yield with soil pH(r = -0.745**), electrical conductivity (r =-0.641*) and significantly positive relationship with phosphorus (r = 0.903**), sulphur (r = 0.906**) and calcium (r = 0.856**). Whereas, the grain yield of wheat showed significantly negative relationship with pH (r =-0.833**) and significantly positive relationship with phosphorus (r = 0.885**), sulphur (r = 0.866**) and calcium (r = 0.825**). While, other soil properties showed non-significant correlation with rice and grain yield of crops.