Influence of Long-Term Nitrogen Substitution through Organics on Yield, Uptake and Available Nutrients in a Rice-Wheat System in an Acidic Soil

Effect of nitrogen substitution through different organics on yield, uptake and available nutrients in a ricewheat system was studied after 17 and 18^th cropping cycles. Nitrogen substitution through different organics increased significantly the productivity and NPK uptake by rice and wheat. Grain yield of rice, wheat and that of the system increased significantly with the increasing levels of NPK. The maximum yield of rice (3.62 t ha⁻¹) and that of the system (7.04 t ha⁻¹ in terms of rice grain equivalent) was recorded under T₅ (50% NPK along with 50% N through FYM during kharif followed by 100% NPK during rabi), while wheat grain yield was maximum (3.20 t ha⁻¹) in T₄ (100% NPK to both the crops). The total uptake of N, P and K by rice-wheat system was also highest in T₅. Though the chemical sources of nutrients increased crop yields over control, these failed to improve the soil properties vis-a-vis combined use of the organics and inorganics. The improvement of soil fertility with respect to available macronutrients and micronutrient cations was also prominent with the application of 50% NPK + 50% N through FYM in kharif followed by 100% NPK in rabi.