Productivity and soil fertility changes under continuous fertilization of rice (Oryza sativa) -rice cropping system

Abstract

A long-term experiment in an Udic Ustochrepts soil with rice (Oryza sativa L.) -rice cropping system was conducted during 1987-96 at Hyderabad to evaluate the effect of continuous cropping and fertilization on yield and soil fertility.
Maximum doses of fertilizer @ N₁₂₀ and P₈₀ had increased grain yield by about 0.6 to 0.7 tonne more compared to N₄₀ no P₂ 0₅ Potash application @ K₄₀ kg/ha showed a meagre response. Net returns for the cropping system were maximum (Rs 13 180/ha) at N₁₂₀ P_8O K₄₀' Stability analysis of grain yield indicated that consistent productivity is possible with N₈₀ P₄₀ K₀ both in rainy season (kharif) and winter season (rabi). After 10 consecutive years of cropping, available phosphorus and Potassium got depleted compared to their initial status. Available iron, zinc,pore space, water holding capacity and volume expansion showed increase over their initial values after 20 seasons of cropping. The trends clearly emphasised the need for balanced fertilization of rice for consistent productivity.