Site-Specific Nutrient Management under Rice-Based Cropping Systems in Indo- Gangetic Plains: Yield, Profit and Apparent Nutrient Balance

Abstract

High fertilizer use efficiency in rice (Oryza sativa L.)-based cropping systems in Indo-Gangetic Plains (IGP) is not achieved because farmers’ fertilizer practices (FFP) and blanket state recommendations (BSR) do not take into account the site-specific variability of nutrient availability in the soil. We evaluated the site-specific nutrient management (SSNM) option against existing FFP, blanket state recommendation (BSR), improved BSR (IBSR i.e., 25 % higher than BSR), and state soil testing laboratory recommendation (STLR) in six pre-dominant rice-based cropping systems namely wheat–rice (W–R), mustard–rice (M–R), potato–rice (P–R), garlic–rice (G–R), chickpea–rice (C–R) and berseem fodder–rice (B–R) in terms of yield gain, economics, nutrient harvest index, soil fertility, and apparent nutrient balances. System rice equivalent yield (SREY) improved by 15.7, 9.5, 13.9 and 30 %, in SSNM over BSR, IBSR, STLR and FFP, respectively. SSNM involved additional cost of ` 2940–5291 ha−1 over BSR and ` 5492–10120 ha−1 over FFP under different cropping systems but contributed higher added net return of ` 23236–75056 ha−1 and ` 39577–143899 ha−1 over BSR and FFP, respectively. The output: input ratio and nutrient harvest index for N, P, K were also highest in SSNM. At the end of the experiment, soil available N, Olsen-P and available K content were either maintained or improved over their initial values in SSNM treatments, whereas soil available K in FFP declined by −1.65 % and increased over initial content in BSR and STLR in 0– 15 cm soil profile depth. After three crop cycles, apparent N and P balances were positive in all the cropping systems and fertilizer treatments; only exception was a negative N balance in C–R and B–R systems in different fertilizer treatments. The apparent K balances were negative in all the cropping systems irrespective of nutrient management options. But, the magnitude of negative balance was lower in plots received SSNM treatment as compared to other nutrient management strategies, indicating a potential for improving yields, nutrient use efficiency and farm profit without deteriorating soil fertility in different rice based systems in IGP.