Rice productivity and soil fertility as influenced by nutrient management in rice (Oryza sativa)–wheat (Triticum aestivum) cropping system

A field experiment was conducted during the rainy (kharif) seasons of 2010 and 2011 at Pantnagar, Uttarakhand, to evaluate the effect of nutrient management on rice (Oryza sativa L.) productivity, nutrient uptake and soil fertility under long–term rice–wheat (Triticum aestivum (L.) emend Fiori & Paol] cropping system. Twelve treatments, viz. control,N₁₂₀, N₁₂₀ P₄₀, N₁₂₀ K₄₀, P₄₀ K₄₀, N₁₂₀ P₄₀ K₄₀, N₁₂₀ P₄₀ K₄₀ + Znf (@ 0.5%), N₁₂₀P₄₀K₄₀+ FYM (@ 5 tonnes/ha), N₁₂₀ P₄₀ K₄₀+ Znf + FYM, N₁₈₀P₈₀+ Znf, N₁₈₀ P₈₀ K₄₀+ Znf and N₁₈₀ P₈₀ K₄₀+ Znf + FYM, were maintained in a fixed layout right from the beginning of the experiment (1984–85) in a randomized block design with 4 replications. Combined application of NPK, FYM and Zn (N₁₂₀ P₄₀ K₄₀ + Znf + FYM) significantly increased the grain yield (6.22 tonnes/ha) of rice over all the other treatments except N₁₂₀ P₄₀ K₄₀ + FYM (6.20 tonnes/ha) and N₁₈₀ P₈₀ K₄₀ + Znf + FYM (6.19 tonnes/ha). The treatment N₁₈₀ P₈₀ K₄₀ + Znf + FYM recorded the highest soil available nitrogen and phosphorus (229.5 kg/ha and 25.1 kg/ha), which was significantly at par with N₁₂₀ P₄₀ K₄₀ + FYM (225.3 kg/ha and 24.6 kg/ha) and N₁₂₀ P₄₀ K₄₀ + Znf + FYM (223.9 kg/ha and 24.8 kg/ha). The available soil potassium content was low to medium in range (183.1–220.0 kg/ha). The FYM application improved the rice yield and sustained soil fertility. Soil organic matter content reported in 1984 (2.1%) was found maintained in FYM containing treatments (2.15–2.17%), while declining with inorganic treatments. The uptake of N, P and K was found to be associated with production of total dry matter resulted by the addition of NPK fertilizer and FYM application.