Influence of integrated nutrient management on nitrogen and phosphorus in soil under wheat-mungbean-maize cropping system

An investigation was carried out to assess the influence of integrated nutrient management on dynamics of nitrogen (N) and phosphorus (P) in soil under a wheat-mungbean-maize cropping system. Eight treatments viz. fertilizers applied at 50, 75 and 100% of the recommended dose (N₁₂₀P₆₀K₆₀), N₁₂₀ only, P₆₀ only, FYM (@ 5 t ha⁻¹) applied alone, and in combination with 50 and 75% recommended NPK were applied to wheat. These treatments were compared with no-fertilizer and manure control. Mungbean was grown following wheat without any fertilizer or manure application. It was allowed to grow till maturity, and after two pickings, the stover was incorporated into the soil. Zero, 50 and 75% of the recommended dose of fertilizer (N₁₂₀P₆₀K₆₀) were applied to maize. The treatments where higher amounts of fertilizer-N were added, registered higher contents of ammoniacal, nitrate and alkaline KMnO₄ oxidisable (available) N in the soil. Similarly, higher doses of fertilizer-P resulted in higher values of Olsen-P and total inorganic P. Application of FYM @ 5 t ha⁻¹ along with inorganic N was found to maintain the levels of all these forms of soil N up to maize harvest. Inorganic P showed an inverse relationship with the organic P content at all the growth stages of the three crops under study.