Long-term effect of micronutrients and FYM on yield of and nutrient uptake by soybean on a typic chromustert

A long-term (1992–1998) field experiment was conducted on clay loam soil (Typic Chromustert) to study the effect of application of micronutrients (Zn, Mo & B) individually and in combination with FYM on NPK uptake, seed yield of soybean and NPK balance in soil. Combined application of 5 kg Zn and 10 t FYM ha⁻¹ increased grain yield, NPK contents in and uptake by soybean seed. The highest grain yield (1790 kg ha⁻¹) was recorded in Zn + FYM treatment with a record of 18.2 per cent increase over control (1515 kg ha⁻¹) while the application of B+FYM (13.6%) was on par with seed treatment with Na molybdate (13.1%). A major portion of the applied nutrients remained in soil, which significantly increased the seed yield and nutrient uptake by soybean crop. There was positive balance of available N, P₂O₅ and K₂O in soil when soybean fertilized either with FYM alone or along with micronutrients. Seed treatment with Na molybdate + FYM showed highest build up of N (6 kg ha⁻¹), P₂O₅ (3 kg ha⁻¹) and K₂O (7 kg ha⁻¹) at the harvest of soybean.