Phosphate Manuring of Soybean and its Effect on Wheat Yield

Phosphate manuring of soybean not only increased the yields of soybean in well drained alluvial soils, but also increased the nitrogen status of the soil. The nitrogen contents in the soil after growing soybean manured with phosphate was much higher (0.100%) than that in unmanured plots (0.0861%). This increased the yields of wheat taken in sequence. This response to phosphate manuring of soybean on wheat was as high as 6–8 kg of grains per kg of P₂O₅ applied per hectare to previous crops of soybean in 1969–70 and 1970–71. At a high dose of phosphate manuring (160 kg P₂O₅/ha), the growth of soybean was impaired and so was the yield of wheat. The best response on wheat was obtained when soybean was manured with 80 kg P₂O₅/ha).