Efficacy of utilization of applied P by cereal and legume crops in sequence

A field experiment was conducted for two years on Typic Ustochrepts soil to study the residual effect of P applied by broadcast and deep placement at four rates (0, 13, 26, 39 kg P/ha) to wheat on succeeding crops of cowpea, maize and lentil. Soil was maintained at three moisture regimes (0.6, 0.8, 1.0; IW/PAN-E ratio) during wheat and at 0.8, 1.0, 1.2 IW/PAN-E ratio during cowpea crop growth. Grain yield and P removal by wheat increased significantly upto 39 kg P/ha and also with placement of P fertilizer. Increase in irrigation (0.6 to 1.0 IW/PAN-E ratio) significantly increased grain yield and P removal by wheat. Dry matter production and total P removal by cowpea increased significantly upto an applied rate of 13 and 39 kgP/ha to wheat, respectively. Dry matter and toial P removal also increased significantly with increase in irrigation (IW/PAN-E Ratio 0.8 to 1.2). The grain yield of maize, however, did not increase significantly with p applied to wheat, whereas, the grain yield of lentil. The fourth crop in sequence increased significantly upto an applied rate of 39 kg P/ha to wheat. The effect of plaement of fertilizer P was significant upto second crop (cowpea) in the sequence. The fertilizer p use elleciency decreased both with rate of P and cropping. The third (maize) and fourth (lentil) crops removed only 6–7% the of applied P. More than 50% of applied P was recovered in four crops viz Wheat, cowpea (fodder), maize and lentil.