Response of pigeonpea (Cajanus cajan) to sources and levels of phosphorus under rainfed condition

Abstract

A field experiment was conducted during rainy seasons of 1999 and 2000 to study the effect of sources and levels of phosphorus on productivity of pigeonpea [Cajanus cajan (L.) Millsp.]. Application of single superphos- phate (SSP) produced significantly higher noduleslplant, dry weight of noduleslplant and pods/plant than that of diammonium phosphate (DAP). Application of SSP increased the seed yield, total P uptake and net returns over their respective DAP respectively by &I%, 0.53 kg P,O,/ha and R s 9131ha. Phosphorus application increased the noduleslplant, dry weight of noduleslplant, podslplant, seed yield, total P uptake and net returns significantly. Seed y~eld and net returns increased slgnlficantly with P levels up to 40 kg P,O,/ha, giving 52.4 and 18.3 % and Rs 6,757 and Rs 3,002lha more over the control and 20 kg P,O, respectively. ReturnsIRe invested was recorded more under 60 and 80 kg P,OJha (Rs 2.76), followed by 40 kg P,O,/ha (Rs 2.66). The agronomic P-use effi- ciency (APUE) and apparent P recovery were higher in SSP; however, these were recorded more at lower level of P and decreased with increase in P level. The physiological efficiency of phosphorus (PEP) and phosphorus- use efficiency (PUE) were calculated more in DAP. However, PEP increased with increase in P level.