Effect of phosphorus and gypsum on growth of pearl-millet in sodic soils

A screen-house experiment was conducted to investigate the effect of P and gypsum application on availability of P to pearl-millet on two sodic soils (ESP 30.2 and 54.9). The treatments consisted of combinations of four levels of P (0, 30, 60 and 90 mg P kg⁻¹ soil) and three levels of gypsum (0, 25 and 50% of GR). The crop was harvested at ear initiation stage. The depression in plant growth due to sodicity was more severe at lower levels of P, and P application nullified hazardous effects of sodicity. Plants grown on soils of high sodicity needed higher dose of P application inspite of more available P content in soils. The dry matter yield, P uptake and fertilizer use efficiency decreased with increasing sodicity but increased with gypsum application. Shoot P concentration, post-harvest available P in soil and per cent recovery of added P into available P increased with increasing P levels and sodicity and decreased with gypsum application. The increase in dry matter yield with unit increase in shoot P concentration was consistently lower at higher sodicity. The pH of the soils remained unchanged due to P application but decreased with gypsum application.