Phosphorus use-efficiency of soybean as affected by phosphorus application and inoculation

Abstract

Phosphorus uptake and utilisation by soybean (Glycine max (L.) Merrill) is essential for proper growth, and in ensuring higher yield and improved quality of the crop. To study the effects of inoculation and phosphorus application on soybean nutrition, an experiment was conducted at two locations in the North West Frontier Province (NWFP) of Pakistan. Four levels of P (0, 40, 60, and 80 kg/ha of P 2 O 5) with two levels of inoculation (no inoculation and inoculation with Bradyrhizobium japonicum) were studied in the experiment. Data were recorded on biological yield, seed yield, and P concentration in biological yield. P uptake efficiency (PUPE), P utilisation efficiency (PUTE), P use efficiency (PUE), fertiliser P uptake efficiency (FPUPE), fertiliser P utilisation efficiency (FPUTE), fertiliser P use efficiency (FPUE) were calculated. Phosphorus application slightly increased PUPE but decreased PUTE and PUE. Increase in P application increased FPUPE, FPUTE and FPUE. Inoculation increased PUPE, PUE and FPUPE at both locations, but increased PUTE, FPUTE and FPUE at NWFP-AU only. Due to increase in yield and improvement in nutritive quality of the soybean seed and shoot in this experiment, inoculation and P application is necessary for high protein and oil yields from soybean seeds as well as for high forage protein yields from soybean planted for forage.