EFFECT OF PHOSPHORUS AND POTASSIUM FERTILIZATION LEVEL ON THE GROWTH AND YIELD OF SOYBEAN

Abstract

A field experiment was conducted at the Sher-e-Bangla Agricultural University farm, Dhaka, Bangladesh from December 2013 to April 2014 to evaluate the effect of phosphorus (viz., 0, 100, 175 and 250 kg TSP ha-1) and potassium (i.e., 0, 60, 120 and 180 kg MoP ha-1) fertilization rate and their combination on the growth and yield of soybean. Individual application of different levels of phosphorus and potassium fertilization showed significant effect on growth, yield and yield attributes studied. Leaf area index, numbers of nodule plant-1, numbers of filled pod plant-1, numbers of seed pod-1, 1000-seed weight, seed yield, biological yield and harvest index increased significantly up to 175 kg TSP ha-1 among phosphorus fertilization. The highest (3.01 t ha-1) seed yield was found from 175 kg TSP ha-1 application while the lowest (2.06 t ha-1) from 0 kg TSP ha-1 treatment. On the other hand, plant height, numbers of branch plant-1, leaf area index, numbers of nodule plant-1, fresh weight, dry weight, numbers of filled pod plant-1, length of pod, numbers of seed pod-1, 1000-seed weight, seed yield, stover yield and biological yield enhanced significantly up to 120 kg MoP ha-1 among potassium fertilization. The highest (3.16 t ha-1) seed yield was found from 120 kg MoP ha-1 application while the lowest (2.11 t ha-1) from 0 kg MoP ha-1 treatment. The combined application of phosphorus @ 175 kg TSP ha-1 and potassium @ 120 kg MoP ha-1 gave rise to the highest fresh weight (210.2 g), numbers of filled pod plant-1 (63.00), length of pod (3.16 cm), numbers of seed pod-1 (3.11), and in turn produced highest (3.67 t ha-1) seed yield. Thus, the combined application of 175 kg TSP ha-1 and 120 kg MoP ha-1 may be considered to be optimum for getting higher yield of soybean.