Abstract:
An experiment was conducted at the Instructional Farm attached to the College of Horticulture, Vellanikkara during July to October 1978, to study the effect of phosphorus nutrition, liming and rhizobial inoculation on soybean (Glycine max (L.) Merril).
The investigation was taken up with the objective of arriving at the phosphorus requirement of the crop, assessing the response to liming and evaluating the effect of rhizobial inoculation. The trial was also aimed at studying the possible interaction effects between these factors.
The experiment was laid out as a factorial in randomized block design with 16 treatments and 3 replications.
The study revealed that applied phosphorus did not significantly affect any of the growth characters consistently. Grain yield and yield attributes were also unaffected but stover yield increased with higher doses of applied phosphorus.
In general, nitrogen, phosphorus and calcium contents in plant components were unaffected by levels of phosphorus, liming and rhizobial inoculation. Uptake of these nutrients also remained almost unchanged. At harvest, nitrogen uptake by seeds constituted 44 per cent of the total, remaining being accumulated in stem + petiole and shell. In the case of phosphorus, 86.9 per cent of the total accumulation was in seeds, 6.0 percent and 7.1 per cent being in stem + petiole and shell respectively. Calcium being an immobile nutrient and an element not translocated within the plant, proportion of uptake of calcium in various components of the plant was different from that of nitrogen and phosphorus. In contrast to nitrogen and phosphorus, only 24.9 per cent of the total was found in seeds whereas 36.3 per cent and 38.8 per cent of it were concentrated in stem + petiole and shell respectively.
Levels of phosphorus, had no effect on total nitrogen and available potassium contents of soil after harvest of the crop but there was a notable increase in available phosphorus and decrease in exchangeable calcium. Liming and rhizobial inoculation did not have any conspicuous effect on the content of nutrients in soil.
