Stressful Effect of Different Rates of Nitrogen Starter Dose on Nodulation, Growth, Proximate Composition and Yield of Soybean (Glycine Max)

Abstract

Despite the fact that high nitrogen content in the soil can impede
nodule formation in soybean, the need for addition of nitrogen
fertilizer as a starter dose to supplement the actions of N-fixing
bacteria is a necessity because it restores the drained nutrient and
results in high yield. To evaluate the stressful effects of different
rates of N fertilizer starter dose, a pot experiment was conducted
to evaluate the effect of N fertilizer starter dose on nodulation,
growth, proximate composition and yield of soybean. Urea was
applied at the rates 0, 50, 75 and 100 kgN/ha at planting using
side placement method. The experiment was laid out in
Randomized Completely Block Design (RCBD) with three
replications. Growth assessment was through taking data on plant
height, number of branches, number of leaves and internode
length. Also, data on nodulation, yield and yield attributes were
taken. Proximate compositions (crude protein, crude fat, crude
fiber and ash content) were also determined. It was found that 100
kgN/ha of N-fertilizer improved the total nodulation by 33.95%
compared with the control. The yield was greatest with
application of 100 kgN/ha compared with other application rates
because there was 20% yield increase compared with the control.
For the proximate composition, crude protein content was 7%
above the control with application of 50 kgN/ha. Furthermore,
crude fat content was 37% better than the control with the
application of 100 kgN/ha. It was concluded that for profitable
soybean production in the study area, the use N fertilizer like urea
at 50 kgN/ha as a starter dose is recommended because of its
cheapness and high yield that resulted from its application to the
crop. Finally, nitrogen starter dose up to 100kgN/ha did not
constitute stress to production of soybean variety under test.