Effects of Foliar Fertilizer Application during the Seed filling period on Soyabean (Glycine Max (L) Merr.) Grain Yield and Seed Quality

Abstract

One major factor that prevents widespread adoption of soyabean (Glycine Max (L) Merr.) has been attributed to low yields. A research study focusing on the development of technologies to increase soyabean productivity and improve seed quality through use of foliar fertilizer during the reproductive stages was conducted at Thornpark Farm (UZ Farm) during the 2006/2007 cropping season. The response of soyabean variety Solitaire to OmniBoost and Folifert Molibor was evaluated. The effect of OmniBoost and Folifert Molibor on Solitaire seed quality was determined through foliar and grain nutrient analysis. Compound D (7% N: 14% P2O: 7% K2O) was used as a basal fertilizer. Foliar fertilizer was applied at three different growth stages during the pod-filling stage, that is, during the 7th, 8th and 9th week after crop emergency. Different applications rates were evaluated as follows; rate I was the control (no foliar fertilizer applied), rate 2 (0.5kg OmniBoost + 0.5L Folifert Molibor, rate 3 (1kg OmniBoost + 1L Folifert Molibor, rate 4 (1.5kg OmniBoost + 1.5L Folifert Molibor), rate 5 (2kg OmniBoost + 2 kg Folifert Molibor) and rate 6 (2.5 kg OmniBoost + 2.5L Folifert Molibor), There was the standard rate recommended by the fertilizer manufacturers (2kg OmniBoost + 2L Folifert Molibor) which was applied at 4 weeks after crop emergency. The experimental design was a 3 x 6 incomplete factorial arranged in an Randomised Complete Block Design (RCBD) with three replications. There was a significant difference (P<0.05) in grain yield and yield components, such as the weight of 1000 seeds and the number of branches per plant. The control, where no foliar fertilizer was applied, was significantly lower than the other treatments. There was also a significant difference (P<0.05) in phosphorus (P) and molybdenum (Mo) content in the grain. The content of P and Mo increased with increase in the rate of foliar fertilizer applied. However, there were no significant differences in the other yield components, which are the number of pods, seeds and barren pods per plant. There was no significant effect of application time, interaction of rate and time on the foliar and grain nutrients (N, P, K, Mg, Ca, Mn, Zn, Fe, Cu). Evaluation of effect of these fertilizers on net income showed that it was only profitable to apply 0.5kg OmniBoost + 0.5L Folifert Molibor. The comparison of how well the crop used supplied nutrients under the respective treatments (Nutrient Use Efficiency) was done using the Agronomic Efficiency (AE) and the Partial Factor Productivity (PFP). Fertilizer use efficiency of N, P, Mg, Mo, B was calculated and it was observed that Agronomic Efficiency and Partial Factor Productivity (PFP) decreased with increase in the rate of foliar fertilizer applied. Germination tests were carried out to determine the viability of the seeds. There was no definite trend, which was established, but some significant differences were observed amongst the treatments. The control was significantly lower than all the other treatments and rate 3 where 1kg OmniBoost + 1L Folifert Molibor was applied during the 9th week after crop emergency was significantly higher than all the other treatments. The other treatments were comparable. It can be concluded that foliar fertilizer application during the pod-filling stage can result in yield increases and grain phosphorus and molybdenum content. It was recommended that farmers use foliar fertilizer at rate 1 (0.5kg 0mniBoost + 0.5L Folifert Molibor) because it was found to be cost effective and farmers would realize less costs.