Influence of sulphur and zinc levels and zinc solubilizer on productivity, economics and nutrient uptake in groundnut (Arachis hypogaea)

The field experiments were conducted over 2 consecutive rainy (kharif) (July to November) seasons of 2013 and 2014 at New Delhi, to evaluate the effect of 3 sulphur (S) levels (0, 20 and 40 kg S/ha), 4 zinc (Zn) levels (0, 2.5, 5.0 and 7.5 kg Zn/ha) and 2 zinc bio-fertilizer (Native zinc solubilizer) levels (Control and seed treatment with zinc bio-fertilizer) on the performance of groundnut (Arachis hypogaea L.). Sandy loam soil of the experimental field was low in available S and DTPA-extractable Zn. Application of S caused marked improvement in plant height, branches/plant, leaf area index (LAI), pods/plant and pod and haulms yields, net returns, S-content in kernel and S and Zn-uptake up to 40 kg S/ha. Based on 2 years average, application of 20 and 40 kg S/ha resulted in 23.4 and 31.4% increase in pod yield, 36.3 and 52.7% in haulms yield, 46.3 and 56.7% in net returns, 66.3 and 92.3% in S-uptake in kernel and 25.9 and 35.3% in Zn-uptake/ha in kernel over control, respectively. Application of Zn had significant effect on growth and yield attributes, pod and haulms yields, shelling percentage, net returns and Zn-content and uptake in kernel only up to 5.0 kg Zn/ha. Application of 2.5, 5.0 and 7.5 kg Zn/ha resulted in 17.2, 21.1 and 13.6% increase in pod yield, 36.1, 45.0 and 27.4% in net returns, 17.5, 18.5 and 6.3% in S-uptake and 29.4, 44.9 and 45.5% in Zn-uptake in kernel over control, respectively. Effect of Zn-bio-fertilizer was significant on growth and yield attributes (except kernels/pod), pod and haulms yields, shelling percentage and Zn-content and uptake. Due to application of Zn bio-fertilizer 4.7, 6.2, 9.2, 5.2 and 7.9% increase in pod yield, haulms yield, net returns, S-uptake in kernel and Zn-uptake in kernel was recorded over control. Based on two years average, response to S and Zn application was quadratic and economic optimum dose was worked out to be 39.0 and 4.5kg/ha, respectively. Hence application of 39kg S and 4.5 kg Zn/ha with Zn-solubilizer is recommended for improving the productivity and profitability of groundnut in sandy loam soils low in S and Zn.