Foliar Application of Macro- and Micronutrients Improves the Productivity, Economic Returns, and Resource-Use Efficiency of Soybean in a Semiarid Climate

Inadequate nutrient management is one of the major challenges for sustainable soybean production in semi-arid climatic conditions. Hence, a 3-year (2015-2017) field experiment was conducted to assess the effect of foliar application of macro- and micronutrients on the growth, productivity, and profitability of soybean. Eight foliar nutrient sprays at the pod initiation stage-water spray (WS), 2% urea solution, 2% di-ammonium phosphate solution (DAP(2%)), 0.5% muriate of potash solution (MOP0.5%), 2% solution of 19:19:19 nitrogen phosphorus and potassium (NPK2%), and a 0.5% solution each of molybdenum (Mo-0.5%), boron (B-0.5%), chelated-zinc (Zn (0.5%)) and no-foliar nutrition (NFN)-were compared with a basal-applied recommended dose of fertilizers (RDF: 30 kg N, 75 kg P, and 40 kg K ha(-)(1)) in a randomized block design (RBD), replicated three times. Foliar-applied chelated Zn@0.5% (Zn-0.5%) at the pod initiation stage resulted in more pods per plants. In addition to Zn-0.5%, urea(2%), NPK2%, and B-0.5% significantly improved the pods per plant over treatment by no-foliar nutrition (NFN). The RDF-supplied soybean subsequently sprayed with Zn-0.5% produced the highest seed yield, which was 18.5-37.8% higher than that of NFN treatment Yield improvement due to the application of B-0.5%,B- DAP(2%), and urea(2%) varied between 19.2-23.7, 16.6-20.4 and 18.6-20%, respectively. Foliar nutrition showed the largest net returns from Zn-0.5%. The water-use efficiency (WUE) and production efficiency increased by 18.4-37.6 and 34.9-37.5%, respectively, due to Zn-0.5% over the efficiencies from NFN treatment. Monetary efficiency (ME) gains due to Zn-0.5% were 24% higher, while ME efficiency gains due to urea(2%), NPK2%, and B-0.5% varied between 15-16%. Thus, this study suggested that the foliar application of 0.5% Zn and B, urea, NPK fertilizer, and DAP at 2%, along with RDF. is a profitable nutrient management option for quality soybean production in a semiarid region. However, nutrient partitioning, changes in soil chemical and biological indicators, and environmental aspects need critical examination in future studies.