Soybean Yield in Response to Foliar Application of Magnesium and Potassium in a Cerrado Environment
摘要
The practice of foliar fertilization is intended not only to reduce problems caused by macro and micronutrient deficiencies, but also to provide specific nutrients at strategic moments of crop development. The objective of this study was to evaluate the influence of foliar fertilization with magnesium (Mg) and potassium (K) on the yield components and leaf macronutrient contents of soybean crop. Two experiments were carried out with soybean (Brasmax Foco IPRO) in the 2019/2020 season. The first experiment was carried out using Mg sources (MgSO4, MgO and MgCl2) alone at dose of 0.54 kg ha− 1 and associated with K2O sulfate (1 kg ha− 1). The second experiment was carried out with foliar application of 5 doses of Mg in the form of Mg sulfate (0, 3, 6, 9 and 12 kg ha− 1). At the R1 phenological stage of the soybean crop, the SPAD index was evaluated and leaves were collected to determine leaf contents. At the end of the crop cycle, number of pods, thousand-grain weight, number of grains and number of grains per pod were determined. Yield was also determined for each treatment. There was no significant difference between the sources of Mg, associated or not with K sulfate. Application of increasing doses of MgSO4 increased the yield of the soybean crop. MgSO4 dose of 4.2 kg ha− 1 promoted the highest yield, equivalent to 4,555 kg ha− 1. Leaf Ca and Mg contents were maximized when the MgSO4 doses of 9.2 and 6.0 kg ha− 1 were applied, respectively. MgSO4 dose of approximately 9 kg ha− 1 ensured the highest leaf contents for these nutrients. Application of MgSO4 at dose of 4.2 kg ha− 1 was efficient in increasing soybean yield and maintaining its adequate nutritional status.