Foliar application of micronutrients and potassium in soybean crop

Foliar fertilization can improve plant nutrition and yield of soybean crops, especially in low-fertility sandy soils. This study investigated the agronomic efficiency of using micronutrient-based foliar fertilizers during the vegetative stage combined with potassium foliar fertilization during the reproductive stage on production components and grain yield of soybean crops in sandy soils of the Cerrado. The treatments consisted of the application of five micronutrient-based foliar fertilizers during the V4 vegetative stage [Big Red® (Cu), Maxi Zinc® (Zn), Supa Moly® (Mo), Boster® (Zn, Mo) and CMZ Infinity® (Cu, Mo, Zn)] in association or not with the application of the K-based foliar fertilizer Yantra® during the R3 reproductive stage. An additional treatment without foliar fertilizer application was used as a control. The treatments were arranged in a randomized block design in a 5 × 2 + 1 factorial scheme with four replications. The results showed that the application of foliar fertilizers containing Zn and Mo (Boster®) and Cu, Zn and Mo (CMZ Infinity®) are the best alternatives for use in soybean crops, as they result in greater plant height, height of first pod insertion, number of pods, total pod weight and higher grain yield, regardless of the association with K-based foliar fertilizer in the reproductive stage. The application of foliar fertilizers based on micronutrients and K had no impact on the thousand-grain mass of the soybean crop. The foliar application of K at the reproductive stage resulted in higher soybean grain yield when associated with the application of Zn (Maxi Zinc®) and Mo (Supa Moly®) at the vegetative stage.