Response of corn to potassic organomineral fertilizer in an Oxisol

Purpose: Corn (Zea mays L.) requires an adequate supply of potassium (K) to achieve high productivity. Potassium chloride (KCl) is the main fertilizer source used, but its excessive application can increase soil salinity and production costs. Organomineral fertilizers (OMF) have emerged as an alternative, as they improve soil attributes and supply nutrients. In this study, the effects of an OMF fertilizer were compared with KCl, based on the external critical level (CL) of K for corn in a sandy loam Typic Hapludox. Method: The experiment was conducted in a greenhouse using a randomized complete block design with five treatments and four replications. The applied K rates ranged from 40% below to 20% above the CL. Biometric and plant tissue data were evaluated. Results: OMF showed equivalent or superior efficacy compared to KCl, especially at rates suitable for the crop. The use of OMF enhanced calcium and magnesium uptake and exhibited the highest agronomic efficiency of K use across all evaluated rates, with an average value 24% higher than that of KCl. Both fertilizers had similar K uptake efficiency, while apparent recovery efficiency ranged from 55 to 70% for OMF and 77 to 94% for KCl. Conclusion: Both fertilizers exhibited similar efficacy, and the choice should consider availability and cost. In addition to being a viable alternative, OMF offers environmental benefits and contributes to organic waste management, promoting more sustainable agricultural practices and aligning with the United Nations Sustainable Development Objectives. Highlights · Organomineral fertilizer (OMF) increased potassium agronomic efficiency. · OMF improved calcium and magnesium uptake in corn plants. · OMF showed equal or superior performance to KCl in corn growth. · Potassium rates above the critical level did not improve plant productivity. · OMF promotes sustainable waste management and reduces KCl dependence.