Dinâmica do potássio e resposta do milho à fertilização com fonte organomineral em solo franco-arenoso

Abstract

Potassium dynamics and corn response to fertilization with an organomineral source in sandy loam soilBrazil has high external dependence on potassic fertilizers, which leaves the country's agricultural production sensitive to supply and demand shocks for this input. Given this scenario, alternative sources of potassium (K), such as organomineral fertilizers (OMF), have been increasingly used in Brazilian agriculture. However, there are few detailed studies regarding the dynamics of K in the soil and the response of plants to OMFs. The objectives of this study were: (i) to quantify the release of K from a OMF and evaluate its influence on chemical, physical and microbiological attributes of a sandy loam soil, (ii) to evaluate whether the use of OMF influences the communities of soil bacteria and fungi compared to KCl and (iii) compare the effects of rates of a K source OMF based on the critical level (CL) of K for corn (Zea mays) compared to KCl. OMF released K more slowly over time, which can be beneficial to plants as it provides a constant supply of nutrients. K leaching in the OMFfertilized soil was slower in the column experiment than in the KCl-fertilized soil. OMF treatment stimulated greater microbial activity, but reduced the richness and diversity of bacteria and fungi in the soil. For corn plants, the soil fertilized with OMF had equivalent or superior efficacy to KCl, especially in rates suitable for the crop. Furthermore, rates above the CL of K in the soil did not result in yield gains. Therefore, this study highlights the potential of OMF as a viable alternative for Brazilian agriculture, which can contribute to the safety and sustainability of agricultural production.