Mobilidade de K de fertilizante organomineral e mineral em solos de textura contrastante

Abstract

Potassium (K) is the largest macronutrient in plants, but the soil has high mobility, which is especially related to soil texture, cation exchange capacity and element concentration in the soil solution. The element present in the soil solution moves vertically in the profile, being carried by the drainage water and being facial leached to surface layers. Thus, the objective of this work was to evaluate the potassium mobility from organomineral and mineral sources in a dystrophic Red Latosol (LVd) and a typical Ortic Quartzarenic Latosol (RQo) by leaching columns. The experiment was carried out under controlled conditions at the Institute of Agricultural Sciences at the Federal University of Uberlândia, Uberlândia, MG. The experiment was conducted from January to June 2018 in a controlled environment at the Soil Analysis Laboratory - LABAS at the Federal University of Uberlândia - UFU. The experiment was carried out with 30 cm columns and soil samples from 0 to 5, 5 to 10, 10 to 20 and 20 to 30 cm depths. The experimental design was completely randomized with three treatments and five replications for both soils, totaling 30 experimental units. The treatments consisted of three sources (organomineral, mineral and control), and two soil types (Dystrophic Red Latosol and typical Ortic Quartzarenic Neossol). The fertilizers were applied superficially in the established doses. The amount of distilled water in each container varied according to the type of soil, based on the pore volume of each one. For the sandy soil 490 ml was applied and for the clay soil 535 ml the water was placed at intervals one day and the leachate taken the next day after water application, totaling ten percolations in each column in this study. In each application, the volume of percolated solution was determined as well as the amounts of K contained in that solution. After dismantling the soil columns, the exchangeable K contents at different depths were determined. Fertilizer sources had different behavior, regardless of the soil used. The soil type factor has a great influence because it affects the ability to retain and make nutrients available. Sandy soils have a higher K leaching power than clay soils. Organomineral fertilizer had a slower release when compared to mineral fertilizer.