Propriedades químicas do solo sob efeito residual da aplicação de gesso agrícola em superfície

Abstract

The use of agricultural gypsum has been increasing due to its ability to reduce toxic aluminum levels, as well as to promote the leaching of calcium, magnesium, and potassium into the subsurface soil layers. This process aims to correct the soil profile, creating a favorable environment for root development, which is essential during periods of water deficit. The present study aims to evaluate the influence of increasing gypsum application rates on the reduction of aluminum ions in the subsurface and the potential leaching effects of potassium and magnesium, which may be enhanced by higher gypsum doses. The evaluation was conducted across soil layers at depths of 0–10, 10–20, 20–30, 30–40, 40–50, and 50–60 cm, three years after gypsum reapplication. The experimental design followed a randomized block layout with five treatments (0, 2, 4, 6, and 8 t ha⁻¹), with gypsum reapplication carried out on the soil surface in June 2021. The assessment involved determining chemical parameters including: pH, exchangeable calcium, magnesium, and aluminum, available phosphorus and potassium, base saturation, and aluminum saturation down to the subsurface layers. Agricultural gypsum did not significantly alter soil pH, exchangeable aluminum, or base saturation. It showed limited influence on magnesium levels, with a noticeable increase only at the 40–50 cm layer. A decrease in surface calcium and base sum was observed, along with changes in phosphorus content in the 0–10 and 10–20 cm layers. Potassium showed a linear decrease down to 30 cm and increased in the deeper layers with the 2 and 4 t ha⁻¹ doses, indicating possible leaching of this element.