Kamafugito proveniente da região do Alto Paranaíba - MG como remineralizador de solo

Abstract

In order to evaluate the use of kamafugite as a soil remineralizer, three experiments were carried out: Incubation, leaching and biological tests. All tests were conducted in a greenhouse located in the Uberlândia Federal University, using samples from two types of soil, Dystrophic Red Latosol (LVd) and the typical Ortic Quartzarenic Neossol (RQo) and two kamafugite forms, filler and powder granulometries. In the first experiment, the objective was to evaluate the ability to release potassium, phosphorus, calcium and magnesium from the kamafugite (filler and powder) applied in natura and compare with conventional soluble sources (Triple superphosphate - TSP; potassium chloride - KCl and calcium carbonate - CaCO3). Two kamafugite granulometries (filler and powder) and four doses of the product (1250, 2500, 5000 and 7500 mg dm-3) were used. After 60 days, the nutrient content (P, K, Ca and Mg) in both types of soil was determined, as well as the pH of the soil. The kamafugite proved to be effective in increasing the content of nutrients in the soil, mainly for the highest applied doses, however, still below the effectiveness of the soluble sources; the filler form is more efficient than the powder form, in general. The second experiment aimed to evaluate the losses by leaching of potassium from granulated potassium chloride, kamafugite filler and powder and potassium nitrate powder in samples of LVd and RQo. The treatments were distributed in leaching columns, 20 cm in diameter and 70 cm high. Kamafugite was less prone to leaching losses when compared to potassium chloride and potassium nitrate. In the biological tests, installed in pots, two consecutive cultivations were carried out, the first with rice and the second with brachiaria, and aimed to evaluate the agronomic efficiency (IEA) and residual effect of kamafugite filler and powder at doses of 1667, 3334, 6668 and 13336 mg dm-3 of soil, to supply P, K, Ca and Mg and, compared with treatments with TSP, KCl and the control, without application of P and K. The IEA values of kamafugite were higher in the second crop, showing good residual effect compared to soluble sources. The remineralizer was efficient in increasing the levels of nutrients in the soil and accumulated in the plants, mainly for P. The filler and powder forms showed a similar effect on the release of nutrients for the soil and for the plants. Kamafugite can be considered a potential source for the supply of P, K, Ca and Mg for agriculture, as it is a natural brazilian source.