Abstract
Soil liming is a common practice in agriculture. It aims to reduce soil acidity and to supply calcium and magnesium. Lime, however, is not easily soluble in the soil, and its reaction products are often concentrated in the application zone, which is mainly the topsoil layer. In order to increase the concentration of nutrients in deeper layers, agricultural gypsum—a byproduct of phosphoric acid production process, rich in calcium and sulfur—is used. In this context, the objective of this study was to evaluate the chemical attributes of the oxysoil and the corn´s yield to the application of gypsum associated with potassium (K) rates. The study was developed in Uberaba city, Minas Gerais state, Brazil. The factorial scheme was used 5x5, with five rates of K (0, 100, 180, 240, 360 kg ha-1 K2O) and five gypsum rates (0, 500, 1000, 2000, 4000 kg ha-1) in a randomized complete block design with four replications. The soil chemical attributes were evaluated at 0.0-0.20 m and 0.20-0.40 m depth and the biometric and productive attributes of corn. The application of gypsum resulted in the increase of calcium (Ca) and sulfur (S) contents in all depths; reduced the levels of pH, manganese, potential acidity (H + Al) in the 0.0-0.20 m depth, and increase the levels of base of saturation and sum of bases on the 0.20-0.40 m depth. Corn yield and biometric attributes no were influenced by the factors evaluated.
Highlights
In the last decades, the application of industrial waste in agriculture had been characterized as a viable alternative for the nutrient supply of plants and the correction of soil acidity wich minimizing the environmental impacts generated by industrial activities
Chemical attributes In the depth 0.0-0.20 m there were significant interactions between gypsum and potassium doses for the variables K content and Mg/K ratio
In the 0.20-0.40 m depth (Table 2), the application of gypsum and potassium didn’t influence pH (CaCl2 mol L-1) values, corroborating with the results reported by Foloni et al (2008), Rocha et al (2008) and Rampim et al (2011)
Summary
The application of industrial waste in agriculture had been characterized as a viable alternative for the nutrient supply of plants and the correction of soil acidity wich minimizing the environmental impacts generated by industrial activities. The potential acidity characterized by the presence of hydrogen and aluminum ions in the soil solution is a limiting factor in agricultural productivity, because it reduces the availability of nutrients to the plants, causing a reduction of the root system, less absorption of water and nutrients reducing production. The application of gypsum to the soil causes the formation of ionic pairs between SO42- and some cations, which (K+, Ca2+, Mg2+) to depths in the soil. It due to high solubility, it does not change the electric charges of the soil and increase the sulfate anion (SO42-) concentration in the soil solution (ERNANI; RIBEIRO; BAYER, 2001). Induce deficiency of these nutrients, especially in soils with low retention capacity of cations and organic matter
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