Calagem em latossolo vermelho-amarelo cultivado com variedades de cana-de-açúcar no Brejo paraibano.

Abstract

Brazil is the world's largest producer of sugarcane, with extensive cultivable areas combined with a favorable climate, the country produced 642.7 million tons of sugarcane in the 2019/2020 harvest, 29.8 million tons of sugar and 1.6 billion liters of ethanol. Sugarcane has a participation equivalent to 38.9% of the agricultural activities of Brejo Paraibano, thus, it is considered the most dominant crop in the micro-region. The practice of liming corresponds to a fundamental management for the improvement of the fertility of tropical soils in which the sugarcane cultivation areas are installed. In this way, the work aimed to evaluate the effects of liming on the chemical attributes of Red-Yellow Dystrophic Oxisol cultivated with sugarcane in the Paraíba swamp and its effect on macronutrient absorption in four sugarcane varieties grown in the Paraíba swamp. The experiment was organized in an experimental design using randomized blocks with 20 treatments organized in a subdivided plot consisting of 10 varieties and 2 conditions of land use (with and without liming), with four replications. The plot consisted of the limestone factor and the subplot constituted by the variety factor. The fertilization as well as the application of the limestone were made based on the soil analysis. The amount of 2.8 t ha-1 of limestone was evenly distributed according to the treatments, with cover fertilization at 90 days after cutting the cane plant, with 280 kg ha-1 of N, 152.83 kg ha 1 P and 133.33 kg ha-1 of K to maintain the cane experiment. The experimental sampling was carried out in the cultivation areas of the varieties: RB93509; RB002754; RB962962; SP79-1011, due to the fact that they have a greater productive contribution to sugarcane. Three points were sampled within each subplot, with the sample points positioned at the ends and in the middle of each subplot. At each sampling point, soil samples were collected at a depth of 0-20 cm, totaling 96 samples. Liming provided an increase in pH (16%) as well as a significant increase in Ca (30%), Mg (18%), in addition to reducing K (19%) and Al (14.7%). However, liming was not significantly expressed on soil CTC. The nutritional concentration of the analyzed genotypes showed significance for the levels of N and K. The liming practice promoted changes in pH and significant increases in nutritional levels for Ca and Mg.