COMBINAÇÃO DA GESSAGEM E DA CALAGEM EM ATRIBUTOS QUÍMICOS DO SOLO E NA PRODUÇÃO DE GRÃOS E FORRAGEM EM SISTEMA PLANTIO DIRETO

Abstract

After long periods of continuous no-till (NT) management, a vertical gradient in soil chemical attributes is formed, and soil acidity combined to low levels of nutrients in subsurface layers may limit crop yield. The surface application of the adequate lime and gypsum rates can correct such problems over time, improve the continuous NT results, and eliminate soil tillage requirements. In this study, the residual effects of gypsum rates (0, 3, 6, 9, and 12 Mg ha-1) split applied in 2009-2010, and dolomitic lime rates (0, 5.67 and 10.21 Mg ha-1) applied in 2014, were evaluated for chemical attributes of a Typic Hapludox, nutritional aspects and yield of annual crops. In the crop season of 2017/2018, corn (dual-purpose) was sowed, followed by forage oat (2018), common bean (2018/2019), fall cover oat (2019) and barley (2019). Nutrition and grain yield were evaluated for corn, common bean and barley. Forage dry matter yield (DMY) and nutrient extraction were evaluated for corn and oat. After corn harvest in 2018, the soil was sampled up to 0.8 m for chemical analysis. Without liming, gypsum rates resulted in higher soil reacidification nine years after the application, decreasing soil pH up to 0.10 m and increasing Al3+ up to 0.20 m. Liming increased the soil pH and reduced H+Al and Al3+ up to 0.80 m, but only the rate of 10.21 Mg ha-1 of lime decreased H+Al and Al3+ in 0.20-0.40 m layer and increased the soil pH at 0.60-0.80 m. Gypsum increased Ca2+ levels up to 0.80 m depth, while liming promoted this effect only up to 0.10 m. Gypsum reduced Mg2+ from 0.40 to 0.80 m, and from 0.10 up to 0.60 m this effect only occurred without liming. Lime rates increased Mg2+ in all layers, but below 0.40 m depth this effect occurred only with 10.21 Mg ha-1 of lime. Gypsum and lime applications decreased the K+ levels between 0.10 and 0.40 m. Gypsum increased the concentrations of N, Ca and S in corn leaves, Ca in bean leaves, and Ca and S in barley leaves, and decreased Mg concentrations in corn and barley leaves. Liming increased the leaf concentrations of Mg in these three crops, and those of N in corn leaves, Ca in bean leaves, and P, Ca and Mg in barley leaves. Corn grain yield increased up to the estimated rate of 7.21 Mg ha-1 of gypsum, and also with liming, but without difference between lime rates. The grain yield of bean increased only with the application of 10.21 Mg ha-1 of lime. The yield of barley was strongly affected by frost and hail, but increased with gypsum application up to the estimated rate of 5.46 Mg ha-1 . Liming increased the DMY of corn forage and the accumulation of all nutrients, while gypsum increase the Ca accumulation when combined with lime. In both crops, gypsum increased N accumulation, and in oat forage gypsum increased the Mg accumulation when combined with 10,21 Mg ha-1 of lime, while liming increased the accumulations of K and S, and in the absence of gypsum lime increased Mg accumulation.