Granulometria e doses de calcário em diferentes sistemas de manejo

Granulometric fractions and lime rates in conventional and no-tillage system. The use of limestone in no-tillage system usually causes great problems in soil management. The objective of this work was to evaluate the changes in the chemical properties of the soil under no-tillage (NTS) and conventional tillage system (CTS) due to granulometric fraction [Effective Calcium Carbonate (ECC) = 95% and 56%] and three rates (95% ECC = 1.2, 2.4 and 3.6 t [ha.sup.-1] and 56% ECC = 2, 4 and 6 t ha-1) of dolomite lime applied in surface two months prior to system implantation. The experiment was carried out in a split-plot design with four replications in a dystrophic Red Latosol (Oxisol) during three years, in area of pasture of Urochloa decumbens using a succession of corn and black oat. The soil chemical characteristics (pH, Ca, Mg, H+Al and base saturation) were analyzed in 12, 24 and 36 months before each sowing in the depths 0-5 cm, 5-10 cm, 10-20 cm and 20-40 cm. The results evidenced alterations in soil chemical properties with pH increase, exchangeable calcium and magnesium, base saturation, and reduction of potential acidity up to 10 cm of depth in NTS, with significant differences in relation to CTS. In the depths of 10-20 cm and 20-40 cm, there was an inversion, and the effects in the neutralization of soil acidity were more pronounced in the CTS than the NTS. The application of lime with 95% ECC showed better neutralization of soil acidity up to 10 cm of depth. The use of lime with 95% ECC provided better neutralization of the acidity of the soil up to 10 cm of depth. The corrective application in surface before the implantation of SPD was enough to elevate the base saturation for levels adapted for the corn yield. Keywords: soil acidity, pH, liming, base saturation, soil management. A utilizacao de calcario em plantio direto e um dos problemas na adocao desse metodo de manejo do solo. O trabalho teve por objetivo avaliar as alteracoes nas propriedades quimicas do solo cultivado nos sistemas de plantio convencional (SCC) e plantio direto (SPD), em funcao da granulometria e de doses de calcario dolomitico aplicado em superficie. Os experimentos foram realizados por tres anos agricolas em Latossolo Vermelho distrofico, em area de pastagem de Urochloa decumbens, com cultivo de milho em sucessao com aveia preta e triticale. O delineamento experimental utilizado foi os blocos casualizados em parcelas sub-subdivididas, com quatro repeticoes. Foram realizadas a