A field experiment was conducted in the state of Paraná, Brazil, to evaluate the effect of liming on soil acidity, soil nutrient availability and yields of maize and soybeans on a Red Latosol (Oxysol), which had been cultivated for three, six and nine years under no-tillage (NT). Lime was broadcasted to the soil surface in four rates- 0, 33.3, 66.7 and 100% of the amount calculated to increase the soil base saturation (V%) to 70%; an additional treatment consisted of broadcasting the highest rate of lime and mixing it to the 0-20 cm layer of the soil. Calcium, magnesium and V% showed the most uniform distribution in the profile when the soil was cultivated under NT for nine years; in addition, exchangeable Al was low and pH was constant in all the studied soil layers. In the soil cultivated for three years, the highest figures for Ca and Mg in the 0-5 cm layer were observed when lime was broadcasted on soil surface at full rate, while pH and V% did not change with liming. The highest rate of lime mixed in the soil increased pH and Ca content of the 10-20 cm layer, as well as the Mg and V% of both layers of 10-20 and 20-30 cm. This treatment also reduced the Al content of the 20-30 cm layer. In the soil with six-year cultivation period pH, Ca and Mg of the upper layer generally increased with the highest rates of lime broadcasted to the soil surface. When mixed to the soil, lime reduced the exchangeable Al and increased the V% and the content of Ca and Mg of the deepest soil layers. In the soil cultivated for nine years, lime influenced only the surface layer; when applied on the surface, the increase in pH, V%, Ca and Mg by lime was generally higher than when mixed to the soil. Liming did not influence the contents of N, P, K and S in the soybean leaves. Maize and soybean grain yields were not influenced by liming, but the soil with six years of cultivation under NT produced the highest soybean yield.
calcium; magnesium; nitrogen; phosphorus; potassium; sulphur