and P (Rhoton, 2000) accumulate in the upper few centimeters under NT compared with CT soil, which may Tillage system affects many soil parameters that may influence reduce Al toxicity. Other nutrients also accumulate near plant growth. This study evaluated the effect of liming on corn (Zea mays L.) yield and chemical characteristics of a Humic Hapludox the surface in NT soils (Rhoton, 2000), causing increases (clayey, kaolinitic, goethitic, termic) under both conventional tillage in the concentration of electrolytes, reductions of soil (CT) and no-tillage (NT) systems. Rates of dolomitic lime, from 0 to pH, and increases in both Al activity (Ernani and Bar-18 t ha Ϫ1 , were plowed into the soil in 1992 in southern Brazil; our ber, 1991) and P sorption. These effects may offset the study was conducted from 1996 through 1999. Lime rate was allocated benefits of soil organic matter (SOM) and P accumulato subplots, and tillage systems to main plots, in a split-plot design.tion on Al toxicity in NT soils. Corn yield increased with liming in all years and was higher with CTVariations in soil pH also affect availability of most than with NT in 2 of 3 yr. Averaged across years and systems, liming soil nutrients (Helyar and Anderson, 1974, Ernani et increased yield by 66%, which ranged from 4.4 to 7.8 t ha Ϫ1 . The al., 1998), organic matter decay (Azevedo et al., 1996), highest average yield (7.8 t ha Ϫ1 ) was obtained at pH 6.5; yields at N mineralization, and some physical and chemical prop-pH 6.0 or 5.5 were 97 and 89% of the maximum, respectively. Liming reduced soil organic matter (SOM) in both systems, but nutrients (P, erties (Albuquerque et al., 2000), especially on highly K, Ca, Mg, Fe, Cu, Zn, and Mn) remained above sufficiency on all weathered soils. The magnitude of these changes varies treatments. Aluminum, pH, SOM, and other nutritional parameterswith soil, soil pH range, organic matter content, and did not differ between tillage systems, partly because limestone was tillage system (Torbert et al., 1998). Thus, liming has initially incorporated in all plots and partly due to dilution effects in direct and indirect effects on nutrient availability and the plow layer because sampling was not stratified in small depths.

Tillage system affects many soil parameters that may influence plant growth. This study evaluated the effect of liming on corn (Zea mays L.) yield and chemical characteristics of a Humic Hapludox (clayey, kaolinitic, goethitic, termic) under both conventional tillage (CT) and no‐tillage (NT) systems. Rates of dolomitic lime, from 0 to 18 t ha−1, were plowed into the soil in 1992 in southern Brazil; our study was conducted from 1996 through 1999. Lime rate was allocated to subplots, and tillage systems to main plots, in a split‐plot design. Corn yield increased with liming in all years and was higher with CT than with NT in 2 of 3 yr. Averaged across years and systems, liming increased yield by 66%, which ranged from 4.4 to 7.8 t ha−1. The highest average yield (7.8 t ha−1) was obtained at pH 6.5; yields at pH 6.0 or 5.5 were 97 and 89% of the maximum, respectively. Liming reduced soil organic matter (SOM) in both systems, but nutrients (P, K, Ca, Mg, Fe, Cu, Zn, and Mn) remained above sufficiency on all treatments. Aluminum, pH, SOM, and other nutritional parameters did not differ between tillage systems, partly because limestone was initially incorporated in all plots and partly due to dilution effects in the plow layer because sampling was not stratified in small depths. Some soil restriction impaired by absence of plowing, probably increases in bulk density, offset the benefits of NT on plant growth and was responsible for the smaller yield in this tillage system compared with CT.