The objective of this study was to evaluate the long-term effects of soil tillage systems and methods of lime application on biological, physical and chemical attributes of a clayey aluminic Oxisol, and on soybean yield components. The experiment with tillage systems was installed in 1978 in Guarapuava, PR, southern Brazil, and liming methods began to be tested in 1987. The treatments were: conventional tillage (CT) without liming; CT with liming; no-tillage (NT) without liming; NT with surface liming and NT with incorporated lime. Soil and plant analyses were performed during the 2002-2003 soybean growing season. No soil physical-structural restrictions were observed under CT and NT. In the surface soil layer NT with and without surface liming showed higher aggregate stability than CT. Aggregate stability was lower in NT with incorporated liming than in NT without soil mobilization. The aggregate stability was positively related to mycorrhiza mycelial length and organic carbon contents. The volumetric soil moisture and available water were higher in the surface layer in NT without and NT with surface liming. In the 0.20 to 0.30 m layer, NT without liming stored more water than CT. NT presented higher soil organic carbon and P contents than CT. The higher P content in the soil favours plant uptake and P accumulation in soybean leaf tissue. Liming reduced soil Al levels and increased soil pH and Ca and Mg contents. Liming under CT increased Mg, P and N contents in plant tissues, plant height and weight of 1,000 grains. Lime incorporation under NT did not affect tissue nutrient concentrations or soybean yield, but increased plant height in relation to NT with surface liming. Therefore, under the studied conditions it is not necessary to incorporate limestone under NT system. Soybean yield was not affected by liming, but it was 16% higher under NT than in CT.
no-tillage; conventional tillage; soil aggregation; available water; Glycine max; nutrients
