Soils of the subtropical highlands of Brazil are nutrient-poor and have high lime requirements, which increases costs and can limit the acidity correction. The objective of this study was to assess chemical and physical modifications of an aluminic Humic Cambissol, and the response of wheat crop to the application of alkaline residue from paper and cellulose industry. The treatments consisted of residue rates corresponding to 25, 50 and 100 % (respectively 2,625, 5,250 and 10,500 kg ha-1) of the recommended liming by the SMP method, to increase pH up to 6.0, in comparison with dolomitic limestone at rates of 50 and 100 % SMP (respectively 5,600 and 11,200 kg ha-1), and the control treatment, with no residue and no lime application, in an experimental design of random blocks with four replicates. The lime was surface-applied in 2004, on a grazed native grassland area, without incorporation. Soil samples were collected from the layers 0-5; 5-10 and 10-15 cm for soil chemical and physical analyses. In 2006, the foliar nutrient contents and grain yield of the wheat crop were evaluated. Surface application of alkaline residue improved soil chemical properties, mainly in the surface layer, and increased soil pH, and Ca and Mg contents. However, the Ca:Mg molar ratio and sodium contents increased, without reaching the critical Na saturation in the soil CEC. Surface liming with residue or limestone linearly decreased the degree of clay flocculation in the surface soil layer. Foliar nutrient contents and grain yield were similar in the liming treatments, with positive response to lime rates.
dregs; nutrients; sodium; soil structure
