Resumen

DE OLIVEIRA FERREIRA, Ademir et al. Mudança no conteúdo de carbono en calcio em latossolo melhorado por gesso e calcário no Rio Grande Do Sul. Cienc. suelo [online]. 2013, vol.31, n.1, pp.1-13. ISSN 1850-2067.

The objective of this experiment was to study the effects of different rates of single or combined lime and gypsum soilapplications on the changes in soil carbon (C) and calcium (Ca) and on maize yields under no-tillage in Rio Grande do Sul (RS). maizeTwo experiments were carried out in the main grain production area of Rio Grande do Sul (RS) under a Typic Hapludox. The experimental design in both areas was a randomized block design with three replications. The first experiment evaluated combinations of lime + gypsum at rates of 0.0 + 0.0; 2.6 + 2.0 and 5.0 + 2.0 Mg ha^-1, respectively. The second experiment consisted of seven rates of gypsum ranging from 0 to 6.5 Mg ha^-1.The gypsum and lime materials had 205 and 300 g kg^-1 of Ca, respectively. The soil C was sampled at depths: 0-0.05; 0.05-0.10; 0.10-0.15; 0.15-0.25; 0.25-0.40 and 0.40-0.60 m 6 months after amendment application. The results were submitted to analysis of variance (ANOVA) using the SISVAR 5.0 software and treatment means were compared by the Tukey test (p<0.05). The regression analyses were performed using JMP IN version 7.0.1. In most depths, broadcast gypsum and lime under no-till increased soil Ca content. Soil Ca content showed a linear relationship with soil C under gypsum+lime (p<0.0001) and gypsum applications (p<0.0001). The Ca saturation in the CEC pH 7,0 also showed a relationship with soil C under gypsum+lime (p<0.0001) and gypsum applications (p<0.0001). The treatment with 5.0 + 2.0 Mg ha^-1 gypsum + lime showed increases in soil C up to the 0.40 m-depth compared to the check plot. The highest increase in soil C was observed when Ca saturation in the CEC pH 7.0 was 56.1 and 64.3% for Exp 1 and 2, respectively. In experiment 1, the productivity of maize was 8.6 and 9.9% higher in treatments 2.6 + 2.0 and 2.0 + 5.0 Mg ha^-1 gypsum + lime compared to the control, respectively. In experiment 2, the application of 2.0, 3.0 and 5.0 Mg ha^-1 gypsum reached maize yield increments of 437, 599 and 670 kg ha^-1 , respectively, compared to the control. The increase in maize grain yield was significantly related to soil chemical properties (saturation of calcium in CTCpH7,0 and aluminum saturation).

Palabras clave : Maize; Organic matter; Subtropical soils.

        · resumen en Portugués     · texto en Portugués     · Portugués ( pdf )