Resumo

GONZALEZ, Hugo Martín; RESTOVICH, Silvina Beatriz  e  PORTELA, Silvina Isabel. Utilización de cultivos de cobertura invernales como alternativa para mejorar la estabilidad estructural del suelo. Cienc. suelo [online]. 2017, vol.35, n.1, pp.1-10. ISSN 1850-2067.

Cover crops (CC) are sown between two harvest crops and could mitigate soil physical degradation in simplified cropping systems. In this study we evaluated the effect of different CC on aggregate stability and other variables that affect soil aggregation after six years of soybean-maize rotation under no tillage. We evaluated soil samples from a long-term experiment with different species used as CC and measured soil organic carbon, glomalina and aggregate stability using the Le Bissonnais method. Aggregate stability was 20-25% higher in rotations with CC than in the control without CC. The use of rescue grass, oats, vetch and oats+vetch as CC produced more stable aggregates than ryegrass, barley and the control after fast wetting pre-treatment. Grasses, except rescue grass, produced more stable aggregates than the control after mechanical breakdown pre-treatment and there were no differences in aggregate stability after the slow wetting pre-treatment. Soil organic carbon explained 49% of the variation of aggregate stability after the fast wetting pre-treatment. Soil total glomalin content explained 60 and 70% of the variation of aggregate stability after the slow and fast wetting pre-treatments, respectively, and the cover crop C/N ratio explained the variation of aggregate stability after the mechanical breakdown pre-treatment (R²=0,70). Cover crops improved soil structural stability in the mid-term by reducing aggregate slaking after fast wetting (rescue grass, oats, vetch and the oats+vetch mixture), or through aggregate protection against rain drop impact achieved by durable stubble (ryegrass, barley and oats).

Palavras-chave : Le Bissonnais method; Soil organic carbon; Glomalin; Aboveground biomass C/N ratio.

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