Ciencia del Suelo (Jul 2011)
Cultivos de cobertura: efectos sobre la macroporosidad y la estabilidad estructural de un suelo franco-limoso Cover crops: effects on soil macroporosity and soil structural stability in a silt loam soil
Abstract
Los suelos franco-limosos manejados con siembra directa a menudo poseen porosidad estructural baja e inestable. Con el objetivo de determinar la capacidad de los cultivos de cobertura (CC) de mejorar la porosidad y estabilidad estructural de estos suelos se llevaron a cabo experimentos de campo y de invernáculo. Ambos tuvieron tratamientos con y sin CC (avena, Avena sativa L.), en rotación con soja (Glicine max L. Merr.). Luego de los CC se midieron densidad aparente (DA), el índice de inestabilidad estructural (IE) y en el ensayo de invernáculo además, se midió la evolución de la distribución de tamaño de poros (DTP). En ambos ensayos la introducción de CC no disminuyó la DA, aunque incrementó la estabilidad del suelo (PNo- till (NT) silt loam topsoils have often a low and unstable structural porosity. The objective of this study was to determine the capability of cover crops (CC) of improving the structural porosity and stability of silt loam soils under NT. Greenhouse and field experiments were carried out on a silt loam soil (Typic Argiudoll) with and without CC (oat, Avena sativa L.) in crop sequences with soybean (Glicine max L. Merr.). Soil bulk density (DA) and aggregate instability index (IE) were measured after the CC in both experiments. In the greenhouse experiment, soil pore size distribution (DTP) was measured. The use of CC did not change DA, but soil IE was significantly lower in crop sequences with CC (P < 0.05) both under field and greenhouse conditions. Stability increases were likely due to the effect of CC residues and root mass. No differences in DTP were found between treatments, although a significant effect of sampling date was observed (P<0.05). Changes in DTP were due to significant increases in mesopore (517.5%) and macropore (52.7%) volumes. Such changes occurred in all the treatments, probably due to the soil wetting-drying cycles. The results found in this study agree with other studies carried out on silt loams in the same region, which also found a lack of effect of tillage practices on soil porosity.. A low soil structural resilience of silt loam soils in the short-term is corroborated.
