SHORT-TERM EFFECT OF COVER CROPS ON AGGREGATE STABILITY ASSESSED BY TWO TECHNIQUES

Resumen

Aggregate stability (AS) is a property closely linked to soil fluid movement. AS can be determined by different methods and can be improved using cover crops (CC), but the short-term effect of this practice has been little studied. The aim of this study was to evaluate the soil surface aggregate stability of an Argiudoll under no tillage in the Pampas, during the first year after different CC incorporation. AS was determined by using two laboratory techniques: Le Bissonnais and De Leenheer & De Boodt methods, after incorporating different CC (oat, vetch, wheat, oat + vetch) at two different times: after the CC was chemically dried and after the subsequent corn crop harvest. A treatment without CC was also evaluated (fallow between summer crops) as a control. The presence of CC roots improved AS significantly compared to the control, while differences among the various CC were also observed. The presence of corn roots and the residual effect of the decomposition of CC stubble left on the ground also had a positive effect on AS. The various pre-treatments applied by the Le Bissonnais method gave different results: fast wetting of aggregates showed significant differences on AS between the different CC used, whereas slow wetting and mechanical rupture were more effective than fast wetting showing AS differences over time. The results of the De Leenheer & De Boodt method were more erratic and less consistent than those obtained by the Le Bissonnais method.