Mechanisms of aggregation in a silty loam under different simulated management regimes

Silty loams of the rolling Pampa of Argentina are affected by different soil degradation levels. It is still poorly understood how soil degradation affects the regeneration of a desirable topsoil structure in pampean silty loams. A greenhouse pot experiment was carried out to evaluate changes in soil aggregation after 4 and 12 months exposure to varying: (i) soil management regimes: pasture, conventional tillage (CT) and eroded conventional tillage (CTer); (ii) water regimes: constant field capacity (FC) and wetting–drying cycles (W/D); and (iii) vegetation: sterilized and ryegrass. After 4 months (October–January), the size of aggregates measured by their mean weight diameter (MWD) after dry sieving, varied from 1.78 to 3.54 mm. This was significantly increased by soil degradation level (pasture