However, soil aggregates were not similarly
affected by water. Aggregates in CAS were the least stables and more
susceptible to disruption with MWD2 treatment (mechanical breakdown
test), suggesting that disintegration of aggregates in CAS can
mainly be explained by the low cohesive forces between particles on
the periphery of aggregates. Conversely, the three tests only slightly
contribute to disintegration of soil aggregates sampled in FAL, BRA,
EUC and FOR and they were mostly affected by MWD1 (fast-wetting
test). Hence, we assume that the main mechanism of aggregate
disruption in these ecosystems was the slaking after compression of
air entrapped inside aggregates. The greater aggregate resistance in
FAL, BRA, EUC and FOR may be due to increased binding and gluing of
aggregates by SOM, and especially polysaccharides (Molope et al.,
1987; Chenu et al., 2000; Malam Issa et al., 2001).