A tilled soil has increased susceptibility to raindrop impact and sediment transport by laminar surface flow and splash, but after tillage the soil reconsolidates, increasing again its resistance. Thus, an experiment was conducted on a Hapludalf with Sandy loam soil surface, under no-tillage for eight years, to evaluate interrill erosion under different tillage methods. The experiment was totally randomized with six replicates. The treatments were recent conventional tillage (RCT), two-month consolidated conventional tillage (CCT), no-tillage with mulch (NTM) with 94% surface coverage, and no-tillage with bare surface (NTB). A constant rainfall of 65 mm h-1 was applied for 90 min. The plots had dimensions of 0.50 m by 0.75 m, with an average slope of 8.5%. The interrill soil erodibility (Ki) was 1.77 x 10(6) kg s m-4. Soil loss was similar for conventional tilled soil (RCT and CCT) and for no-tillage soil (NTM and NTB), but tillage increased soil loss seven-fold. The means weight diameter of aggregates was smaller for conventional than for no-tillage soil. Thus, soil loss was reduced and aggregate stability increased due to long consolidation (eight years) and to other effects of the no-tillage system. Presence of mulch on no-tillage soil reduced water loss rate by 31%. Thus, soil consolidation and surface coverage have complementary effects on reducing soil and water losses.
no-tillage; soil and water loss; erodibility; sediment size; surface sealing