Soil surface roughness degradation by rainfall of two loess soils.

DE ORO, L.; BUSCHIAZZO, D.E.

Santa Rosa, Argentina

Congreso; ICARVII; 2010

Int. Soc. Aeolian Res.

Soil surface roughness, one of the driving factors of wind erosion, is affected by rains and tillage. Little is known about the influence of rains and tillage systems on the surface roughness of different textured soils. The purpose of this paper was to evaluate the dynamics of the oriented (Kr) and the random (Crr) soil surface roughness as affected by: a) three tillage tools: a disk tandem (DT), a lister-bedder (LB) and a drill-hoe (DH), b) two soil types (an Entic Haplustoll and a Typic Ustipsamment) and c) two rain amounts (7 and 28 mm). Measured Kr and Crr decay rates were compared with the predicted decay rates, using the equations of the Revised Wind Erosion Equation (RWEQ). Results indicated that the initial Kr values were different between tillage tools in both soils (LB > DH > DT, p< 0.05), while Crr values were mostly similar.  The degradation rate of Kr (ORR) was in general higher in the Ustipsamment than in the Haplustoll and in DT more than in DH and LB, in both soils. The degradation rate of Crr (RRR) was affected by soil type (mostly higher in the Ustipsamment than in the Haplustoll) but not by the tillage tool. Increasing rain amounts degraded Kr and Crr at higher rates in both soils, but Kr degraded at different rates depending on its initial value, when higher was initial Kr, degraded less (LB<DH<DT). The relative Kr decay (%) was higher in the Haplustoll than in the Ustipsamment, mainly for small initial Kr values. The equations obtained to the data of both soils were for the Haplustoll y= 41.33 x-0.71, R2= 0.86 (p<0.001) and y= 46.24 x-0.27, R2= 0.58 (p<0.001) for the Ustipsamment. The equations used by RWEQ underestimated the soil surface roughness decay of the studied soils. Because of that we proposed to relate Kr degradation with the amount of accumulated rains (in mm), using as a basis the initial Kr values.