Surface roughness and wind erosion in soils of Semiarid Pampas of Argentina

DE ORO, LAURA A; BUSCHIAZZO, DANIEL E

CENPAT, Puerto Madryn, Chubut

Workshop; Multidisciplinary workshop on Southern South American Dust; 2007

CENPAT - CONSEJO NACIONAL DE INVESTIGACIONES CIENTIFICAS Y TECNICAS

Abstract Wind erosion is an important soil degradation process in semiarid regions. The soil surface roughness is one of the most important soil parameters in controlling this process. Wind erosion prediction models include the soil roughness as a central parameter within their soil subroutines. Successful estimates of soil erosion require accurate descriptions of the soil surface conditions produced by tillage operations and their degradation rates produced by weather conditions, mainly rains. Considering the importance of soil roughness in controlling wind erosion, experiments are carried out in the semiarid Argentina in order to measure the effect of soil roughness on wind erosion. This study is carried out in the following steps: 1) the effect of tillage practices on random and oriented roughness 2) the effect of rains on the degradation rates of soil roughness, and 3) the relationship between soil roughness and wind erosion. For these studies measurements of soil roughness and wind erosion are carried out in the field and under controlled conditions with a portable wind tunnel. The degradation rates of soil roughness are studied by means of a rain simulator. Preliminary results shows that the degradation of soil roughness measured in the field do not agree with predictions made with the existing models, because models are less sensitive. The oriented roughness (Kr) is more sensitive to the effect of rains than the random roughness and its degradation rate is strongly influenced by its initial values: the higher the initial soil roughness the smaller the degradation rate. This study also included the calculation of the threshold wind velocity (ìt) for annual and seasonal series of wind data obtained in the field. Results of this study showed that ìt values were similar in all analyzed years (2003-2005) and seasons, indicating that conditions to erode the soil during the whole analyzed period were homogeneous. This also demonstrates that a unique mean annual value of ìt (6.68 m s-1) can be used in wind erosion prediction models to be utilized in the Semiarid Argentina.