Tillage and soil type effects on soil surface roughness at semiarid climatic conditions

Soil surface roughness is an excellent index of soil susceptibility to wind and water erosion. For arid climatic conditions found in Central Spain, three types of tillage tools (roller, chisel and tiller) were used to work three different soils (sandy clay loam from two different locations and sandy loam from one location), to compare their effect on soil surface roughness. A pin meter was developed to measure soil roughness, based on its adaptability to field conditions. Soil micro-relief indexes were also developed for the interpretation of the data, based on the standard deviation (S.D.) and the coefficient of variation (CV). Structure and heterogeneity of the soil surface were expressed using CV and S.D. values for the data, along with a multifractal analysis, namely the f(α)-singularity spectrum. The field measurements were taken during 2005 under extreme drought conditions for Spain, namely an annual rainfall of 125 mm with a recurrence of once in 100 years. For the different soils and tillage tools, the indexes obtained agreed with the soil surface roughness expected from the different treatments (soil type-tillage tool). The statistical indexes of CV and S.D. provide a good interpretation of the soil surface roughness when provided with a complementary study of the soil structure and complexity estimated from multifractal analyses.