Tillage effects on soil surface conditions and dust emission by wind erosion in semiarid Aragón (NE Spain)

Abstract

Wind erosion is one of the most serious soil degradation problems in many agricultural regions of the world. Due to particular soil and climate conditions and inappropriate agricultural practices, Central Aragón (NE Spain) is a semiarid region prone to land degradation by wind erosion. However, actual wind erosion data are not yet available. We report here results from a wind erosion study conducted during the summer 1995 within a single dryland field located in Central Aragón. Two consecutive field experiments investigated the effects of chisel ploughing (reduced tillage) and mouldboard ploughing (conventional tillage) on soil surface conditions and vertical dust flux. Micrometeorological data and suspended sediment samples were collected in the month following each tillage operation. Likewise, soil surface properties affecting wind erosion were determined immediately after tillage. Values of vertical dust flux varied from 0.52 to 5.03 μg m −2 s −1 (for a range of wind shear velocity of 0.46–0.56 m s −1) during the first experimental period (after chisel ploughing) and from 1.45 to 11.66 μg m −2 s −1 (for shear velocities between 0.37 and 0.72 m s −1) in the second experiment (mouldboard ploughing). The wind-erodible fraction of soil surface (aggregates<0.84 mm diameter) was 41% and 50% after chiseling and mouldboard ploughing, respectively. The percentage of soil cover with crop residues and clods was 15% after chiseling and only 4% after mouldboard ploughing. The frontal area of this nonerodible material and soil roughness was reduced four times after mouldboard ploughing. Although direct comparisons of tillage effects are still necessary, these first results suggest that reduced tillage, with chiseling as primary tillage, could be considered as a viable alternative for wind erosion control during the fallow period in semiarid Aragón. This study indicates, likewise, the need to consider the temporal and spatial variability of soil properties affecting wind erosion in agricultural soils.