Evidence of Strong Land Degradation by Wind Erosion as a Result of Rainfed Cropping in the Algerian Steppe: A Case Study at Laghouat

In Algeria, overgrazing has long threatened the sustainable use of the nearly 20 million hectares of steppe lands. More recently, governmental policies favouring extensive rainfed cereal cropping in the steppe region have increased anthropic pressure on this fragile environment. Low rainfall, weak crop development and sandy soils lead to a high risk of wind erosion, yet no studies have been carried out in this region to this date to quantify the effect of steppe conversion on wind erosion. A 1.3-ha field in the central steppe of Algeria (Laghouat) was converted to cropland (Hordeum Vulgare L.) and equipped with a weather station and Big Spring Number Eight sand straps to monitor climate-related parameters and sediment fluxes over a 25-month period. Threshold wind velocities (3.6 m height) varied between 6 and 7 ms(-1) with a weak seasonal variation. More than 70% of the saltation-producing winds originated from the NW. For these winds, a soil loss of 155 Mg ha(-1) was measured. Half of the sediment loss occurred during a single, 12-day period. Deposition of 26.5 Mg ha(-1) was observed for SW winds. The measured erosion rates by far exceeded all norms of tolerable soil loss, indicating that rainfed cereal cropping is a highly unsustainable form of land use in the steppe region around Laghouat. National agricultural policies should be revised to take this into account. (c) 2014 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd.