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

Abstract

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 m s À1 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 À1 was measured. Half of the sediment loss occurred during a single, 12-day period. Deposition of 26·5 Mg ha À1 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.

Erosion, Suspended Sediment Transport and Sedimentation on the Wadi Mina at the Sidi M’Hamed Ben Aouda Dam, Algeria

“…Small changes in precipitation can have significant impact on the flow of surface water [145]. In fact, climate is recognized to be the main factor in semi-arid Mediterranean areas of Algeria which experience short and intense rain episodes, high evaporating power of wind, prolonged droughts and freezing and thawing cycles [42,45,46].…”

Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)

“…Amongst the factors favouring erosion (slope, nature of rocks, relief, climate, human activities), climate is recognized to be the main factor in semi-arid Mediterranean areas of Algeria which experience short and intense rain episodes, high evaporating power of wind, prolonged droughts and freezing and thawing cycles (Touaibia, 2010;Houyou et al, 2014). Erosion is extremely active and the average concentration is at least 1 order of magnitude higher than the global average (Achite and Ouillon, 2007).…”

Impact of land management system on crop yields and soil fertility in Cameroon

“…Sorghum was intercropped with Brachiaria ruziziensis, also called Congo grass. It is a forage crop that is grown throughout the humid tropics (Husson et al, 2008;Naudin, 2012). It requires well-drained soils with low clay contents, moderate to high fertility and does not tolerate strong acidic conditions.…”