Effect of rainfall on the variation in water reserves of cultivated soils in the Tunisian semi-arid zone. [French]Original Title Effet de la pluviometrie sur la variation des reserves hydriques des sols cultives en zone semi-aride tunisienne.

摘要

Water contents were monitored on two soils with differing morphological and physiochemical properties over two cropping systems. These soils were treated by the same farming techniques and were sown with durum wheat (Triticum durum) during 2009 and field bean (Vicia faba minor) during 2010. The highest rainfall event in 2009 recharged the water in the soil in the lower plains, but the evapotranspiration rate of the wheat crop exceeded the rainfall and the ETM calculated on the basis of temperature data and crop-factors. The lower horizons of this soil contributed to the water supply of the crop which was in contrast to those soils in the hillside positions where water was consumed in the 0- to 60-cm layer. Water consumption in the hillside soils was lower than the water consumption in the soils located in the plains. The capacity of the soil in the lower plains to provide additional water to the crop resulted in higher productivity as evidenced by the 700 kg ha-1 increase in grain yields compared with the soils on the hillside. When drought periods occur, such as in the 2010 field season, water is retained at the higher soil matric potential and the crop experienced water stress in both soils. Under these conditions, the lower soil horizons in the soils located in the plains do not provide as much water as the they would in wetter years; however, they do benefit from the water contribution from the upper slope positions.