Causes of dryland formation
Limited rainfall, poor soil quality, fragile environments are the main factor behind dryland formation. There is always water scarcity in drylands. The dryness of drylands is due to negative balance between mean annual precipitation and potential evapotranspiration rates. Besides, limited rainfall, the soils are of poor quality, low in organic matter, hence less fertile. Harsh climates are another important issue which limits crop diversification in drylands. What makes the drylands a difficult environment is not only less rainfall, but also its erratic distribution. Inter annual rainfall can vary from 20-100 per cent and periodic draughts are common (Zurayk and Haider, 2002).
Problems of drylands
Water scarcity due to limited rainfall, low soil fertility, mostly deep sandy soil with poor water holding capacity, shallow and rocky soils with low organic matter content. Fragile environments with unpredictable floods and droughts are other factors limiting drylands to become productive ecosystems. Lack of technologies limitation of resources and biotic pressures contribute further in conversion of drylands into deserts.