Morphology and composition of some soils under cultivation in Saudi Arabia

Twelve profiles representing the principal soils of five major agricultural areas (Al-Kharj, Gassim, Hofuf, Taif and Wadi Dawasir) in Saudi Arabia were described and sampled by horizons. Laboratory analyses were then made of the samples to characterize the profiles more completely. Analyses were also made for certain nutrient elements to get some measure of their levels in the soils.The profiles are tentatively classified in the Entisol and Aridisol orders of the American taxonomy. Five Entisol profiles were considered to be Fluvents and two Psamments. Four Aridisol profiles were considered to be Argids and one an Orthid.All of the profiles are saline and calcareous and most are also sandy. Furthermore, amounts of nutrient elements such as phosphorus, iron and zinc in surface layers are below minimum levels established for similar soils in earlier investigations in other countries. Consequently, the soils are believed to lack sufficient quantities of several elements for optimum plant growth. Successful use of the soils will thus require reductions in salinity, increased levels of nutrient elements, and skillful irrigation to provide adequate moisture.