UREA HYDROLYSIS AND UREASE ACTIVITY IN SAUDI ARABIAN SOILS

Soil samples were collected from eight different localities in Saudi Arabia, and analysed for mechanical properties as well as for urea hydrolysis. The urease enzyme activity of these calcareous soils was also investigated. Urea applied (10 mg urea - N/g soil) was almost totally hydrolysed to ammonia in all soils tested within four weeks. The addition of urea to soils led to a marked increase in the concentration of NH/ in most soils. The maximum amount of NH/ was recorded in Alkharj soil (4.0 mg/g soil), a site which exhibited the highest activity ofurease enzyme (85 µg Urea/g/h).