The nutrient status of two soil forms of the Orange River development project

Mainly two types of soil viz. the red sandy soils (Hutton form) and the yellow sandy soils (Clovelly form) were recommended by Van Rooyen (1965, 1967) for irrigational purposes under the Orange River Development Project. Fifteen soil profiles, comprising these two soil forms, were analysed for calcium, magnesium, potassium, sodium, phosphorus, sulphur, copper, zinc and manganese. A pot experiment, including a representative sample from each soil form and different levels of potassium and phosphorus, was conducted to test the reactions of these soils to phosphorus and potassium applications. Phosphate potential studies were conducted on selected samples from each soil form. These soils were found to be deficient in phosphorus, potassium, copper and zinc. A difference in the reaction of these soils to applied phosphorus and potassium was indicated. An extremely interesting relationship between the resin-P-content and phosphate potentials of these. soils was found.