Malaysian soils are highly weathered, acidic, and not very fertile for crop production. About 75" of these soils fall under the Ultisols and Oxisols soil group, which are normally found in tropical regions. Ultisols are usually acid soils, which have been formed under forest vegetation and are not natively fertile. Different types of soils are found in whole Malaysia. Organic soil in Malaysia is divided into nine main classes based on the problems concerned with the soil and management steps. Most of these soils are poorly drained, have low fertility, and require high cost of construction. Ultisols and Oxisols in Malaysia contain 1"–2" organic matter, which is not sufficient for plant growth. Most of these soils are cultivated under oil palm, rubber, and cocoa. Oil palm is the most important agricultural crop in Malaysia. The main sources of phosphorus in oil palm plantation are phosphate rocks (PRs), triple superphosphate (TSP), and diammonium phosphate (DAP).