Phosphate rock (PR) is used almost exclusively as P fertilizer for perennial crops in Malaysia. This is attributed to its rapid P dissolution and high P sorption capacity under the high rainfall and acidic soil conditions in the country. It is, of course, also cheap. For decades, Christmas Island Rock Phosphate (CIRP) was the main PR used, until a hiatus in its production in 1987 allowed the entry of other P. The P responses by mature oil palm to CIRP have been well studied. The effectiveness of the fertilizer on crop performance depends not only on its inherent characteristics, but also on the chemical reactions between the P fertilizers and the soils to which they are applied and their physical factors. However, studies on the other PRs, particularly the reactive ones, are rather limited. In view of their different effectiveness on oil palm, a field evaluation was conducted on commercially available PRs, and the results reported here. 

Main Research: Dr Zin Zawawi Zakaria