Improvement of Soil Fertility and Crop Production through Direct Application of Phosphate Rock on Maize in Indonesia

Most of Indonesian agricultural soils are acidic and low in both total and available phosphorus particularly. The major nutrient constraint in these soils is P and responses to both N and K are poor unless P deficiency has first been corrected. Correction of P deficiency therefore constitutes a major part of improving fertility of acid soils. Phosphate rock is recommended for application to acid soils where phosphorus is an important limiting nutrient on plant growth. This problem faces most acid soils in Sumatra and Kalimantan.We conducted a study of the effect of reactive phosphate rock for Maize on an Ultisol in Pleihari, South Kalimantan Province. The experiment was carried out in farmer fields for six cropping season. The objectives are to evaluate direct application of reactive phosphate rock (RPR) for Maize, its combination with manure and agronomic effectiveness. Reactive phosphate rock improved soil fertility and maize crop productivity. Moroccan RPR contained the highest citric acid extractable P2O5 among other phosphate rock tested and also the most effective in improving maize yield. In addition, the residual effect of phosphate rock in supplying plant with P for up to six cultivation years was demonstrated. However, although phosphate rock is cheaper than SP-36, farmers did not adopt this technology yet.Through collaboration research between The OCP and ISRI (Indonesian Soil Research Institute), a more comprehensive study on the potential effect of direct application of Reactive Phosphate Rock from OCP MOROCCO, on Maize is being conducted. The overall objectives are to evaluate direct application of Reactive Phosphate Rock for Maize and find out the best application rate and method of Rock Phosphate for Maize.