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.