Full Length Research Paper
Adel Belhassen
Abstract
Highly weathered soils and potential acid sulphate soils in Indonesia are mainly granted for developing newly opened wetland rice field to meet rice growing demand. Nutrient removal by rice harvest product of Inpari 10 variety planted in newly opened wetland rice was studied in Bulungan District, in 2011. The aims were to study the nutrient taken out by rice harvest product and to manage its fertility status to sustain rice farming. The results indicated that the highest concentrations of N, P, and K in rice grain and rice straw were observed at NPK recommended rate, in which P was split two times (T6). The T6 also showed the highest nutrient removal by harvest product. Depending on the treatments, total nutrients removal through rice grains and rice straw varied from 37.25 and 93.75 kg N, 2.99 and 8.49 kg P, 53.03 and 149.03 kg K ha-1 season -1 , meaning that at least about 83 to 208 kg urea, 19 to 53 kg SP-36 and 103 to 289 kg KCl ha-1 season -1 should be given to replace nutrient removed by harvest product and to avoid any nutrients depletion. As recently the spirit of Indonesian rice farming is applying more organic fertiliser, to sustain better rice yield, the fertiliser application rate of 200 kg urea, 75 kg SP-36 and 200 kg KCl ha-1 season -1 plus 3000 kg compost made of rice straw and 2000 kg dolomite ha-1 season -1 can also be recommended.