Rice Yield and Nutrient Removal Through Harvest in Newly Developed Lowland Rice Field in Bulungan District, North Kalimantan

. Nutrient removal through rice harvest of Ciherang variety planted in newly developed lowland rice field was studied in Bulungan District, in 2013. The aims of this research were to evaluate the amount of nutrients taken out by rice harvest and to properly manage its fertility to sustain high rice yield. Five treatments were tested, T0: Farmers practices, T1: Package A (NPK at recommendation r ate + Dolomite), T2: Package B (NPK at recommendation rate + dolomite + Compost + Smart), T3: Package C (¾ NPK at recommendation rate + Compost + Dolomite + Smart), and T4: Package D (NPK at recom-mendation rate + Compost + Dolomite + Smart). They were arranged in a Randomized Complete Block Design and replicated three times. The results showed that the highest rice biomass yield (rice grains, rice straw and rice residues) was from the package D, whereas, the highest concentrations of N, P, and K were found in rice grain of Package B. The highest nitrogen and phosphorous removals were from rice grains and for potassium was from rice straw. Depending on the treatments, total nutrient removal through rice grains and rice straw varied: from 30.96 ± 2.93 to 67.82 ± 8.93 kg of N; 12.83 ± 2.15 to 27.53 ± 14.11 kg of P; and 55.10 ± 2.92 to 101.84 ± 6.02 kg of K ha-1 season-1. To avoid nutrient mining and to maintain the soil fertility, about 67 to 150 kg urea, 65 to 140 kg SP-36 and 105 to 196 kg KCl ha-1 season-1 should be applied to the soil