Sukristiyonubowo, Fadhli Y. and A. Sofyan
Developing of newly opened wetland rice is one of the Indonesian major concerns to meet the rice growing demand, keep food security and generate farmers’ income. Study on plot scale nitrogen balance of newly opened wetland rice conducted in Panca Agung village, Bulungan District, East Kalimantan in 2009 was not only to validate the nitrogen fertilizer application rate, but also to provide nitrogen fertilizer during planting season and to sustain rice production. Nitrogen balance was computed according to the differences between nitrogen gains and losses. The results indicated that positive nitrogen balances were taken place in all treatments meaning that surplus nitrogen fertilizer application. Economically and environmentally was considered high cost and caused water pollution. Application of rice straw compost was not only contributed to nitrogen inputs and other nutrient, but also may create better soil condition for microbial activity. To avoid any negative impacts, in term of environmental, agronomical and economic point of views, the recommended urea application rate should be reduced from 250 to 200 kg ha-1 season-1 with adding compost of about 3000 kg ha-1 season-1.
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