Abstract

Study on management of inherent soil fertility of newly opened wetland rice for sustainable rice farming in Indonesia was conducted in Bulungan District, from 2009 to 2010. The aims were to know the soil fertility status and properly manage its fertility status to improve rice yield and sustain rice farming. Six treatments were imposed including T0: farmers practices, T1: farmer practices + compost + dolomite, T2: NPK recommended rate, N and K were split two times, T3: NPK recommended rate, N and K were split three times, T4: NPK recommended rate, N and K were split three times + compost + dolomite and T5: NPK recommended rate, N and K were split two times + compost + dolomite. The residual effect of dolomite and compost applied in 2009 was continually assessed in 2010. The results indicated that inherent soil fertility was categorised poor with high level of iron and manganese. Application of 250 kg urea, 100 kg super phosphate-36 and 100 kg potassium chloride ha^-1, in which N and K fertilisers were split three times plus 2 tons dolomite and 2 tons compost ha^-1 also the residual effect of dolomite and compost improved soil fertility, rice growth and biomass production.

Key words: Soil fertility, newly wetland rice, rice farming, dolomite, compost.