Nitrogen releases from sewage sludge amended soils
2001
Prapit Sangtong(Department of Agriculture, Bangkok (Thailand). Soil Science Div.) | Bhavana Likhananont(Department of Agriculture, Bangkok (Thailand). Soil Science Div.)
Nitrogen availability from sewage sludge amended soils was studied in laboratory. Two soils: Rangsit and Pakchong series were incubated with wet and dry sludge at 3 application rates (0.25, 0.5 and 0.75 percent C) for 12 weeks at room temperature. Soil water contents were maintained at around 60 percent water holding capacity. Inorganic N in these 2 soils were increased with increasing rate and prolonging time of incubation. The significantly marked increases of available N were found at the highest rate of sewage sludge application due to very high N mineralization with time. This high N mineralization might be caused by the addition of easily degradable and thus sewage sludge and soil organic matter. However, addition of sludge at high rate induced N loss through volatilization of NH3 and N20 as reflected by the lower rate of N mineralization. Lastly, application of sewage sludge increased soil fertility as observed by the increase of organic matter content by 0.5 times in Rangsit soil and 4 times in Pakchong soil .
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