Nitrogen transformation from three soil organic amendments in a sandy soil

摘要

A sandy soil was amended with various rates (20 - 320 g air-dry weight basis of the amendments per kg of air-dry soil) of chicken manure (CM), sewage sludge (SS), and incinerated sewage sludge (ISS) and incubated for 100 days in a greenhouse at 15% (wt/wt) soil water content, At the beginning of incubation, NH4-N concentrations varied from 50-280 mg kg~(-1) in the CM amended soil with negligible amounts of NO_3-N. Subsequently, the concentration of NH_4-N decreased while that of NO_3-N increased rapidly, In soil amended with SS at 20-80 g kg~(-1) rates, the NO_3-N concentration increased sharply during the first 20 days, followed by a slow rate of increase over the rest of the incubation period, However, at a 160 g kg~(-1) SS rate, there were threedistinct phases of NO_3-N release which lasted for 160 days. In the ISS amended soil, the nitrification process was completed during the initial 30 days, and the concentrations of NH_4-N and NO_3-N were lower than those for the other treatments. The mineralized N across different rates accounted for 20-36%, 16-40%, and 26-50% of the total N applied as CM, SS, and ISS, respectively.