论文部分内容阅读
A 15N-tracing study was conducted to investigate the gross N transformation rates involved in the production and consumption of NH4+and NO3-in karst region soils(a calcareous and a red soil)from southwest China under woodland.The gross mineralization rate of organic N to NH4+was much lower in calcareous soil(3.71 mg N kg-1 d-1)than in red soil(5.57 mg N kg-1 d-1),while the total gross nitrification rate was significantly higher in calcareous soil(5.80 mg N kg-1 d-1)than in red soil(0.70 mg N kg-1 d-1).Microbial NO3-immobilization accounted for 2.9%and 153%of the total nitrification in calcareous soil and red soils respectively.Thus the calcareous soils in the karst region have a low biological N retention capacity and high N losses,which are further aggravated by the high precipitation and fractured soil structure.