|Van Pelt, Robert - Scott|
Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2008
Publication Date: 11/15/2008
Citation: An, S., Zheng, F., Zhang, F., Van Pelt, R.S., Hamer, U., Makeshin, F. 2008. Soil quality degradation processes along a deforestation chronosequence in the Ziwuling Area, China. Catena. 75(3): 248-256. Interpretive Summary: As world population increases, more food and fiber must be produced to meet increasing demands. Soil degradation results from many processes associated with poor management. Changing land use from forest to cultivation results in the loss of soil cover and the increased oxidation of soil carbon. If the land is sloping or subject to high velocity winds, loss of topsoil due to erosion may further degrade the soil’s productivity. Understanding the processes responsible for soil degradation is important if we are to prevent, retard, or reverse the damage. We looked at a chronosequence of soils that had been cleared of secondary growth forest and cultivated to measure the loss in soil quality as a function of time, make inferences about the processes responsible for the degradation, and to look for convenient measures of soil quality in this region of Asia.
Technical Abstract: Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence of deforestation in the Ziwuling area of northwestern Shaanxi province. The results indicated that soil wet aggregate stability and mean aggregate diameter decreased with years following deforestation. Accelerated erosion resulted in soil nutrient loss, including notable losses of total soil N, organic C, and a decrease in soil enzyme activities including alkaline phosphatase activity and invertase activity. During the early time period, the rates of total soil N, organic C, alkaline phosphatase activity, and invertase activity decrease were rapid and the rate gradually decreased with deforestation years. Increased use of nitrogen fertilizers made determination of soil quality based on measured NO3-N and NH4-N inconclusive. The differences in measured parameters between the topsoil and subsoil horizons decreased with time since deforestation, and we concluded that soil erosion was the primary process responsible for the degradation of measured soil physical, chemical, and microbiological properties.