Submitted to: Acta Geologica Hispanica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2000
Publication Date: N/A
Interpretive Summary: Soil erosion is a process of detaching soil from one area, transporting, and then depositing the soil in another location. During the soil erosion process, soil properties within the eroding area and the depositional area will change, which in agricultural production fields alters the crop producing capacity of the land. Total soil erosion from a cultivated and non-cultivated site was determined using Cesium 137 measurements, a radioactive isotope from nuclear bomb testing in the 1950s and 60s. Water and tillage erosion estimations were determined by using computer-modeling techniques based on observed Cesium 137 redistribution within the respective sites. Soil quality measurements including soil physical and chemical properties were measured along with the Cesium 137. Results from this analysis showed that changes in soil quality over short distances (60 to 100 feet) could be related to soil erosion by water and soil deposition by tillage. Changes in soil quality over longer distances (greater than 200 feet) were best related to deposition by water and soil erosion by tillage. Land use associated with vegetative cover (cultivated versus non-cultivated sites) changes both the magnitude and distribution of the spatial patterns. The processes of soil loss by water erosion and soil deposition by tillage erosion were the main causes of variability in crop production potentials along field transects. Producers and conservation farm planners can use these data to explain field variations and to develop farm management plans to reduce this variation resulting in more efficient use of agricultural inputs.
Technical Abstract: Soil erosion rates and soil quality indicators were measured along two hillslope transects in the Loess Plateau near Yan'an, China. The objectives were to: (a) quantify spatial patterns and controlling processes of soil redistribution due to water and tillage erosion, and (b) correlate soil quality parameters with soil redistribution along the hillslope transects for different land use management systems. Water erosion data were derived from **137Cs measurements and tillage erosion from the simulation of a Mass Balance Model along the hillslope transects. Soil quality measurements, i.e., soil organic matter, bulk density and available nutrients, were made at the same sampling locations as the **137Cs measurements. Results were compared at the individual site locations and along the hillslope transect through statistical and applied time series analysis. The results showed that soil loss due to water erosion and soil deposition from tillage are the dominant soil redistribution processes in range of 23-40 m, and soil deposition by water erosion and soil loss by tillage are dominant processes occurring in range of more than 80 m within the cultivated landscape. However, land use change associated with vegetation cover can significantly change both the magnitudes and scale of these spatial patterns within the hillslope landscapes. There is a strong interaction between the spatial patterns of soil erosion processes and soil quality. It was concluded that soil loss by water erosion and deposition by tillage are the main causes for significant scale dependency of spatial variability of soil quality along hillslope transects.