Understanding of the characteristics of soil organic matter (SOM) and soil nutrients at the field
and catchment scale is important for refining agricultural management practices and for improving
sustainable land use. In order to analyze on SOM and nutrient differences among different land use
types and their relationships between land use, landscape position and slope aspect, 94 sampling sites
including 7 land uses were selected along 6 transects in the Danangou catchment with an area of 3.5
km2 on the Loess Plateau of China. Significant differences in SOM, total N (TN), available N (AN)
and available P (AP) among these land uses were found. Higher values in SOM, TN and AN were
measured in soils from woodland and grassland, but lower values in the soils from fallow land and
cropland. Compare SOM and TN with cropland, intercropping land had high contents. The adjusted
R2 values of regression models for SOM and nutrients with land use, landscape position and slope
aspect ranged from 0.501 (SOM) to 0.134 (AP). A comparison between average predicted and
measured values for SOM and each soil nutrient revealed that the predicted values in TP and AN for
each land use, in SOM and TN except for fallow land and in AP except for intercropping land, shrub
land and woodland, fell with in a 95% confidence interval about the measured values. The simplified
predicted models of soil nutrients combined with the key value of SOM for soil quality can serve to
improve agricultural practices and to provide useful information on sustainable land use.
Improvement in SOM and nutrients would be expected from more C inputs including manure and
crop residues and alternative cultivation practices such as developing intercropping system, building
terrace for soil and water conservation, return the cropland with SOM content less than a key value
of 0.44% to the grassland and woodland on the hilly areas similar to the Loess Plateau of China. At the same time, it is recommended that nitrogen fertilization addition could be decreased in the foot
slope and increased on the upper slope