Study on Relationships between Biomasses of Present Secondary Plant Community and Soil Fertility Conditions in Loess Plateau

The relationships between the biomasses of secondary plant community and the soil fretility factors were studied with site types in gully region in Loess Plateau. The results are as follows:(1)The mean biomass of plant community on all kinds of site types is 1.045 kg/m2;(2)The main content of soil organic matter, in 0～30 cm soil layer, is 24.15 g/kg on northern gully slop, and is 14.26 g/kg on southern gully slop. There are remarkable linear relationships between the soil organic matter contents in 0～30 cm and in 0～60 cm soil layers and ground biomasses of plant community. The linear regression equations are y=9.7+17.2x (r=0.66) and y=6.9+11.7x (r=0.62). The idea, using ground biomass of plant community to estimate the soil organic matter content, is right. The relationships between soil nitrogen contents and ground biomasses of plant community need to be studied further.