SOIL organic matter, a major factor affecting agroecosystem stability, is controlled by many parameters. Itis well understood that cultivation practive would lead to a decrease in organic matter content of soils.However, small gradual changes in total soil organic matter may be difficult to monitor and detect in theshort term because of generally high background carbon levels and natural variability of soils. On ashort-term scale the measurement of the living fraction of soil organic matter, i.e. microbial biomass C,can reveal early changes in soil organic matter. Our work is to identify the relationship of soil organic Cand changes in microbial biomass C with sea-level elevation increasing. Twelve terrace fields on the slopes at different altitudes above sea level were chosen as sample localities. The terrace fields, different in size, approximately 10 m~2, were used for growing maize. Those sam- It is well understood that cultivation practive would lead to a decrease in organic matter content of soils. Small, small gradual changes in total soil organic matter may be difficult to monitor and detect in theshort term because of generally high background carbon levels and natural variability of soils. On ashort-term scale the measurement of the living fraction of soil organic matter, ie microbial biomass C, can reveal early changes in soil organic matter. Our work is to identify the relationship of soil organic Cand changes in microbial biomass C with sea-level elevation increasing. Twelve terrace fields on the slopes at different altitudes above sea level were were chosen as sample localities. The terrace fields, different in size, approximately 10 m ~ 2, were used for growing maize. Those sam-