Characteristics of the spatio-temporal changes of soil organic matter of sugarcane field in red soil hill areas

Temporal and spatial changes of soil organic matter(SOM) content in the sugarcane field after 19-year interval(from 1980 to 1999) were evaluated using geostatistics and geographic information system(GIS). Results show that there are negatively significant correlation between the slopes of terrain and SOM content in 1980, as a result of soil erosion and land use pattern changes. The slopes of terrain do not have obviouse impact on the spatial distribution of SOM content in 1999 under long-term sugarcane monoculture. There are significant correlations among the elevation, lattitude, longitude and SOM contents due to the stress direction when applying organic manures. The spatio-temporal changes of SOM content are related to the degree of intensive cultivation. The SOM content of the higher yield fields with high degree of intensive cultivation decreases 11% on average, while the SOM content of lower yield fields increases 50% on average under low degree of intensive cultivation. Lots of sugarcane-derived organic matter has already caused soil nutrition imbalance.