丘陵红壤蔗区土壤有机质的时空变异特征

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

采用地统计学和GIS相结合的方法，研究了甘蔗连作19年（1980～1999年）的低丘陵红壤蔗区土壤有机质含量的时空变异特征。研究结果表明：由于土壤侵蚀和土地利用格局的影响，1980年的土壤有机质与地形坡度为极显著负相关。在长期甘蔗连作下，地形坡度对1999年的土壤有机质空间分布已没有影响，而有机肥施用的侧重方向使得土壤有机质与经纬度、海拔高度都有相关性。土壤有机质的时空变异与蔗区耕作管理的精细化程度有关，精细化程度高的高产蔗区的土壤有机质平均降幅为11％，而精细化程度低的低产蔗区土壤有机质则平均增幅为50％。大量施用源自甘蔗的有机肥已造成蔗区土壤兼分的不平衡。

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.