杞麓湖盆地土壤有机质多时相空间分布与演变

基于四期土壤采样点数据，结合样点调查和统计年鉴数据，采用普通克里格、多元回归和探索性回归方法预测杞麓湖盆地土壤有机质（SOM）空间分布并分析其影响因素。结果表明指数和椭球模型分别较好地拟合了2008和2011年、2013和2015年的SOM的空间变异性。四个时相的SOM均由西南到中部再到东北部呈现出低-高-低的分布特征，并且高值核心区的位置不变，但高值区范围逐年扩大。前三个时间段内SOM连续增加的区域面积是连续减小的区域面积的两倍多。土壤亚类类型、农业设施和土壤质地各解释SOM变异的14.3%、2.6%和1.3%。SOM的降低主要由粮食和蔬菜的高产出所导致，适当地减少氮肥施用量并增加复合肥施用量能在一定程度上维持甚至提升SOM含量。

The Multi-Phase Tempo-Spatial Distribution and Variation of Soil Organic Matter in the Qiluhu Basin

Of the data of the sites for the four-round soil sampling, and the data gathered during the field survey of the sample sites and published in the statistical yearbook, ordinary kriging, multiple regression and exploratory regression were performed to predict spatial distribution of SOM in the Qiluhu Basin and to analyze its influential factors. Results show that the exponential model outperformed the spherical model in fitting the spatial variation of SOM in 2008 and 2011, while the spherical model behaved better in 2013 and 2015. In all the four time phases, the distribution of SOM showed a saddle-shaped curve, that is, low, high and low in content, going from the southwest to the center and then to the northeast in the area. Moreover, the peak stayed unchanged in position, while expanding in area year by year. During the first three time phases, the area with SOM keeping on increasing was twice as large as the area with SOM decreasing continuously. Soil subclasses, agricultural facilities and soil textures explained 14.3%, 2.6% and 1.3% of the variability of SOM, respectively. The decline in SOM content could be attributed to the increase in the yield of the cereal and vegetable crops. And the practice of properly reducing the application rate of nitrogen fertilizers and increasing that of compound fertilizers helped maintain or even raise the content of SOM in the area.