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本文根据Fick定律导出在耕作半径内土壤肥力必然会产生分化现象,并提出了以聚落为中心的土壤肥力呈同心圆分布的结构模型:F_r=F_0e~(kr)。Fr是离聚落,,处的土壤肥力水平,F。是近聚落中心的土壤肥力水平,K是肥力梯度或称Clark梯度。文中根据长江三角洲江苏省扬中县数千地块的平均统计资料,证明上述指数模型比线性模型更适合描述农田土壤肥力的分布,从而得到了和Clark人口分布法则完全一致的数学表式,进一步论证了农田土壤系统的空间耗散结构和土壤肥力的人口定律。文中广泛引用了苏北、皖北和四川省成都平原等地的土壤肥力分布资料,说明农田土壤肥力分布同心圆性的普遍性,并指出随着土壤系统生态经济结构的改变,数学模型也随着改变,但只有借人工从外界输入大量补助能量条件下,才有可能消除Clark梯度。此项研究是耗散结构理论在土壤肥力研究中的具体应用。
According to Fick’s law, the soil fertility will inevitably lead to differentiation in the farming radius. A structural model of concentric distribution of soil fertility centered on settlements is proposed: F_r = F_0e ~ (kr). Fr is the level of soil fertility at the settlement, F. Is the soil fertility level near the settlement center, and K is the fertility gradient or Clark gradient. According to the average statistical data of thousands of plots in Yangzhong County, Jiangsu Province in the Yangtze River Delta, it is proved that the above index model is more suitable than the linear model to describe the distribution of farmland soil fertility, and thus the mathematical formula exactly consistent with the population distribution law of Clark is obtained. The Population Law of Spatial Dissipation Structure and Soil Fertility of Farmland Soil System. In this paper, the soil fertility distribution data of northern Jiangsu, northern Anhui and Chengdu Plain of Sichuan Province are widely used to illustrate the universality of concentricity distribution of farmland soil fertility. It is pointed out that with the change of ecological and economic structure of soil system, The change, but only by labor input from the outside world under a lot of subsidies energy, it is possible to eliminate the Clark gradient. This study is the application of dissipative structure theory in the study of soil fertility.