Resources Science ›› 2019, Vol. 41 ›› Issue (4): 753-765.

### Scale effect of soil fertility spatial variability and its influencing factors

GE Chang1, LIU Huilin1, NIE ChaoJia1, SHEN Qiang2, ZHANG Shiwen1

1. 1. Earth and Environmental Sciences, Anhui University of Science and Technology, Huainan 232001, China;
2. Faculty of Surveying and Mapping, Anhui University of Science and Technology, Huainan 232001, China
• Received:2018-06-27 Revised:2018-11-02 Published:2019-04-25

Abstract: In order to reveal the spatial variability of regional soil fertility and its influencing factors, and their change with scale, this study took Pinggu District of Beijing Municipality as the study area, and examined soil fertility and varibility at three spatial scales — the whole district (large), three towns in the western part of the district (medium), and dense sampling in the same three twons (small). The soil Integrated Fertility Index (IFI), which was calculated by the weighted sum method, was used for the characterization of soil fertility. Combined with the methods of variation function and geographically weighted regression (GWR), the spatial variability characteristics of IFI, the contribution degree of each evaluation indicator to soil fertility, and the scale effect were analyzed. Difference of the influencing factors of soil fertility at different scales were identified and characterized. The results show that the difference of soil fertility influencing factors at different spatial scales was obvious, while IFI was around 0.61 at all three scales, and the CV ratio changes of IFI between different scales were different compared to other indicators. The spatial variability of IFI illustrated a significant scale effect. The C0/Sill of IFI increased with the decrease of scale and the proportion of variation caused by random factors increased gradually. IFI showed a strong spatial correlation at the large scale, moderate spatial correlation at the medium scale, and weak spatial correlation at the small scale. The contribution of different soil nutrient contents to IFI varied at different scales. From the large to the small scale, the nutrient coefficients exhibited a decreasing trend, and the range of nutrient coefficients increased slightly from medium to small scale. The effect of a soil property on IFI will be affected by other properties. Factors such as soil subclass and parent material had an obvious scale effect on IFI. As the scale decreases, the influence of various factors on IFI decreased generally. The results provide a technical support for regional soil fertility evaluation and spatial pattern analysis at different scales.