Spatial Prediction of Soil Total Phosphorus in a Karst Area: Comparing GWR and Residual-Centered Kriging

Laimou Lu, Penghui Li, Liang Zhong, Mingbao Luo, Liyuan Xing and Chunlai Zhang ()
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Laimou Lu: Key Laboratory of Coupling Process and Effect of Natural Resources Elements, Beijing 100055, China
Penghui Li: Key Laboratory of Karst Dynamics, Ministry of Natural Resources and Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China
Liang Zhong: Key Laboratory of Karst Dynamics, Ministry of Natural Resources and Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China
Mingbao Luo: Agriculture and Rural Affairs Bureau of Mashan, Nanning 530600, China
Liyuan Xing: Key Laboratory of Coupling Process and Effect of Natural Resources Elements, Beijing 100055, China
Chunlai Zhang: Key Laboratory of Karst Dynamics, Ministry of Natural Resources and Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China

Land, 2024, vol. 13, issue 12, 1-14

Abstract: Accurate soil total phosphorus (TP) prediction is essential to support sustainable agricultural practices and formulate ecological conservation protection policies, particularly in complex karst landscapes with high spatial variability and high phosphorus and cadmium content and interactions, complicating nutrient management. This study uses GIS and geostatistical methods to analyze the spatial distribution, influencing factors, and predictive modeling of soil TP in the karst region of northern Mashan County, Guangxi, China. Using 427 surface soil samples, we developed five predictive models: ordinary kriging (OK), regression kriging (RK) and geographically weighted regression kriging (GWRK) combined with environmental variables such as land uses, soil types, and topographic factors; residual mean-centered kriging (MM_OK), and residual median-centered kriging (MC_OK). Our results indicate that higher TP levels were observed in agricultural lands (paddy fields and dry land, at 766 and 913 mg·kg −1 , respectively) may due to fertilization, while forests and shrublands showed lower TP levels (383 and 686 mg·kg −1 , respectively), reflecting natural phosphorus cycling. The high-value areas of soil TP concentration are in the karst areas in the west and east of the study area, and the low-value area is in the Hongshui River valley in the north of Mashan. The spatial distribution of soil TP is affected by land use, soil type, and topography. The GWRK model exhibited superior accuracy (80.6%), with predicted concentration of TP closely aligning with observed TP values, effectively capturing fine spatial variations, and showing the lowest mean standardized error, average standard error, and mean absolute error. GWRK also achieved the highest R 2 (0.67), demonstrating robust predictive capability. MM_OK and MC_OK models performed well and showed smoother spatial transitions, while the OK model displayed the lowest predictive accuracy (62%). By utilizing spatially adaptive weighting, GWRK and its residual-centered kriging method improve soil TP’s prediction accuracy and smoothness in karst areas, providing a reference for targeted soil conservation and sustainable agricultural practices in spatially complex karst environments.

Keywords: karst; geographically weighted regression; soil total phosphorus; spatial variation; land use; residual-centered kriging (search for similar items in EconPapers)
JEL-codes: Q15 Q2 Q24 Q28 Q5 R14 R52 (search for similar items in EconPapers)
Date: 2024
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