Purpose To investigate the spatial heterogeneity and driving factors of soil pH and heavy metal chromium (Cr) content in tea plantations in plateau mountainous areas, providing a scientific basis for high-yield and high-quality tea cultivation.
Methods Soil samples from 423 tea plantations in Guiding County, Guizhou Province were collected. Geostatistics and semivariance function models were used to explore the spatial heterogeneity of soil pH and Cr in the tea plantations. Random forest algorithm was used to study the driving factors of Cr content variations under different pH conditions.
Results 74% of soil samples in plateau mountainous tea plantations had a pH value between 4.5 and 6.0, suitable for tea cultivation. The Cr content in the soil was within safe levels. The soil pH value decreased gradually from southwest to northeast, showing a clear zonal distribution. The spatial distribution of soil heavy metal Cr decreased gradually from north to southeast, with low-value patches mostly appearing in the southeast and high-value patches concentrated in the central-western region.
Conclusion Different soil pH values have varying impacts on Cr content. In tea plantation soils with pH≤5.5, soil pH has the greatest impact on Cr content; in soils with 5.5<pH≤6.5, soil particles have the greatest impact on Cr content.
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