Purpose To identify the spatial variability characteristics of soil fertility in the main production areas of winter-early vegetables in Yuanmou County, Yunnan Province, providing a scientific basis for soil fertility management in the area.
Methods A total of 28 sampling points in the main open-field vegetable production areas of Yuanmou County were selected. Soil samples were collected and analyzed for 11 soil fertility indexes, including pH, electrical conductivity, moisture content, bulk density, and the content of organic matter, total salt content, available phosphorus, available potassium, nitrate nitrogen, exchangeable calcium, and exchangeable magnesium. Spatial variability characteristics analysis was conducted by ArcGIS. Additionally, membership function curves were selected and determined, comprehensive scores of soil fertility were calculated based on the weight values and membership values of each soil fertility index. Principal component analysis and cluster analysis were conducted to comprehensively evaluate the soil fertility of the vegetable fields.
Results The average pH value of the typical open-field vegetable soils in Yuanmou County was 7.54, indicating weakly alkaline soils. The organic matter and available potassium contents were high, while the available phosphorus content was at an upper-moderate level. The spatial distribution characteristics of soil organic matter and exchangeable magnesium were very similar, and the spatial distribution of soil electrical conductivity, total salt content, and available phosphorus were consistent. Single soil fertility index analysis indicated that the radar chart areas of the membership values for Laocheng Town and Huangguayuan Town were larger, and the variability of pH, available potassium, electrical conductivity, and total salt content among the four townships were smaller , but the variability of organic matter, exchangeable magnesium, and available phosphorus were larger. Principal component analysis revealed that the first three principal components accounted for 70.670% of the total information. Organic matter had the highest weight coefficient (0.112 8), followed by exchangeable magnesium (0.112 5) and available phosphorus (0.112 3). The comprehensive soil fertility scores of Yuanmou’s vegetable fields ranged from 0.247 to 0.903, with 60.7% of the sampling points below the average score, mainly concentrated in Wumao Town and Yuanma Town. Cluster analysis showed that the sampling points in the county could be divided into two categories: good fertility type (39.29%) and moderate fertility type (60.71%).
Conclusion The open-field vegetable soils in most areas of Yuanmou County have good fertility levels. Organic matter, exchangeable magnesium, and available phosphorus contribute significantly to soil fertility and play important roles in the fertility of the vegetable fields in the county. However, the soil fertility in some areas needs urgent improvement.
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