Soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometry is essential for maintaining fertility and ecosystem functioning, yet its spatial patterns and drivers in large-scale agricultural regions remain unclear. We collected 225 topsoil samples across the Songnen Plain, Northeast China, and used geostatistical methods to map the spatial distributions of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and their ratios (C:N, C:P, N:P). Feature importance and correlation analyses were employed to assess the relative influence of environmental factors. Results revealed significant spatial heterogeneity, with a consistent north-high, south-low pattern for all elements and ratios. Mean C:N, C:P, and N:P ratios were 11.6, 32.8, and 2.8, respectively. SOC was the dominant controlling factor (importance: 0.5–0.6), showing strong positive correlations with all ratios. Mean annual temperature exerted significant negative effects, while precipitation had limited influence, primarily on C:N. Soil type also mattered, with black soils exhibiting the highest C:N and C:P ratios (11.8 and 36.7). We conclude that soil C:N:P stoichiometry in the Songnen Plain is governed by hierarchical interactions of SOC, climate, and soil type. These findings provide a mechanistic framework for understanding regional nutrient patterns and support the development of spatially targeted management strategies for sustainable soil health.
Qin et al. (Thu,) studied this question.