Changes and controlling factors of cropland soil organic carbon in North China Plain over a 30-year period

Abstract

Try to detect the spatiotemporal dynamics and the controlling factors of soil organic carbon (SOC) in the North China Plain (NCP) over the last 30 years: 1980s-2010s. We investigated the SOC evolution by compiling data from 32 published papers during the last 30 years. Then we examined the spatial pattern and controlling factors by analysing a two-period sampling observations (1980s and 2010s) and multiple explanatory variables in four typical counties. Over the last 30 years, the agronomy environment and management practice have been dramatically improved, which have largely increased the crop yield and subsequently enhanced the C input into the soil, made NCP the most effective region for C sequestration in China, ranging from 5.55 ± 1.28 g kg−1 in the 1980s to 8.71 ± 1.22 g kg−1 in the 2010s, with an average rate of 0.11 g kg−1 year−1. The SOC change (SOCC) exhibited spatial heterogeneity due to imbalanced agricultural management (i.e., rotation and irrigation) and environmental obstacles (i.e., salinity and water deficit). The mean SOCC rate in Fengqiu and Yucheng (> +0.15 g kg−1 year−1, with rotation of winter wheat and summer maize, less water deficit and salinity stress) were significantly (P < 0.05) higher than that in Nanpi (< +0.10 g kg−1 year−1, with water deficit) and Kenli (< +0.10 g kg−1 year−1, cotton only, salinity stress). SOC may continue to increase in the NCP through sustainable and efficient agricultural management, especially in low-yield region. Soils in the NCP will still act as a C sink well in the future.