Large soil organic carbon increase due to improved agronomic management in the North China Plain from 1980s to 2010s

Abstract

Agricultural soils are widely recognized to be capable of carbon sequestration that contributes to mitigating CO emissions. To better understand soil organic carbon (SOC) stock dynamics and its driving and controlling factors corresponding with a period of rapid agronomic evolution from the 1980s to the 2010s in the North China Plain (NCP), we collected data from two region-wide soil sampling campaigns (in the 1980s and 2010s) and conducted an analysis of the controlling factors using the random forest model. Between the 1980s and 2010s, environmental (i.e. soil salinity/fertility) and societal (i.e. policy/techniques) factors both contributed to adoption of new management practices (i.e. chemical fertilizer application/mechanization). Results of our work indicate that SOC stocks in the NCP croplands increased significantly, which also closely related to soil total nitrogen changes. Samples collected near the surface (0-20 cm) and deeper (20-40 cm) both increased by an average of 9.4 and 5.1 Mg C ha , respectively, which are equivalent to increases of 73% and 56% compared with initial SOC stocks in the 1980s. The annual carbon sequestration amount in surface soils reached 10.9 Tg C year , which contributed an estimated 43% of total carbon sequestration in all of China's cropland on just 27% of its area. Successful desalinization and the subsequent increases in carbon (C) inputs, induced by agricultural projects and policies intended to support crop production (i.e. reconstruction of low yield farmland, and agricultural subsidies), combined with improved cultivation practices (i.e. fertilization and straw return) since the early 1980s were the main drivers for the SOC stock increase. This study suggests that rehabilitation of NCP soils to reduce salinity and increase crop yields have also served as a pathway for substantial soil C sequestration.

Depth‐dependent soil organic carbon dynamics of croplands across the Chengdu Plain of China from the 1980s to the 2010s

“…This suggests that the overall trend of subsoil SOC decreases has existed since the 1980s. Similarly, although some studies found overall trends of SOC increase in the 20–40 cm soil layer in other agricultural districts of China, their results also indicated that the SOC content of the 20–40 cm soil layer decreased in some subareas or soil types (Han et al, 2017; Yan et al, 2011). Compared with previous studies, we further found that the largest SOC decrease occurred in the 40–60 cm soil layer.…”

Growth and Distribution of Maize Roots in Response to Nitrogen Accumulation in Soil Profiles after Long-Term Fertilization Management on a Calcareous Soil

“…The North China Plain (NCP) plays an indispensable role in China's food provision, accounting for 32% of national grain production in 2015. Soils in the NCP are historically known to be low in fertility [18], which is a major challenge for crop production in this region. The low SOC (soil organic carbon) content is mainly due to the burning of crop straw after harvest and the insufficient application of organic manure.…”

Emergy-Based Sustainability Analysis of an Ecologically Integrated Model with Maize Planting for Silage and Pig-Raising in the North China Plain

“…The emergy of topsoil loss was calculated using soil organic carbon (SOC) concentration [29]. Thus, the factor of topsoil loss from the E L was canceled out as the SOC concentration of the entire North China Plain increased over the past 30 years under conventional tillage methods [30]. Three years of local SOC data from the Yucheng Comprehensive Experiment Station also verified this trend (Supplementary Material D).…”