The Spatial Characteristics of Soil Organic Carbon Sequestration and N₂O Emission with Long-Term Manure Fertilization Scenarios from Dry Land in North China Plain

To provide theoretical guidance for mitigating global warming, the comprehensive effects of manure amendment on soil organic carbon sequestration and greenhouse gas emissions were studied.

Based on the long-term experiment, the validated process-based model-SPACSYS, combined with regional database and ArcGIS, was used to clarify the spatial characteristics of average annual soil organic carbon sequestration rate (SOC_SR), average annual soil N₂O emission and average annual net global warming potential (NGWP) under three long-term fertilization scenarios (equal nitrogen fertilization), namely, chemical fertilizers only (NPK), 50% of chemical fertilizers combined with 50% of manure (NPKM(5:5)) and 30% of chemical fertilizers combined with 70% of manure (NPKM(3:7)), from dry land in the North China Plain from 2010 to 2050.

The SOC_SR from dry land in the North China Plain was higher in the east and lower in the west, and the higher regions mainly included Jiangsu Province and Shandong Province. Correlation analysis showed that there was a significant negative correlation between SOC_SR and initial soil organic carbon content. Stepwise linear regression analysis further indicated that initial soil organic carbon content, mean annual temperature and soil pH were three important factors affecting SOC_SR, which accounted for 24% of the variation of SOC_SR. The average annual soil N₂O emission was higher in the central part of the North China Plain, lower in the north and south, and the higher regions included parts of Shandong Province and Jiangsu Province. Correlation analysis showed that there was a significant positive correlation between average annual soil N₂O emission and initial soil organic carbon content. In general, compared with NPK, NPKM(5:5) and NPKM(3:7) both increased SOC_SR and decreased average annual soil N₂O emission from dry land in the North China Plain, of which SOC_SR (233 and 236 kg C·hm^-2·a^-1) increased by 79% and 82%, respectively, the average annual soil N₂O emission (15.8 and 14.4 kg N·hm^-2·a^-1) decreased by 21% and 28%, respectively. As a result, NGWP (6.6 and 5.9 t CO₂-eq·hm^-2·a^-1) decreased by 26% and 34%, respectively.

Compared with the application of chemical fertilizers, the application of chemical fertilizers combined with manure was beneficial to SOC sequestration, soil N₂O emission reduction and mitigation of glowing warming from dry land in the North China Plain over the long-term.