Synergistic improvement of carbon sequestration and crop yield by organic material addition in saline soil: A global meta-analysis

The improvement and utilization of saline soil is an important guarantee for cultivating healthy soil, ensuring global food security, and mitigating the negative impacts of climate change. Organic material addition plays a crucial role in soil improvement and remediation, soil carbon sequestration, and improving soil fertilizer and productivity. In order to explore the comprehensive impact of organic material addition on properties of saline soil (including the physical and chemical properties, nutrient fixation, crop yield, and carbon sink capacity), we conducted a global meta-analysis using data from 141 articles. We found that, soil salinization significantly reduced plant biomass (50.1 %), soil organic carbon (20.6 %), and microbial biomass carbon (36.5 %). Meanwhile, it also reduced CO2 flux (25.8 %) and CH4 flux (90.2 %) significantly. Adding organic materials to saline soil significantly increased crop yield (30.4 %), plant biomass (30.1 %), soil organic carbon (62.2 %), and microbial biomass carbon (78.2 %), but also increased CO2 flux (221.9 %) and CH4 flux (29.7 %). Considering the balance of both carbon sequestration and carbon emissions, organic material addition significantly increased the net carbon sequestration by about 5890.7 kg CO2-eq·hm−2·100 d−1 on average. Besides, the organic material addition reduced soil salinity, exchangeable sodium, and pH, and increased >0.25 mm aggregates and soil fertility. Our findings suggest that organic material addition can improve both carbon sequestration in saline soil and crop yield. Considering the huge area of saline soil around the world, this understanding is essential to reduce the saline obstacle, improve the soil carbon sink capacity, ensure food security, and increase farmland reserves.