Sustainable agronomic practices on crop straw improve grain yield and soil quality in saline-alkali soil: A meta‑analysis of global literature with a China‑dominant dataset

Saline-alkali soil is an important potential land resource to compensate for the decreasing cultivated land. Improving grain yield and soil quality of saline-alkali soil is of great significance for ensuring the sustainable development of agriculture. Crop straw has already been demonstrated as a sustainable amendment to promote grain yield and soil quality. However, the effects of straw amendment in saline-alkali soil still lacks comprehensive assessment. Here, we conducted a meta-analysis using 105 publications to assess the effects of straw amendment and the potential driving factors in saline-alkali soil based on global literature with a strong China-dominant dataset. Overall, straw amendment significantly increased grain yield, soil organic matter (SOM) by 21.5%, 17.2%. While the soil bulk density (SBD), soil salt content (SSC), pH were decreased by 5.7%, 27.4%, 1.2%, respectively. Sub-group analysis showed that the effect sizes were more pronounced under lower mean annual temperature (MAT≤ 8). And in soil with higher degree of salinization (SSC>6 or pH>10) and lower SOM (≤ 8), the effects would be more significant for all the indicators. Optimizing agronomic practices enhanced the effects of straw, which higher nitrogen fertilizer (>180), appropriate straw using rates (≤ 7.5) and deep tillage would be more beneficial to grain yield and soil quality. Variation partitioning analysis (VPA) showed that the initial soil properties explained most of the variance on SSC (38%) and grain yield (58%). And agronomic practices explained most of the variance of SOM (22%). And then, the driving factors on the effects of straw amendment were quantified, which initial soil pH was one of the most important factors affecting the SSC, SOM and grain yield. Besides initial soil pH, the initial salt content, mean annual precipitation (MAP) affected more for SSC, MAT. And initial SOM affected more for SOM, straw using rates and initial soil salt content affected more for grain yield. Correlation analysis indicated that the effect sizes of each indicator showed different correlations with the climatic conditions, initial soil properties and agronomic practices. Those results would provide reference for the sustainable utilization of crop straw in saline-alkali soil.