[Meta-analysis of Straw Return Effects on Salt Regulation and Crop Yield Improvement in Saline Soils of China]

Soil salinization severely limits the productivity of arable land， highlighting an urgent need for cost-effective amelioration technologies. Straw return to fields presents a dual opportunity for resource recycling and salinity regulation. However， its comprehensive effects on saline soil improvement and crop yield enhancement have yet to be quantitatively assessed. In this study， we conducted a Meta-analysis synthesizing data from 40 published studies across China's mainland， encompassing 325 records of soil electrical conductivity and 256 records of crop yield. We systematically evaluated the interactive effects of climatic factors （annual mean temperature， precipitation， and evaporation）， soil characteristics （initial salinization level and pH）， and agronomic practices （straw type， application rate， return method， straw length， and incorporation depth） on the efficacy of straw return in saline soils. Our results demonstrate that straw return significantly reduced soil electrical conductivity by 22.14% （P<0.05） and increased crop yield by 29.11% （P<0.05）. In warm and humid climatic zones （annual mean temperature>14℃， precipitation>400 mm， evaporation<1 500 mm） and in strongly saline-alkaline soils with weak alkalinity （pH 8-9）， soil salinity reductions reached 30.63%-54.02%. The optimal strategy for salt control involved the application of biochar-modified wheat straw at rates exceeding 20 t·hm^-2， with straw lengths of 10-15 cm and deep incorporation （20-40 cm）. In contrast， the greatest yield improvements were achieved using straw lengths of 10-15 cm with shallow incorporation （0-20 cm）； significant yield increases were observed for wheat and sunflower， while cotton did not respond significantly. In summary， straw return is an effective strategy for both ameliorating saline soils and enhancing crop productivity， although its efficacy is mediated by synergistic interactions among climatic， soil， and management factors. Site-specific optimization of straw return practices-taking into account regional climate， soil properties， and crop type-represents a crucial approach for promoting sustainable agricultural development in saline-affected regions.