Impacts of straw return methods on crop yield, soil organic matter, and salinity in saline-alkali land in North China

Abstract

Context

Straw return is a prevalent strategy for the amelioration of saline-alkali land, and it primarily comprises three techniques: straw mulching (SM), straw burial (SB), and straw incorporation (SI).

Research question

However, few studies have systematically compared the effects of these straw incorporation techniques on the improvement of saline-alkaline soils. It is necessary to assess the advantages and limitations of various straw incorporation strategies to achieve sustainable agricultural development in saline-alkaline soils.

Methods

This study synthesized data from 86 published articles to obtain 976 paired observations and evaluated the impacts of three straw return methods on crop yield, soil organic matter, and soil salinity under various environmental conditions and agronomic practices.

Results

Overall, all the straw return measures significantly increased crop yield (mean effect size: 18 %), enhanced soil organic matter (19 %), and alleviated soil salinization (-15 %). However, the ameliorative effects varied with straw return methods; specifically, SM (77 %) outperformed the other two methods (SB 21 %, SI 17 %) in increasing crop yield, while SI was more effective in enhancing soil organic matter. The ameliorative effects varied with regions; specifically, all the three methods significantly increased crop yield in coastal regions, but only SB yielded significant improvement in North China. With mean annual precipitation of < 200 mm or 200–400 mm, SB and SI significantly increased crop yield and soil organic matter (SOM). Under severe soil salinity (pH > 8.5, soil salt content > 4 g/kg) conditions, SI was superior in increasing crop yield and soil organic matter. In clay loam soil, SM significantly increased SOM and reduces salt content, but had no significant impact on crop yield. Additionally, we identified the driving factors of crop yield, soil organic matter, and soil salinity, as well as optimal agronomic management measures under different straw return methods.

Conclusions

Adopting different straw return methods under various environmental conditions and choosing suitable agronomic management practices based on these methods can significantly enhance the amelioration effect on saline-alkali soils.

Significance

This study provides a scientific basis for selecting appropriate straw return methods in various saline-alkali regions worldwide, enhancing soil improvement outcomes and promoting the sustainable use of saline-alkali land.