Effects of long-term straw return on grain yield stability in China: A meta-analysis

Context or problem

Amid global climate change and extreme weather, ensuring food security and stable grain yields is critical. Straw return is recognized as a crucial practice for enhancing soil fertility and carbon sequestration, boosting grain yields. Although straw return has been widely studied, its long-term effects on yield stability are still not well understood. In contrast to previous meta-analyses that have mainly focused on mean yield, this study addresses yield stability as a critical yet underexplored factor in sustainable agriculture.

Objective or research question

This study aims to quantify the effects of long-term straw return on mean grain yield and yield stability, while assessing its influence on soil organic carbon (SOC) content and temporal SOC stability. We further examine how straw return practices (methods and quantity), fertilization, crop types, and the SOC content and its temporal stability affect the yield stability.

Methods

We conducted a meta-analysis of 193 multi-year observations (≥4 years) from 68 studies (1562 comparisons) across China. This analysis evaluated the effects of long-term straw return on mean yield, yield stability, SOC, temporal SOC stability, and soil fertility. We employed Random Forest modeling and linear fitting to evaluate the relationships between straw return practices, fertilization, crop types, and resulting outcomes.

Results

Long-term straw return simultaneously enhanced both the mean grain yield (+6.78 %) and yield stability (+4.38 %), with the most pronounced benefits observed when straw was crushed and incorporated through deep plowing or within the plow layer. Excessive straw return reduced yield and stability, while optimal N fertilizer use improved stability. Long-term straw return increased soil organic carbon (SOC, +12.2 %) but decreased temporal SOC stability (-43.5 %). It also increased soil total nitrogen (N) and phosphorus (P) content. Enhanced SOC and total N content significantly increased both mean yield and yield stability under straw return.

Conclusions

Long-term straw return effectively enhances the yield stability of crops and SOC sequestration in China. The enhancement of SOC and total N content is key for promoting both the mean yield and yield stability under straw return conditions. Overall, long-term straw return enhances C, sustains soil fertility, and thereby achieves increased and stable grain yield, ultimately ensuring food security.

Implications or significance

These findings provide evidence-based strategies for achieving stable yields under climate change. The identified optimal practices (straw crushing, incorporation methods, N fertilization range) offer actionable solutions for policymakers and farmers to enhance food security while promoting carbon sequestration in croplands.