Does continuous straw returning keep China farmland soil organic carbon continued increase? A meta-analysis

Area of Science:

• Agricultural Science
• Soil Science
• Environmental Science

Background:

• Straw returning is a key practice for soil carbon sequestration and improving soil organic carbon (SOC).
• Regional variations in straw utilization and its impact on SOC in China are not well understood.
• Understanding factors influencing straw returning effectiveness is crucial for sustainable agriculture.

Purpose of the Study:

• To analyze the effects of straw returning on soil organic carbon (SOC) across China.
• To identify environmental and management factors influencing SOC changes due to straw returning.
• To provide data-driven recommendations for optimizing straw returning practices.

Main Methods:

• Meta-analysis of 446 datasets from 95 studies in Chinese fields.
• Statistical analysis of environmental factors (precipitation, temperature) and soil properties (texture, initial SOC).
• Evaluation of different agricultural systems (continuous cropping, crop rotation) and management practices (tillage, straw amount, nitrogen fertilization).

Main Results:

• Straw returning significantly increased SOC by an average of 13.97%.
• Positive effects were more pronounced in areas with mean annual precipitation > 500 mm, mean annual temperature > 10°C, loam/sandy soils, and initial SOC < 10 g kg⁻¹.
• Optimal straw returning duration is 6-9 years; effects diminished or reversed after 10 years. Maize-wheat rotations and specific fertilization rates showed enhanced SOC benefits.

Conclusions:

• Straw returning is an effective strategy for increasing soil organic carbon in China.
• Environmental conditions and specific management practices significantly modulate the effectiveness of straw returning.
• Optimizing straw returning duration, crop rotation, and fertilization is essential for maximizing soil carbon sequestration benefits.