Soil Organic Carbon Improves Crop Yield and Yield Resilience

Area of Science:

• Agricultural Science
• Soil Science
• Climate Science

Background:

• Soil organic carbon (SOC) is recognized for improving soil water-holding capacity and crop yield resilience.
• Its role in mediating crop responses to hydroclimatic stress, especially drought, requires further investigation.

Purpose of the Study:

• To analyze how soil organic carbon (SOC) influences the relationship between US rainfed crop yields and hydroclimatic conditions.
• To determine the extent to which SOC enhances crop yield resilience under varying water supply and demand.

Main Methods:

• Analysis of US rainfed crop yields from 1981-2020 across 67,000 county-years for three major crops.
• Examination of hydroclimatic conditions defined by soil water supply and atmospheric water demand.
• Statistical assessment of SOC's mediating effects on yield variability and gains.

Main Results:

• Higher SOC is consistently linked to increased crop yields and reduced interannual yield variability, indicating enhanced resilience.
• The most significant yield increases attributed to SOC were observed under moderate water supply conditions, not during drought.
• SOC's benefits under drought are constrained by limited water inputs, highlighting that water storage capacity alone is insufficient.

Conclusions:

• Soil organic carbon (SOC) enhances crop yield resilience to hydroclimatic stress but cannot fully compensate for extreme drought.
• The positive impact of SOC on crop production is most pronounced under moderate environmental conditions due to their higher frequency.
• Effective delivery of SOC's water-related services to crops necessitates adequate water availability.