Amping up soil carbon: soil carbon stocks in California rangelands under adaptive multi-paddock and conventional grazing management ⋆ Savory Institute

Science Article

Amping up soil carbon: soil carbon stocks in California rangelands under adaptive multi-paddock and conventional grazing management

Stanley, P., Roche, L., & Bowles, T. (2025). Amping up soil carbon: soil carbon stocks in California rangelands under adaptive multi-paddock and conventional grazing management. International Journal of Agricultural Sustainability, 23(1). https://doi.org/10.1080/14735903.2025.2461826

Key Takeaways

Holistic Planned Grazing (referred to as AMP grazing in this paper) led to significantly higher soil carbon stocks than conventional continuous grazing across both northern and central California sites.
Soil carbon gains were especially pronounced in deeper layers (30–50 cm), suggesting long-term stabilization rather than surface-only accumulation.
AMP-grazed pastures had 13–29% higher soil carbon stocks than conventionally grazed counterparts, depending on location.
These carbon gains persisted after controlling for climate, soil type, and elevation, strengthening the case for management as the key driver.
AMP systems featured higher forage utilization and rest periods, aligning with regenerative practices aimed at optimizing plant recovery and soil cover.
No significant trade-offs were found in bulk density or soil compaction, countering concerns that increased grazing intensity would harm soil structure.
Carbon stock improvements occurred despite only modest differences in overall precipitation, highlighting that management—not just rainfall—drives soil carbon outcomes.
Study used direct measurement (soil cores) across 64 ranches, making it one of the most robust comparative studies of AMP vs. conventional grazing in California.
AMP grazing supports climate mitigation goals while maintaining productivity, offering co-benefits for both land health and emissions reduction.

Summary

Adaptive multi-paddock (AMP) grazing is gaining attention for its potential to increase soil organic carbon (SOC), yet its efficacy on arid and semi-arid rangelands remains debated. Given the adaptive nature of AMP, on-ranch studies are essential for measuring its applied outcomes. To assess AMP’s impact on Mediterranean California rangelands, we collected 1,440 soil samples from four paired AMP and conventional (CONV) grazing sites across northern California. Three AMP ranches had significantly greater SOC stocks in surface soils (17% greater SOC at 0–10 cm), and two had greater SOC stocks to 100 cm (32% greater), compared to CONV ranches. The largest SOC differences occurred in the mineral-associated organic matter fraction, suggesting longer-term SOC storage. While plant community composition did not differ significantly, AMP ranches, on average, had slightly less bare ground, greater live plant cover, and two sites had 82% greater perennial grass cover. These factors may have contributed to SOC differences. Further research is needed to understand site-specific constraints, underlying mechanisms, and SOC changes over time under AMP grazing.