Strategies that simultaneously sequester atmospheric carbon and improve food and fiber production are important if we hope to slow climate change and feed a growing population. One strategy that can improve production and might also sequester carbon is rotational grazing (RG). This practice intensively grazes small paddocks for short periods before moving the herd to the next paddock, allowing the first plot time to recover. Compared to continuous or "free" grazing, RG has been shown to increase forage production under some conditions. This indicates that RG may promote compensatory growth of some grass species. It also indicates that RG might increase soil inputs, which could increase soil organic carbon stocks (SOC). Slightly over one decade ago, farmers received grants to help them implement rotational grazing systems on their farms in Virginia. Within a few years of this transition, we took soil samples on their farms to develop baseline carbon stock estimates. GPS and buried ball markers will allow us to take new samples within a foot of the original sample points, constraining the amount of spatial variability and maximizing our ability to detect changes over time.
Results/Conclusions
Preliminary results from 3 farms showed that RG systems' carbon stocks increased by 22.3% when compared "across the fence" to extensive grazing systems. This was determined to be significant on each farm with significant p-values of at least alpha < .05, but analysis in place over time can improve our certainty that management has influenced these changes. Indeed, by resampling now, ten years later, we expect our knowledge of the system dynamics will be much more definitive. This resampling effort is an important component of our efforts to better understand the mechanisms driving management-induced changes in soil carbon dynamics in mesic grassland systems.
