Could High Density Rotational Stocking Promote Higher Productivity, Resiliency and Carbon Sequestration Potential?.

Global warming poses a threat to the stability of grassland-based agriculture and the ability of these systems to sequester atmospheric CO₂.  Alternative management strategies for humid grasslands must be tested to help livestock producers cope with these challenges.  The overarching goal of the proposed study seeks to determine whether increased intensification of grazing management can produce more productive, climate resistant grasslands that have a greater capacity to sequester carbon.  At three locations in Virginia, three grazing systems involving high desnity rotational stocking (HDRS), rotational and continuous stocking have been compared since 2013.   Plant-related variables have been evaluated extensively to date, and we have interesting preliminary data related to soil microbial processes.  Herbage mass was significantly greater under HDRS stocking compared with the other grazing systems.  Greater herbage mass likely resulted from a combination of two factors: 1) higher net primary production especially during late summer, and 2) cattle consuming less herbage mass under mob stocking because much of the forage base was trampled.  Herbage nutritive value did not differ greatly among the systems, except for one location that experienced drought.  There protein content also was elevated more under HDRS that fall following late season rains.  This preliminary data suggests grasslands with HDRS may be more resilient, and recover faster from drought.  At one location, soils under HDRS showed a 33% increase in mineralizable C compared with continuous stocking.  More mineralizable C should favor slower cycling pools of soil C will that ultimately could promote carbon sequestration.  Taken together, our preliminary findings suggest that HDRS promotes resilience in response to drought and leads to greater carbon sequestration potential.