Monday, November 2, 2009
Convention Center, Exhibit Hall BC, Second Floor
Most forage-livestock production systems possess hay-feeding areas where animals may congregate for extended periods. These areas may become overgrazed and compacted from trampling and have little ability to recover. The disturbed areas also may be focal points for weed invasion or nutrient loss. In 2008, a study was initiated at the Virginia Tech Shenandoah Valley AREC at Steeles Tavern, VA to evaluate the impact of concentrated hay feeding areas on pasture ecosystem functioning. In this study, we evaluated 24, 1 ha pastures within a rotationally stocked grazing system. One half (12 pastures) were stocked with 7 or 8 beef cows and fed hay from January to April. The other 12 were rotationally grazed during the growing season and had no hay feeding area. Within paired pastures, we measured forage yield, forage nutritive value and species composition, soil fertility indices, soil compaction and soil CO2 flux. In 2008, pastures with hay feeding areas had less forage in early spring (539 kg DM ha-1 ) compared with rotational pastures (750 kg DM ha-1). Later in the growing season, forage yield became similar between treatments. In spring, crude protein was also significantly higher in hay feeding sites (196 g kg-1 vs. 180 g kg-1) but this did not persist. Plant species composition exhibited no clear differences between pastures. Neither soil P nor pH differed significantly (P > 0.05) between hay feeding areas and rotational pastures. Soil penetration resistance (PR) measurements showed that pastures with hay feeding areas were more compacted than rotational pastures. The mean PR measurements were less than 2500 KPa though, which is considered the threshold where compaction adversely impacts plant growth. Our initial data suggests that concentrated hay-feeding areas had no long-lasting effects on the functioning of pasture ecosystems. Longer-term data will be needed to confirm these initial findings.