Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well unders...Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.展开更多
It was considered that sheep husbandry was undeveloped according to the folk custom,tax items,the conditions on human resources and environment,and mutton supplies for royal or imperial government before the Tang Dyna...It was considered that sheep husbandry was undeveloped according to the folk custom,tax items,the conditions on human resources and environment,and mutton supplies for royal or imperial government before the Tang Dynasty,although sheep or goats were the ancient animals which were trained and raised 7000 years ago.In the farming region controlled by Central Plains Dynasties the common people kept a few sheep.The developed sheep husbandry mainly relied on the war plundering,sheep of national minorities who migrated from prairies,tributes from the military officer and the minorities who submitted to Central Plains Dynasty,and the exploitation of the Hetao area during the Han-Tang Dynasty.Most of sheep were kept in official grazing land and private pastureland of bureaucrats and nobles at that time.展开更多
基金Supported by the USDA-NRI,USA(No.NRI-2007-03307)the USDA Southern Region SARE Program,USA(No.2012-02978)+2 种基金the China Scholarship Council(No.[2006]3085)the National Natural Science Foundation of China(No.41201259)the Natural Science Foundation of Shaanxi Province,China(No.2013JQ5001)
文摘Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.
文摘It was considered that sheep husbandry was undeveloped according to the folk custom,tax items,the conditions on human resources and environment,and mutton supplies for royal or imperial government before the Tang Dynasty,although sheep or goats were the ancient animals which were trained and raised 7000 years ago.In the farming region controlled by Central Plains Dynasties the common people kept a few sheep.The developed sheep husbandry mainly relied on the war plundering,sheep of national minorities who migrated from prairies,tributes from the military officer and the minorities who submitted to Central Plains Dynasty,and the exploitation of the Hetao area during the Han-Tang Dynasty.Most of sheep were kept in official grazing land and private pastureland of bureaucrats and nobles at that time.
