2021 journal article
Soil nutrient distribution on cattle farms in three physiographic regions of North Carolina
AGRONOMY JOURNAL, 113(1), 590–609.
Beef cattle production systems are sometimes considered a source of nutrient enrichment due to alteration of botanical composition and excretion of nutrients in isolated zones of pastures. However, research on environmental effects from livestock grazing in the eastern United States has been scant. We conducted an intensive soil sampling campaign on six private farms in three physiographic regions of North Carolina to determine the impacts of landscape features, pasture management, and animal behavior on a suite of soil nutrients. Total and particulate organic C and soil-test biological activity (STBA) increased with increasing elevation due to edaphic and climate factors. Within farms, fields with different management illustrated that: (a) swine and poultry manure application can favorably enrich soil with infrequent application, but lead to excessive soil-test P and K with repeated application; (b) positive impacts on total and particulate organic C and STBA occur with grazed perennial forages compared with annual forages and previous cropping; and (c) enrichment of total and particulate organic C and STBA occurs with winter hay feeding, but excessive nutrient accumulation can occur if fed in the same location repeatedly. Aggregated enrichment of soil organic C, STBA, and soil-test P and K occurred on 30% of fields near drinking water tanks, shade sources, gates, and hay feeding stations. Improved grazing management with rotational stocking and more year-round grazing helped to minimize occurrence and magnitude of nutrient enrichment zones. We conclude that improved grazing management systems can have positive impacts on the environment, and likely on farm livelihoods.