Soil nutrient distribution on cattle farms in three physiographic regions of North Carolina

Authors: Franzluebbers, Alan; POORE, MATTHEW - North Carolina State University; FREEMAN, SHARON - North Carolina State University; ROGERS, JOHNNY - North Carolina State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2020
Publication Date: 1/18/2021
Citation: Franzluebbers, A.J., Poore, M.H., Freeman, S.R., Rogers, J.R. 2021. Soil nutrient distribution on cattle farms in three physiographic regions of North Carolina. Agronomy Journal. 113:590-609.

Interpretive Summary: Grazed pastures are sometimes considered a source of nutrient enrichment that can lead to contamination of water receiving bodies. However, limited information is available on the geospatial nutrient distribution on farms having grazing cattle. A scientist from USDA-Agricultural Research Service in Raleigh NC collaborated with a team of livestock scientists from North Carolina State University to evaluate geospatial distribution of organic and inorganic nutrients in surface soil on six private farms across three physiographic regions of North Carolina, i.e. the Coastal Plain, Piedmont, and Blue Ridge regions. Soil organic carbon and soil-test biological activity levels were generally greater on farms at higher elevation than lower elevation. Within a farm, fields with perennial forages had greater soil organic carbon and soil-test biological activity than fields with annual forages or a history of recent cropping. Evidence was found of enrichment of soil-test phosphorus and potassium in zones near shade, water, and hay-feeding stations. However, the occurrence was on less than half of the fields and the intensity of enrichment was generally lower than in another study where hay-feeding stations were in the same place year after year. Progressive livestock management with moderate stocking rate, rotational stocking, fall stockpiling for winter grazing, and limited hay feeding were identified as possible reasons for minor geospatial concentration of nutrients on these farms.

Technical Abstract: 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. Quantification of environmental effects from livestock grazing in the eastern US has been minimally investigated. 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 organic and inorganic 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: (1) the effects of repeated swine and poultry manure application on soil-test P and K that can become excessive, (2) the positive impacts of perennial forages compared with annual forages and previous cropping on total and particulate organic C and STBA, and (3) the positive effects of hay feeding on total and particulate organic C and STBA, but that can lead to excessive nutrient accumulation if fed in the same location repeatedly over time. Aggregated enrichment of soil organic C and soil-test P and K occurred occasionally near drinking water tanks, shade sources, gates, and hay feeding stations. However, because these private farms adopted improved grazing management with rotational stocking and more year-round grazing, nutrient enrichment zones were minimized in occurrence and magnitude. We conclude that improved grazing management systems can have positive impacts on the environment, and likely on farm livelihoods.