Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2008
Publication Date: 12/17/2008
Citation: Owens, L.B., Shipitalo, M.J. 2009. Runoff quality evaluations of continuous and rotational over-wintering systems for beef cows. Agriculture, Ecosystems and Environment. 129(4):482-490. Interpretive Summary: Winter weather increases the challenges of livestock management, especially if the livestock are not confined. For out-wintering of grazing animals, winter feeding requires different management than at other times of the year. Much feed, usually hay, needs to be brought to the livestock and at a time the weather causes grazing areas to be much more vulnerable to loss of vegetation, compaction, increase surface runoff, and increased soil loss. Although research on the environmental aspects of grazing has addressed a number of concerns, there is very little investigation of the environmental impacts of different systems for out-wintering livestock. Grazing research with beef cattle has been conducted at the North Appalachian Experimental Watershed near Coshocton, Ohio for several years. During these studies, cattle have been kept in one area for the winter and had hay brought to them. In another system the cattle were rotated through fields to eat fall regrowth and then rotated through the same fields again to eat the hay that had been made in them during the summer. Vegetative cover in the continuous wintering area frequently decreased to less than 50% by late winter/early spring. Annual surface runoff was 3 times greater from the continuous wintering than from the rotational wintering, and soil loss was 11 times greater from the continuous wintering than the rotational wintering. April had the highest average monthly runoff and erosion. Cattle were on a given area longer with the continuous wintering than the rotational wintering. So, even though the rotational wintering system was more environmentally sustainable than the continuous wintering system, more land area per cow was necessary. This information is relevant to other grazing land scientists as well as producers and land managers.
Technical Abstract: Over-wintering cattle out of doors can be detrimental to the areas that the cattle occupy and cause increased runoff, sediment loss, and nutrient transport. As management practices vary, the impacts on the occupation areas vary. Two systems of over-wintering cattle were evaluated for their environmental impacts over a 12-yr period. In a high fertility system, beef cows were rotated weekly during the summer. They were then rotated through fall regrowth on hayed areas and rotationally fed hay in those areas. In a medium fertility system, cattle were rotated weekly during the summer and then continuously fed hay in one winter area. Vegetative cover in the continuous wintering area frequently decreased to less than 50% by late winter/early spring. Monthly runoff averages were greater from the continuous wintering system than the rotational wintering system in 9 out of 12 months (annual runoff of 120.4 and 37.5 mm, respectively), with the greatest difference being in April. Similarly, sediment loss was greater from the continuous system (2.68 and 0.24 Mg ha-1, respectively), with the greatest losses occurring in April. Surface runoff losses of N were greater during the dormant season than the growing season for both systems. Average annual total N transported for the 12-yr period during the dormant seasons was 13.2 and 6.7 kg ha-1 for the continuous and rotational wintering systems, respectively; for the growing seasons, it was 4.6 and 1.3 kg ha-1, respectively. Runoff N losses were considerably less than leaching losses. Runoff, sediment, and N losses were less with a rotational wintering system than with a continuous occupancy wintering system. But for the two systems studied, the cattle occupancy rate was also much greater in the continuous wintering system compared with the rotational wintering system (1497 and 1860 cow days ha-1 compared with 528 and 576 cow days ha-1). This shows that a rotational wintering system is more sustainable than a continuous wintering system, but more land area per cow would be necessary.