Tuesday, November 6, 2007
222-16

Impact of Sheep Bedding on Soil Nutrient Status in the Centennial Mountains of Montana and Idaho.

April B. Leytem, USDA-ARS, 3793N 3600E, Kimberly, ID 83341 and S.S. Seefeldt, USSES, USDA-ARS, Dubois, ID 83543.

Sheep and lamb production is an important industry in the state of Idaho, with sheep grazing in the mountains during summer months a common practice.  Sheep are concentrated in bedding areas at night to guard them from theft and predation which leads to concentrated grazing and manure and urine accumulation in the bedding areas. The effects of heavy grazing along with manure and urine accumulation have the potential to alter soil nutrient status over time which can ultimately alter the vegetative communities in these bedding areas.  To address the effects of sheep bedding areas on soil nutrient status we monitored the nutrient status of soils from within and outside of sixteen bedding areas in the Centennial Mountains of Montana and Idaho, with a general survey performed in 2004 followed by more intense monitoring of six sites from 2005 to 2006.  The sixteen sites evaluated in 2004, showed significant differences in total N, C and organic C, with the control sites having greater concentrations.  The Olsen P, WSP, and ammonium were also significantly different on the sixteen sites, with the bedding areas having greater concentrations than control areas. When six sites were monitored over time there was no significant effect of bedding on soluble P concentrations over time or between bedding and control areas, while there was a significant effect of time on soluble N concentrations but no significant differences between bedding and control areas. In general soluble N increased following bedding and then decreased again during the subsequent spring.  Although these results are preliminary, it appears as if sheep bedding can alter the nutrient content of soils both increasing some measures of soil nutrients, while decreasing others, which ultimately can affect the productivity and plant species diversity in these areas.