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.