|Wullschleger, S - OAK RIDGE NATL LAB|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2001
Publication Date: N/A
Technical Abstract: Rangeland grazing management strategies affect soil properties and the distribution and cycling of nutrients within the plant-soil system, but these effects are not well understood. We studied the effects of 12 years of five livestock grazing management strategies on (C) and nitrogen (N) contents of a semi-arid, mixed-grass prairie in Wyoming. Grazing treatments were: no grazing, continuous, season-long light grazing, continuous season-long heavy grazing, and two rotation management systems at a heavy stocking rate. The type of grazing management strategy used had no effect on plant or soil C and N, but stocking rate changed plant community composition and altered the distribution of C and N in the plant-soil system. Eliminating livestock grazing caused an increased production of undesirable weedy plants and a large buildup of dead plant material on the soil surface. Grazing at a heavy stocking rate also produced undesireable changes in plant community composition. Light grazing resulted in a stable, productive plant community of desireable species. The C and N contents of the surface 15 cm (6 inches) of the soil were significantly lower in non-grazed pastures than in all grazed pastures. Grazing appears to have increased surface soil C and N content in part by stimulating litter decompostion and recycling, which allows earlier spring green-up because of better light penetration and a warmer soil surface.