Grazing Impacts on Litter and Soil Organic Matter in Mixed Prairie and Fescue Grassland Ecosystems of Alberta

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Allen Press and Society for Range Management are collaborating with JSTOR to digitize, preserve and extend access to Journal of Range Management. AbstractImpacts of long-term cattle grazing on litter and soil organic matter were assessed in mixed prairie, parkland fescue, and foothills fescue grasslands of Alberta, Canada. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Litter and soil organic matter were sampled in 0.1-nM2 quadrats and removed as live vegetation, standing litter, fallen litter, and soil organic matter. Litter and organic matter samples were air dried and sorted by size using sieves and an automatic sieve shaker. Organic carbon content was determined by thermal oxidation. Ground cover was determined using point frames, and heights of standing litter and fallen litter were measured.Heavy intensity and/or early season grazing had greater negative impacts on litter and soil organic matter than did light intensity and/or late season grazing. Under the former regimes there were significant reductions in heights of standing and fallen litter, decreases in live vegetative cover and organic matter mass, and increases in bare ground. More large particle-sized organic matter, particularly standing litter, occurred in controls than in grazed treatments since it would not be removed or trampled by grazing animals. More medium and small particle-sized organic matter occurred in grazed treatments than in ungrazed controls since vegetation likely decomposed more rapidly when it was trampled and broken down as animals grazed.

Management of Canadian prairie region grazed grasslands: Soil C sequestration, livestock productivity and profitability

“…Less productive and less palatable vegetative species dominate, and livestock carrying capacity is reduced. Traditional season-long (continuous) grazing regimes on the Canadian Prairies and heavier grazing intensities also increase soil compaction and Naeth et al 1991). There is a lack of suitable information, stratified by grassland system (i.e., soil, climate and management combination) to accurately gauge historical losses of SOC stocks from Prairie grazed grasslands.…”

“…More accurate estimates of C sequestration through improved grazing by region could be obtained by including a weighting factor for the fraction of soil textural class in the coefficients of input to soil C (Smith et al 2001). From a hydrological perspective, maintenance of litter carryover through management of grazing intensities (Naeth et al 1991) may be equally as important as soil textural influences on soil water-holding capacity.…”

“…Native rangeland plants have co-evolved with rangeland animals, and a growing body of literature supports the contention that under light grazing pressure (and fire) climax vegetation communities are maintained and the productivity of the native range is maximized. The produc- tivity of these ecosystems may rely on the stimulation of C and N cycling by enhanced incorporation and decomposition of litter by grazing (Schuman et al 1999;Naeth et al 1991). Dormaar and Smoliak (1985) found that even after 55 yr of revegetation, abandoned farmland in southern Alberta had still not reached the soil organic C levels of adjacent native rangeland.…”

Grazing Management Effects on Sediment and Phosphorus in Surface Runoff

“…Damage caused by treading (Elliott et al 2002), decreased soil organic matter (Naeth et al 1991b;Betteridge et al 1999), and reduced leaf litter results in a reduction of aboveground water-holding capacity of the soil (Naeth et al 1991a), decreasing infiltration rate and increasing the volume of surface runoff. Management practices that reduce the total volume of surface runoff and encourage infiltration will reduce the potential for sediment and P losses from pastures (Gburek et al 2000).…”

“…Maintaining optimum pasture cover and allowing litter to accumulate on the soil surface can preserve forage plant vigor, improve soil structure, stabilize sediment, and reduce the movement of nutrients from pastures into streams (Naeth et al 1991b(Naeth et al , 1996Clary and Leininger 2000). Rotational stocking systems and hay harvest have been shown to reduce the amount of bare ground and maintain an adequate forage canopy in pastures, as opposed to continuous stocking, so that excessive soil erosion and nutrient transport to surface waters are prevented (Gilley et al 1996;Manley et al 1997).…”