Livestock grazing and vegetative filter strip buffer effects on runoff sediment, nitrate, and phosphorus losses

Abstract

Livestock grazing in the Midwestern United States can result in significant levels of runoff sediment and nutrient losses to surface water resources. Some of these contaminants can increase stream eutrophication and are suspected of contributing to hypoxic conditions in the Gulf of Mexico. This research quantified effects of livestock grazing management practices and vegetative filter strip buffers on runoff depth and mass losses of total solids, nitrate-nitrogen (NO 3 -N), and ortho-phosphorus (PO 4 -P) under natural hydrologic conditions. Runoff data were collected from 12 rainfall events during 2001 to 2003 at an Iowa State University research farm in central Iowa, United States. Three vegetative buffers (paddock area:vegetative buffer area ratios of 1:0.2, 1:0.1, and 1:0 no buffer [control]) and three grazing management practices (continuous, rotational, and no grazing [control]) comprised nine treatment combinations (vegetative buffer ratio/grazing management practice) replicated in three 1.35 ha (3.34 ac) plot areas. The total 4.05 ha (10.02 ac) study area also included nine 0.4 ha (1.0 ac) paddocks and 27 vegetative buffer runoff collection units distributed in a randomized complete block design. The study site was established on uneven terrain with a maximum of 15% slopes and We speculate this shift to significantly higher runoff and contaminant losses from no grazing treatment combination plots during 2003 reflects the variability inherent to a complex and dynamic soil-water environment of livestock grazing areas. However, we also hypothesize the environmental conditions that largely consisted of a dense perennial cool-season grass type, high-relief landscape, and relatively high total rainfall depth may not necessarily include livestock grazing activities. (Downing et al. 2000;James et al. 2007) and have higher P losses than ungrazed pastures (Gillingham and Thorrold 2000). Nitrogen (N) losses from agricultural/grazing fields to surface and subsurface waters also have been documented (Madramootoo et al. 1992; Sauer et al. 2000;Stout et al. 2000). Studies have indicated that N and P losses from continuously grazed pastures are generally higher than rotational grazing and ungrazed pastures (Ritter 1988;Mathews et al. 1994).Although livestock grazing activities generally have been reported to adversely impact the hydrology of pasture areas, Sharpley and Syers (1976) determined that P transport due to grazing animals was significantly less than P losses from fertilizer addition. Nash et al. (2000) found that cattle grazing did not result in large stores of available P compared to P fertilization. Mathews et al. (1994) Vegetative filter strip buffers are bands of vegetation located downslope of cropland, livestock grazing areas, and other potential sources of surface runoff and contaminants (Dillaha et al. 1989). Vegetative buffers provide erosion control and filter nutrients, pesticides, sediment, and other pollutants from agricultural runoff by reducing sediment carrier energy. Contaminant re...

Simulation of watershed hydrology and stream water quality under land use and climate change scenarios in Teshio River watershed, northern Japan

“…The increase of riparian zones along all streams can be possible mitigation option to buffer contaminants entering via surface runoff from farmland and ameliorate water quality impacts resulting from increased fertilizer application (Johnes and Heathwaite, 1997;Webber et al, 2010Lal et al 2011. Since riparian zones are prominently located between terrestrial and aquatic ecosystems, riparian processing of nutrients is very effective despite occupying a small area of land relative to the entire catchment.…”

Implementation of BMP Strategies for Adaptation to Climate Change and Land Use Change in a Pasture-Dominated Watershed

“…Different approaches to mitigate animal waste problems were adopted in the Rural Clean Water Program (RCWP) projects conducted in the American states of Utah and Florida due to their different climatic characteristics [2]. Multiple BMPs are usually combined together in a watershed, such as tillage and nutrient management practices [3] or grazing management and vegetative buffers [4] to effectively control pollutants from various sources. When numerous BMP options are available, whether various combinations of BMPs work synergistically or cancel the effect of each other when implemented together in a watershed must be evaluated [5,6,7].…”

Comparing different types of rural landowners: Implications for conservation practice adoption

“…For instance, studies have shown high nutrient levels in runoff from horse paddocks and pastures grazed at high stocking rates (Airaksinen et al 2001;Parvage et al 2011). Moreover, livestock (cattle, horse, and sheep) manure often contains high levels of E. coli (Escherichia coli) (Weaver et al 2005), and livestock grazing, in general, causes nutrient runoff and the sedimentation of waterways (Webber et al 2010). Though individual small farms and rural residences have less of an individual impact on environmental quality than individual large farms, the overall impact of small-scale rural landowners grows as they increase in numbers and change land use patterns.…”