Grazed Stubble Height as a Criterion for Controlling Sediment Production From Grazing Lands

Abstract

Efforts by state and federal agencies to develop standards and guidelines for protecting and enhancing water quality on grazing lands have led to suggestions that grazed stubble height criteria could be used to determine when cattle should be removed from a specific pasture or grazing area. Until recently only indirect scientific evidence from agronomy and laboratory studies gave support to the stubble height concept. Consequently, a grazing study was initiated on a Montana ranch in 1997 to determine the reduction in overland sediment achieved by grazing a pasture to a predetermined stubble height. Treatments consisted of 7 cm (3 in) grazed, 7 cm (3 in) clipped or mowed, 15 cm (6 in) grazed; 15 cm (6 in) clipped and untreated or natural forage plant height. The five treatments were used in a two-year trial spanning 1997 to 1999. At the conclusion of this study the magnitude of sediment production was related to the number of intense rain events during the March through June period rather than total precipitation. There was a significant year effect in terms of sediment accumulation (P < 0.01) but no year by treatment effect (P = 0.11). Even though a significant difference in sediment accumulation was detected between the shorter and taller stubble heights (P = 0.04) in both 1998 and 1999, the difference could not be explained by grazed stubble height alone. Close grazing (7 cm stubble) consistently ranked lowest in sediment production (P < 0.01) among all treatments, including the ungrazed control. These results suggest that changes in plant community structure and microtopographic caused by grazing influence sediment entrapment (retention) on hillslopes more than those caused by plant height.

Influence of mowing and narrow grass buffer widths on reductions in sediment, nutrients, and bacteria in surface runoff

“…The finding that mowing had no significant effect on runoff hydrology in both years was consistent with other mowing or clipping studies on grazing lands where water was applied by natural rainfall (Marlow et al 2006), simulated rainfall (Simanton et al 1991;Frasier et al 1998;Pearce et al 1998), or run-on distribution devices (Hook 2003). In contrast, other studies have reported lower hydraulic roughness coefficients of runoff for clipped than unclipped rangelands using rainfall simulators (Engman 1986), or lower roughness values for shorter than higher stem heights of different grass species using a run-on distribution device (Ogunlela and Makanjuola 2000).…”

“…These factors include plant litter (Engman 1986), plant canopy and basal cover (Weltz et al 1992), basal plant stem and litter cover (Abrahams et al 1994), buffer width (Pearce et al 1997), plant density (Ogunlela and Makanjuola 2000), biomass, cover or density of plants (Hook 2003), plant community structure and micro-topography (Marlow et al 2006), as well as stem diameter and plant density (Deeks et al 2012). Although plant height may influence sediment filtration when plants are inundated, a complex interaction of various factors is likely more important (Clary 2000).…”

“…Some studies have reported significant treatment effects of mowing or clipping (Engman 1986;Pearce et al 1997), while others found no effect (Simanton et al 1991;Pearce et al 1998;Hook 2003;Marlow et al 2006). The latter authors suggested that changes in plant community structure and micro-topography caused by grazing influenced sediment retention more than stubble height on rangelands.…”

Integrated Crop‐Livestock Systems and Water Quality in the Northern Great Plains: Review of Current Practices and Future Research Needs

“…The line in the box is the median, edges of the box are 25th and 75th percentiles, error bars are 10th and 90th percentiles, and points are values beyond the 10th and 90th percentiles. Data sources were Blanco‐Canqui et al (2016), Daniel et al (2006), Emmerich and Heitschmidt (2002), Marlow et al (2006), McEldowney et al (2002), Nustad et al (2015), Schepers and Francis (1982), Sheshukov et al (2016), and Wood and Wood (1988).…”

Biomass Production and Net Ecosystem Exchange Following Defoliation in a Wet Sedge Community

“…Transition to other, less denselyrooted facultative riparian species such as Kentucky bluegrass (Poa pratensis L.) can ultimately lead to bank degradation, loss of channel structure, decreased water availability for plant growth, and transition to upland plant communities (Winward 1994). Even in the absence of species change, livestock grazing or defoliation can reduce aboveground production of riparian plants (Boyd and Svejcar 2004), sediment filtration (Kauffman et al 1983), and modify soil properties (Marlow et al 2006).…”