Benefits of increasing grazing height on weed suppression in grass based grazing systems

Project Overview

Project Type: Graduate Student
Funds awarded in 2009: $9,199.00
Projected End Date: 12/31/2010
Grant Recipient: University of Wisconsin
Region: North Central
State: Wisconsin
Graduate Student:
Faculty Advisor:
Dr. Mark Renz
University of Wisconsin

Annual Reports


  • Animals: bovine, goats, sheep
  • Animal Products: dairy


  • Animal Production: grazing management, grazing - rotational, preventive practices
  • Education and Training: focus group, on-farm/ranch research, participatory research
  • Farm Business Management: whole farm planning
  • Pest Management: cultural control, weed ecology
  • Production Systems: organic agriculture, transitioning to organic


    The benefits of increasing grazing height on weed suppression in management-intensive rotational grazing systems in Wisconsin

    While the goal of Extension personnel is to ensure research findings are disseminated to the public, often obstacles that hinder adoption are not clearly understood. In pastures many factors limit adoption of new research including research conducted at research facilities exclusively. This often limits interaction and collaboration with private farmers and can reduce adoptability of new practices. We conducted weed suppression experiments on research farms and private farms to evaluate how similar the results would be. While private farms had a yield advantage when compared to research farms, differences between treatments were similar. Working with private and research farms in combination with electronic surveys and focus groups were found to be a sufficient tools to address both the awareness of research as well as obstacles that prevent adoption of new weed suppression methods in pastures.


    Weedy pastures have been shown to have reduced forage quantity, quality, and utilization by animals (Seefeldt, Stephens, Verkaaik, & Rahman, 2005). Although herbicides exist to manage these weeds many land managers avoid applications due to cost of application, impact to desirable legumes in their pasture, and banned use in organic pastures. Increasing the residual grazing height is one management option that could become an effective option for weed management in pastures in the upper Midwest. Research has shown that increasing the residual grazing height from 5 cm to 15-20 cm can suppress common pasture weed seedling density by 61-67% (Schmidt & Renz, 2010a, 2010b) in management-intensive rotational grazing (MiRG) systems.

    However, this prevention was associated with a significant loss in forage quantity, when compared to common grazing practices in pastures in the upper Midwest. A focus group was conducted in the fall of 2009 to address concerns over forage yield reductions with weed management methods. The group designed two additional treatments to test in 2010 to mitigate forage loss, while still obtaining adequate weed suppression (Schmidt & Renz, 2010a). As farmer adoption of agronomic practices is dependent on many factors (Doll & Jackson, 2009; Pannell et al., 2006) we wished to determine what threshold of yield loss would prevent adoption of weed management methods by surveying MiRG farmers. Others have shown that participatory on-farm research can yield different results compare to research farms (Bell, Lyon, Gratton, & Jackson, 2008; Jackson, Bell, & Gratton, 2007). We wanted to determine if these differences were evident with weed suppression methods in MiRG systems in the upper Midwest. Specifically, the objectives of this paper are to evaluate if weed suppression methods involving increasing residual grazing heights are practical to adopt on farm and if results were similar between research farms and private farms. Additionally, we wished to survey MiRG farmers about weed management methods currently utilized to direct future research.

    Project objectives:

    Expected short-term outcomes will develop an understanding of how producers can balance suppression of weed seedling emergence with potential reductions in forage yield and quality by altering grazing heights. These outcomes will be directed towards the members of the focus group.

    Intermediate outcomes will include the extension of this information to grazing networks and sustainable agriculture organizations as well as publication in peer reviewed journals. This information will include a discussion of the mechanisms we determined to suppress weed seedling emergence and how it can be applied to a range of grazing production systems (e.g. beef production, sheep production, dairy).

    Long-term outcomes include a better understanding of how to use cultural practices to not only prevent weed emergence, but balance this prevention with forage quantity and quality. This research also has the potential to be useful in other areas where weed seedling suppression is desired, such as restorations in natural areas, or weed management for programs such as Conservation Reserve Program (CRP).

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.