Targeted grazing involves the use of specific kinds of livestock to reduce populations of certain targeted plant species and enhance the growth of the more desired plants. This approach has advanced the use and understanding of grazing as a beneficial practice that can enhance the plant community’s composition, desirability and production of forage on a specified land area.
Most targeted grazing strategies have included relatively high stock densities and short grazing durations, which are often needed to attack the problem plant at its most vulnerable stage of growth. In some situations, the short grazing windows and high stocking densities required for effective control of the targeted plant species limit the amount of land that can be treated in any one year. Assembling a large enough herd for a short part of the grazing season can be a great challenge.
Two grazing trials were conducted on annual grassland in northern California to evaluate how different combinations of stocking density and grazing duration influence the population of medusahead, native plants and non-native desirable plants. A report on this trial is included in the July 2017 issue of Rangeland Ecology and Management, a publication of the Society for Range Management.
One trial was conducted using yearling heifers grazing on gently sloping foothill land in Glenn County. The other was conducted with dry ewes grazing on relatively level land in Yolo County.
The yearling heifer trial included a low density/long duration (2.6 animal units per hectare for 21 days) grazing and a high density/short duration (4.5 animal units per hectare for 14 days) grazing. Both grazed at a stocking rate of 1.9 AUM per hectare. A hectare is 2.47 acres.
The trial with dry ewes included a low density/long duration (4.1 animal units per hectare for 30 days) grazing and a high density/short duration (8.1 animal units per hectare for 16 days) grazing at a common stocking rate of 4.1 AUM per hectare.
Previous research with targeted grazing of medusahead used stocking densities of 100-200 animal units per hectare and grazing durations of 1-2 days, which are impractical for a normal production scale. This study showed that targeted grazing with stock densities and durations that are feasible under production conditions were successful in achieving the goals of the targeted grazing plan. This result was obtained with both cattle and sheep.
The knowledge base for targeted grazing has been increasing for decades and supports the use of planned grazing in addressing critical natural resource problems that exist around the globe. Animal production practices and other logistics may place constraints on how targeted grazing can be applied, therefore it is important to understand how the benefits from this practice will change due to the components of the targeted grazing strategy.
This study suggests that more extensive work should be done on how small but strategic changes in the parameters of a targeted grazing plan can alter the benefits from grazing. While the finer points of the targeted grazing strategy need more work to be done, this study adds more support to the use of managed animal grazing as a significant tool for improving grasslands.
Producers interested in developing their own targeted grazing plan may obtain advice from their local NRCS Range Management Specialist or Extension Range Management Specialist.
Doug Warnock, retired from Washington State University Extension, lives on a ranch in the Touchet River Valley where he writes about and teaches grazing management. He can be contacted at email@example.com.