Assessing the Impacts of Mob Grazing in Southern Oregon

Assessing the Impacts of Mob Grazing in Southern Oregon

Summary

This project is analyzing the effects of mob grazing on pasture and soil health. Mob grazing is being compared to management intensive grazing and a control, which is either animal exclusion (no grazing) or season-long/continuous grazing. One location is using sheep and the other locations are grazing cattle with a minimum stocking rate of 200,000 pounds per acre equivalent. We experienced a very dry year this year and the irrigation season was shortened at three of the locations. Treatments continued last year until killing frost. This year has been very warm and producers moved to their winter management prior to killing frost; movement to witner management constituted the end of the grazing season for this study.

Objectives/Performance Targets

1. Define mob grazing based on an upper and lower limit of animal pounds per acre and a minimum recovery period to standardize regional discussions among producers (April 2013 ).
2. Implement grazing treatments at three locations across Southern Oregon. Each location will have three replicates of three treatments: 1. Mob grazing, as defined by the project; 2. Current grazing practice of producer; and 3. Control, no grazing exclosure (May 2013).
3. Collect site specific information at each of the farms, including management history, climate, aspect, slope, and soil texture, pH, type, bulk density, and baseline data (May 2013).
4. Collect soil and forage data for three years (May 2013-October 2015), including:
   1. Total annual forage production
   2. Pasture species richness and abundance
   3. Total soil organic carbon and nitrogen
   4. Annual soil biological assessment, including active and total bacteria and fungi, protozoa, and nematodes.
   5. Additional soil parameters –pH, bulk density, and infiltration rates
   6. Soil moisture content
5. Statistically analyze results to determine treatment effects on forage production, forage species diversity, and soil parameters. (December 2015).
6. Provide site tours pre- and post- mob grazing. Combine site tours with training in use of soil quality scorecards and pasture assessment tools (July 2013, July 2015).
7. Present study results to producers regionally. Survey producers for interest in adoption of mob grazing practices (October 2013, October 2014, October 2015).
8. Develop a fact sheet summarizing the results of this study (December 2015).

Accomplishments/Milestones

1. Up to this point, all sampling and sample analysis has been done with minor changes. However, the lab selected to complete the benchmark soil analyses for each site had a complete breakdown of one of their analyzers, followed by closure of the lab and loss of some of our samples. We are still trying to track the lost samples. All the samples found to date have been sent to a new lab and we are waiting for analysis results.
2. We have completed two grazing years of the study (producers do not mob graze from killing frost until March or April depending on their rotation). Although not all analyses are complete nor have statistics been done, we do have several observations that seem consistent across sites:
   1. The mob sites have more soil life, especially earthworms at those sites with clay soils.
   2. It is far easier to insert a soil sampler into the soil at the mob sites than MIG or control sites, especially at those locations that have clay soils.
   3. The mob sites tend to have more seedlings, especially of warm season grasses (one location).
   4. The mob sites tend to have less bare soil due to seedlings and/or tillering (one location).
   5. Pheasant populations have increased (one location).
3. A workshop was held September 27, 2014 to review the concept of mob grazing, research, and anecdotal reports of benefits and to introduce participants to our study. In the afternoon, we toured two of the locations and had the participants evaluate soil health using the ATTRA soil health score card and compare mob grazing to management intensive grazing. Participants indicated they could tell a difference in compaction and soil infiltration between the sites.
4. The producers practicing mob grazing on their property have indicated that they have observed benefits. One producer said “this trial has caused me to reevaluate some of my practices and the changes I’ve made have helped improve the productivity of my farm.” Another producer indicated that the results he’s seen so far in the study has caused him to “graze taller” across his farm (except the MIG plots in the study), leading to increased production and better plant density. He also used mob grazing in a non-study area and says that the area looks better than it has in 20 years. However, all the producers in the study feel that in our climate on irrigated land, true mob grazing is probably best used as a tool to achieve a specific purpose on a specific plot of ground rather than a method of grazing to be used all the time across the farm.

• Taking forage samples
• A mob plot after treatment
• Mob Grazing Workshop

Impacts and Contributions/Outcomes

Increased awareness and study of plants and soil on the subject farms has led to improvements in grazing management and productivity beyond the study plots

Increased awareness of the potential tool of mob grazing

Awareness and appreciation of grazing as a tool to improve soil health and plant communities

Collaborators: