Vines And Ovines: Benefits of Target Grazing to Sheep and Vineyard Industries

Final Report for FW14-024

Project Type: Farmer/Rancher
Funds awarded in 2014: $14,991.00
Projected End Date: 12/31/2016
Region: Western
State: California
Principal Investigator:
Jaime Irwin
Kaos Sheep Outfit
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Project Information


Vines and Ovines: Benefits of target grazing to sheep and vineyard industries was designed to initiate scientific research that supports the symbiotic relationship between vineyards and sheep management. The project investigated the environmental and economic impacts of target sheep grazing as a sustainable agricultural practice in vineyard management. The project looked specifically at soil health and vineyard floor management. A main concern for many vineyard managers was soil compaction. We have found that sheep have little to no influence on soil compaction.

Kaos Sheep Outfit is one of the first companies in the United States to commercially graze sheep in vineyards. We own 1000 breeding ewes and run about 3,000 feeder lambs, in the fall and winter months, in vineyards and other agricultural lands. We have proven to be competitive with tractors, but would like to add to our sustainability as a company by providing valid research highlighting what sheep are or aren’t doing on the lands they are grazing. Our preliminary research has determined that there was little to no positive or negative impact to grazing sheep in vineyards. We would like to continue the research for another two-five years to be able to come to a more conclusive conclusion.


We divided the 9.69 acre research plot at the Bonterra McNab Ranch into eight plots, four grazed and four un-grazed. We used a stocking density of 38 sheep an acre in the plots that were grazed. The soil analysis looked at Organic matter, Phosphorus, Potassium, Magnesium, Calcium, Sodium, pH, Hydrogen, Cation Exchange Capacity and percent cation saturation. We looked at bulk density, forage yields and soil porosity to see what impacts the sheep had on vineyard floor management. Pruning weights before and after the sheep grazed were cut and weighed to see if there was a difference in vine health and performance.

Project Objectives:

1. Plot design: McNab Ranch, Plots 2A, 2B, 2C, and 2D. Total of 9.69 acres divided into 8 different research plots, four that were grazed and four that were un-grazed. The plots are well established and documented at the site and on maps.

2. Soil Health and Carbon Sequestering: The soil analysis shows what was found in the soil before and after the sheep grazed in all research plots. This analysis shows Carbon levels as well.

3. Virginia Creeper Leafhopper Data Collection: This data collection was not accomplished in 2015.

4. Grape Production: This was accomplished by looking at pruning weights pre and post grazing.

5. Vineyard Floor Measurement: Forage samples were taken and analyzed

6. Vineyard Floor Management: Bulk Density samples were taken

7. Educational Outreach: California Fibershed convention, American Biodynamic Convention, and video widely spread throughout the sheep and vineyard industries.


Click linked name(s) to expand/collapse or show everyone's info
  • John Harper
  • Glenn McGourdy


Materials and methods:

The soil analysis included taking 50 random samples, six inches deep from each of the eight plots. The soil samples from each plot were mixed to make one sample from each plot that was sent to A & L Western Agricultural Laboratories. A & L Laboratories Soil Analysis report included Organic Matter, Phosphorus, Potassium, Magnesium, Calcium, Sodium, Ph, Hydrogen, Nitrogen, Sulphur, Cation Exchange Capacity and percent Cation Saturation.

Viticulturist Glenn McGourdy, with UC Davis Extension, collected bulk density, forage and soil porosity data.

Pruning weights from the vines were gathered randomly from each plot in January 2015 before the sheep grazed and then post in January 2016 after the sheep grazed.

Research results and discussion:

Outcomes and Impacts are in the attached document

Our findings do not show that there are positive or negative impacts to having sheep grazing vineyards at a rate of 38-sheep/per acre. There is little to no scientifically significant difference in the organic mater, soil nutrients, bulk density or soil porosity. The sheep consumed about half of the forage yields. The pruning weights showed that the vines in the plot were not at uniform condition to start and so the data collected is not conclusive.

Bonterra Sheep Trial Results

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

PowerPoint presentation about research at Biodynamic Conference. Video and PowerPoint about research at the CA Fibershed Conference. A high quality video was made highlighting the agricultural partnership that vineyards and sheepherders can have and the research that is being done to aid in long-term stability to this partnership.

Education and Outreach Outcomes

Recommendations for education and outreach:

Potential Contributions

This information will hopefully put to rest some vineyard manager and sheepherder concerns about grazing sheep in vineyards. More sheep can graze vineyards, which can benefit both industries. We got a call last week from a sheepherder who is going to graze a vineyard in Sonoma County this year and he was asking about the research we found, because the vineyard managers had some questions. To me, this is our largest accomplishment and contribution.

Future Recommendations

More research needs to be done.

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.