Using sheep to graze vineyards has many benefits including lowering the carbon footprint, fewer tractor passes, and reduced herbicide use. Kelsey Brewer, Ph.D. Candidate at the University of California at Davis has been researching how these living lawnmowers impact nutrient and energy flows in the eco system.

When tractors were replaced by sheep, the research team found that vineyards had 1.3 times more organic matter and nitrogen plus twice as much available soil nitrogen in the soil. Grazed vineyards have very high microbial activity, improved infiltration, and porosity. Of course, sheep are not a good fit for every vineyard system. Their benefits are not seen in ranches where heavy tillage is still used. While a manager could establish their own flock, most grazing is contracted with experienced professionals who can intensively and efficiently graze in vineyard.

References:

107: How Grazing Sheep Can Benefit Your Vineyard

Sustainable Winegrowing