by Tamara Scully
At the Young Farmers Conference 2017, Kelly Mulville, of Paicines Ranch near San Jose, CA, addressed the benefits of merging livestock and crop cultivation with the goal of enhancing soil health, reducing disease and pest pressures, increasing the ability to farm without irrigation, enhancing carbon sequestration, and producing healthy food. At the ranch, the 7,600 certified organic acres are a part of an overall plan to mimic nature, as Mulville designs resilient farming systems which harness solar energy, and require few off-farm inputs.
The goal is to “utilize solar energy and livestock and grazing and green plants to cycle carbon into the ground and build soil health. How do we get carbon cycling from the atmosphere and back down into the soil? The principles are going to be the same anywhere,” Mulville said.
Vineyards for sheep
Sheep have grazed vineyards historically, and re-introducing sheep as a vineyard management tool can enhance the entire system. Proponents claim integrating livestock grazing into the vineyard, vines will have higher yields, fruit will be more nutritious, soil will retain more water and require less irrigation, and fertilizer will be applied naturally in the form of manure.
It’s all about “looking at the vineyard from the perspective of sunlight,” Mulville said. “How do we design these systems to work for grazing?”
In most traditional vineyard grazing systems, the sheep graze only during the dormant season. That’s because grape leaves are very tasty to sheep. And, since sheep are normally set-stocked, rather than rotationally grazed in the vineyard setting, overgrazing is problematic.
To avoid these issues, Mulville designed the ranch’s new 25 acres of vineyards explicitly to be grazed by the sheep flock. The site was leveled out, and one-sixteenth of an inch of compost added. Cover crops were then planted and grazed, utilizing planned grazing techniques.
“When we’re doing planned grazing we’re looking at what the carrying capacity of our land is,” Mulville said.
Three hundred animals per acre was their typical density, using net fencing to adjust stocking and rotate grazing as needed. Livestock guardian dogs provided protection from predators.
The first year, Mulville reports the flock harvested the forage equivalent of six animal days per acre. By the second season, the organic matter in the soil had increased significantly, and the amount of forage harvested by the flock was the equivalent of 67 animal days per acre. A third-party is monitoring the soil health in the system. During the first two years of grazing, the soil organic matter was increased by one percent per year, and water holding capacity increased by 320,000 gallons on 12 acres.
They then ran sheep through the acres prior to planting to wine grape vines.
The vineyard design is a bit unusual to accommodate extended season grazing by the sheep and to promote soil health.
“In a typical vineyard, your vines are going to be vertical. And we just decided to go up and go horizontal. We raised the fruiting zone up to be out of reach of the sheep. We’re spreading the vines out a little bit to increase the shade,” Mulville said.
Raising up the vines also decreases the chance of frost damage. And, with drier and hotter growing seasons, the shade created by the vines in this canopy system helps cool the fruit, too. The vines are planted in rows spaced 12 feet apart, with vines at six-foot intervals. This is an increase in vines per square foot from they typical vineyard layout.
Realities of vineyard grazing
Small vines can be protected from the sheep, and established vines will not be damaged. Grazing has also eliminates the need for tractors in the vineyard, reducing soil compaction, and reducing the need for irrigation by up to 90 percent. No outside fertility is required when sheep graze the vineyard. The sheep also harvest the suckers from the vines, eliminating the hand labor needed for that task. Water is provided for the sheep on lines separate from the irrigation system.
Sheep are trained to an electric fence, and left in the vineyard until just prior to harvest. This was, at first, a food safety concern, and organic certification required that the animals be removed 90 days before harvesting. That has changed, and their certifier now allows grazing until harvest, because “no pathogens are surviving alcoholic fermentation,” he said.
Mulville also noted that research at the University of California-Davis has shown that pathogenic activity decreases as soil quality increases. When cover crops are grown and then tilled up, 80 percent of the carbon is lost, and the soil is damaged. Instead, the cover crops can be grazed by the sheep, sequestering that carbon and enhancing soil health.
“Grazing animals impart disease and pest resistance to the plants they are grazing,’ Mulville said.
A trial conducted on the ranch estimated that the cost savings of utilizing sheep in the vineyard is at least $450 per acre per year, although Mulville believes the actual savings will be higher.
“You’re getting away from a high input system and looking at how you use sunlight and living organisms to manage your land,” Mulville said. “If you can graze 50 percent or less, than the plant is still able to continue cycling carbon into the ground.”
The ranch is currently leasing 570 acres of irrigated cropland to a large organic grower. But the soil is not healthy, and they are gradually taking back the land and planting it to forages. The plan is to grow a mix of annuals and cover crops, using no-till seeding, and then grazing cattle and sheep.
After a few years, the soil should be healthy enough to support perennial crops. They plan on growing apricots, mulberries and persimmons, providing grazing animals with some shade.
“We’re going to be planting trees every 120 feet in these long strips,” he said.
Mulville is interested in growing vegetables in an integrated livestock grazing system. In the past, he has grazed cattle in a central pivot design, with pie-shaped wedges of paddocks, and had no-till seeded one of those paddocks with 60 varieties of vegetables, successfully. Because of the intensively-managed grazing prior to planting, weeds were not a problem.
“It’s easy to do the no-till for forage, but as we’re learning to do the vegetables, it will be harder,” he said.
According to data from the National Resources Conservation Service (NRCS), and shared by Mulville, a comparison of water infiltration rates under different land uses demonstrates the soil health benefits of intensively managed, planned grazing systems. Continuous season-long grazing systems were able to drain one inch of water in seven minutes, a vast improvement over the 31 minutes required for the same soils planted to no-till corn for one year. But a well-managed planned grasslands grazing system improved the infiltration of water, requiring only 10 seconds to drain that inch.
“This is really what’s telling me why we need to integrate livestock into cropping practices,” Mulville said.
The complete video of the conference seminar can be viewed here: www.stonebarnscenter.org/resource/integrating-livestock-cropping-systems/.