Sequestering atmospheric carbon in soil with new ranching approach

By RICHARD MARK GLOVER

MARFA – Marathon rancher and Sul Ross State University professor Dr. Bonnie Warnock will lead a tour of the Mimms Ranch on Sunday in conjunction with the Marfa Dialogues: Politics and Culture of Climate and Sustainability. Warnock intends to illustrate how advanced management can reduce the carbon footprint of cattle ranching.

“There is the idea out there that cattle production is not compatible with certain environmental goals,” said Warnock, professor of Natural Resource Management.

In fact, according to the U.S. Environmental Protection Agency, ruminant livestock (cattle, sheep and goats) with their special digestive systems, contribute 80 million metric tons of methane into the atmosphere each year, or 28 percent of the human generated total. Methane, carbon dioxide, water vapor, ozone and nitrous oxide are identified by scientists as the primary greenhouse gases. With their increase, a hotter planet seems inevitable as evidenced by the National Oceanic and Atmospheric Administration release this week that July 2012 marks the 36^th consecutive July and 329^th consecutive month with a global temperature above the 20^th century average.

Some pundits of the food industry are suggesting a move away from an animal protein diet to a plant protein diet. Energy costs in livestock production, including the affiliated carbon footprint, can be 10 times higher than the production of plants.

But according to the Worldwatch Institute, meat consumption is on the rise worldwide, and as good rains bless the TransPecos, ranchers may find no reason to change their stock and trade, though new techniques might bring more sustainable venues to the cattle ranching industry.

“We want to focus on how grassland cattle production is tied to carbon sequestration and show that certain types of grazing systems under a holistic management approach can provide conduits that take (carbon dioxide) out of the atmosphere and sequester it in the ground,” said Warnock.

As any rancher will tell you, they’re not only in the livestock business but also in the grass business, and stimulating grass growth is good for profit. Warnock notes that’s good for the environment, too.

“There is so much carbon dioxide in the atmosphere,” said Warnock. “It is contributing to climate change, but plants using photosynthesis capture that carbon and sequester it in the soil where it can be held for long periods of time, from one to 300 years.”

At the Mimms Ranch, just north of Marfa and now owned by the Dixon Water Foundation, cattle are directed by a series of electric fences to move between paddocks (traps) every one to 10 days.

“This practice stimulates grass and forbs growth. The grazing makes the grasses healthier, kind of like mowing your lawn,” said Warnock. “The healthier the grass, the better the conduit. Photosynthesis converts the carbon in the atmosphere to sugar and starches that are used by the plants for root growth and as the roots die off and renew they become part of the organic (carbon) material of the soil.”

Warnock suggests the quick paddock rotation method is similar to earlier days when big herds of wild bison roamed the plains, grazed, defecated, and moved on.

One of the criticisms of the methods is the cost of infrastructure. Many short term paddocks (traps) that are used only one to 10 days per year means a lot of land is required. But certain efficiencies are realized including planning the rotation to end near the loading pens at market time.

“It’s less stressful on the animals,” said Warnock.

Warnock is also working on the Native Plant Project.

“We’re collecting seeds from natural grasses and forbs in the TransPecos,” said Warnock, who earned her PHD from Texas A&M University in soil science with an emphasis in soil restoration. “We’re growing these seeds in test plots in Alpine, Imperial and Uvalde to calculate their performance in different areas. We’re hoping to make Trans-Pecos native plant seed available commercially.”

At the O2 Ranch, she continues to work on the grassland restoration project where they’ve grubbed mesquite and poisoned creosote with Spike to bring back native grasses and forbs like side oat grama, bush muhly, burrow grass, tabosa, trailing ratany and perennial sunflowers.

“Spike (a herbicide) kills creosote but it’s also killing some of the desirable forbs,” Warnock said. “We’ve stopped using it in favor of mechanical methods.”

Her latest project in conjunction with SRSU, where attendance is up at the School of Agriculture and Natural Resource Sciences, is at the Mimms Ranch. The ranchland was nearly completely burned in the Rockhouse fire, the state’s second largest wildfire in history.

“We’re monitoring birds, small mammals, and plants,” she said. “Just started the field collections. Hope to see how they’re recovering from the fire and how they’re interacting with the livestock that have just been brought back. We’re also looking at the microbial community in the soils.”

The Mimm Ranch tour starts at 9am Sunday at the south gate to the ranch, located at the end of Austin Street in Marfa.