Land Management and Carbon Sequestration

As we all know, the current carbon dioxide (CO2) storage imbalance between the atmosphere stock and the ground storage stock is an imminent and immediate threat to our world’s economies and ways of lives. Removing carbon from our atmosphere via carbon sequestration has a questionable history; unlike dumping vast amounts of iron into the ocean to simulate whale excrement (compliments of Russ George and the HFRC), a more simplistic, ecocentric, and commonsense method of carbon sequestration was discussed in the chambers of the Longworth office building of the Unites States House of Representatives this past Wednesday. The Committee on Natural Resources Subcommittee on Public Lands and Environmental Regulation hosted a hearing on carbon soil sequestration or “carbon farming” and heard testimony from an ecologist’s, rancher’s, and scientists’ viewpoints supporting the emerging area of sequestration study.  

Looking back to past centuries, land-hungry pioneers explored westward across the United States, encountering a vast landscape of towering grasses that nurtured deep, fertile soils. The tall grass prairies were then a thriving ecosystem, host to birds, rodents, grazing herds and more.  Today, just three percent of North America’s tall grass prairie remains. This ecosystem’s disappearance has had an obvious impact on the landscape and ecology of the U.S., but a less-known consequence of the terrestrial transformation has largely been overlooked: a massive loss of soil carbon into the atmosphere. According to Rattan Lal, director of Ohio State University’s Carbon Management and Sequestration Center, the world’s cultivated soils have lost between 50 and 70 percent of their original carbon stock, much of which has oxidized upon exposure to air to become CO2.

Many scientists believe that regenerative agricultural practices can turn back the carbon clock, reducing atmospheric CO2 back to preindustrial levels while also boosting soil productivity and increasing resilience to floods and drought. Regenerative techniques studied include planting fields year-round in crops or other cover, using agroforestry, polycultures, and rotational grazing patters. Rotational grazing pattern plans is the most relevant and feasible technique for improvement of vast expanses of federally managed land. As expanded upon by Dr. Richard Teague in the hearing, when left to their own devices cattle pick their favorite spots to graze and overgraze, not playing the symbiotic grazing role of roaming herds of bison, elk, and pronghorns. Dr. Teague went on to talk about the “sweet spot” of herbivory, and how both over and undergrazing are damaging to grassland ecosystems. Grassland plants have evolved to rely on grazing to make way for new growth and recycle nutrients back into the soil via manure. Undergrazing will limit new plant growth due to lack of accessibility to sunlight and increases the risk of fires. With tall, dry, ungrazed grass covering a plain a wildfire can sweep through and devastate the soil. Overgrazing will prevent perennial plants from healthy regeneration and will dry out the soil due to lack of cover. This lack of cover critically impacts the fungi in the soil—major players in the soil ecosystem.

Root, or mycorrhizal, fungi governs the nutrient transfer between plants and soil. According to Australian soil scientist Christine Jones, plants with mycorrhizal connections can transfer up to 15 percent more carbon to soil than their non-mycorrhizal counterparts. Mycorrhizal fungi commonly have threadlike filaments called hyphae that extend the reach of a plant, increasing access to nutrients and water. These hyphae are coated with a sticky substance called glomalin, discovered only in 1996, which is instrumental in soil structure and carbon storage. The U.S. Department of Agriculture advises land managers to protect glomalin by minimizing tillage and chemical inputs and using cover crops to keep living roots in the soil. In research published in Nature in January, scientists from the University of Texas at Austin, the Smithsonian Tropical Research Institute, and Boston University assessed the carbon and nitrogen cycles under different mycorrhizal regimens and found that plants linked with fruiting, or mushroom-type, fungi stored 70 percent more carbon per unit of nitrogen in soil. Under current management practices, overgrazing and lack of soil coverage lead to a significant decrease in fungi productivity.

There are currently farms and projects with the goal of efficient carbon farming. Hearing panelist Mr. John Wick spoke about the Marin Carbon Project (MCP), a consortium of ranchers and land managers, researchers, extension specialists, non-profits, and local and federal agencies working on improving rangeland productivity and sustainability, which he co-founded. Every year, Wick produces more than 50,000 pounds of grass-fed beef on land that was once considered heavily degraded. He helped restored the productivity of the MCP land by replenishing the soil carbon content under the guidance of Dr. Jeffrey Creque, a rangeland ecologist and Dr. Whendee Silver a biogeochemist from UC Berkeley. Spreading manure works to fertilize the soil but raises pollution and public health issues, and releases greenhouse gas via respiratory bacteria. These problems are largely taken care of when the manure is composted. After a one-time ½ inch compost application in 2008 to Wick’s ranch, the MCP has measured a 50% increase in forage production for the last 5 years. Models showed that this will likely continue for decades as the compost continues to slowly break down, with all the co-benefits associated with increased soil carbon, including drought resistance and less erosion. Scaled to just 5% of California’s grasslands each year, this practice would offset all of the state’s annual agricultural and forestry emissions. For reference you can access Mr. Wick’s written testimony here.

There is legal precedent for the Department of the Interior, and subsequently the Bureau of Land Management, to take action and implement policies that would greatly improve the quality of federally managed soil. Such precedent can be found in the Taylor Grazing Act of 1934, Title IV of the Federal Land Policy and Management Act of 1976, and in certain cases, the Endangered Species Act of 1973. Exemplary federal law on grazing policy is relevant to west coast states in 43 U.S. Code § 1181d, which asserts that “the Secretary of the Interior is authorized, in his discretion, to lease for grazing any of said revested or reconveyed…[and] further, that the Secretary is also authorized to formulate rules and regulations for the use, protection, improvement, and rehabilitation of such grazing lands.” Congressional action in the form of an amendment or bill requiring the Department of the Interior to account for carbon sequestration in land management would lead to historic improvements in our federally managed land.

Land rehabilitation techniques are now well understood, and land rehabilitation has the distinct benefit of sequestering atmospheric carbon back into the soils that once hosted it. There is commonsense, low-cost, and desperately needed solution to carbon sequestration staring our government in the face. The EDN calls on Congress to take action and install better land management policy to help restore our nation’s once great tall grass prairieland, and help sequester carbon to mitigate the impacts of global climate change. 

Author: Ben Criswell, EDN Intern