Carbon Sequestration on Agricultural Land in Wisconsin Christopher Kucharik Center for Sustainability and the Global Environment (SAGE) The Nelson Institute for Environmental Studies University of Wisconsin-Madison November 12, 2008

The questions: What is terrestrial carbon sequestration and why is it connected to bioenergy feedstocks derived from agricultural land? Which land management options best promote C sequestration in agriculture? Can carbon sequestration on WI agricultural land mitigate C emissions?

The geographic extent of pre-settlement prairie

Croplands of North America Blended Census and Satellite Data Source: Ramankutty and Foley (1999)

Changes to Ecosystem Carbon Balance Prairie C fluxes Agriculture Fluxes Plant inputs Soil respiration Soil C pool Time (centuries) C Stocks Time (decades) C Stocks Soil C pool Plant inputs Soil respiration

What is terrestrial carbon sequestration ? The net removal of CO 2 from the atmosphere into long-lived pools of carbon. What is terrestrial carbon sequestration ? The net removal of CO 2 from the atmosphere into long-lived pools of carbon. Soil organic C roots trees

Carbon Sequestration Cost effective way to give us a 20 to 50 year time window to help curtail atmospheric CO 2 build-up until other alternatives to fossil fuel can be developed to de- carbonize global energy Landowners would receive payments in the future as local utilities/companies purchase “carbon credits” to help mitigate their emissions –Local programs are only voluntary at this point Chicago Climate Exchange (CCX)

Most Promising Agricultural Land Management Practices –Conservation Tillage (minimize disturbance) –Prairie and grassland restoration Conservation Reserve Program (CRP) Nebraska No-till corn WI CRP land

Corn Conservation tillage Conventional tillage

Corn Stover as a Biofuel Feedstock: Conservation tillage impacts 8 million mT in Wisconsin annually produced Provides structural stability to soil –Erosion prevention –Nutrient retention Increased residue reduces soil water loss and reduces soil temperatures Need to consider impacts to soil organic matter and productivity of cropping systems

Participants voluntarily remove environmentally sensitive (highly erodible) land from production for 10 or 15 yr contracts –Established in 1985 (Food Security Act); payment incentives –36.0 million cumulative acres enrolled in US –Largest U.S. conservation program on private lands –~534,000 acres in WI (2008); payments $50-100/ac Conservation Reserve Program (CRP)

Perennial Grasses as Biofuel Sources: Switchgrass, Miscanthus Extremely productive (2-4 m high) Can be used for electricity, heating, cooking or transportation (think cellulosic ethanol). Is renewable energy that can produce no net increase in global warming May store large amounts of carbon in plant roots, pulling further carbon from the atmosphere. Produces smaller amounts of nitrogen and sulfur oxides (both sources of acid rain) when burned for electricity

Biofuel feedstocks

WI Governor’s Task Force on Global Warming Recommendations Agriculture Sector –Encourage Prairie Plantings Current CRP acreage 533,830 acres (1/25/08) Plant grasses on currently cropped highly erodible land –3.1 million acres –Promote Improved Soil Management Practices Increase soil C storage through conservation tillage –Preserve existing C sequestration in CRP Avoid release of MMT CO 2 through 2028

Emerging market for Carbon Chicago Climate Exchange (CCX) – –Self-regulatory exchange; administers voluntary legally binding pilot program for reducing and trading GHG emissions in NA –Goals: Proof of concept Inform public and policy Provide leadership/opportunities Enhance reputations

National Farmer Union’s Carbon Credit Program (

Potential C Sequestration: State of Wisconsin Land use typeTotal Acres Soil CO 2 sequestered (tons) WI CO 2 + CH 4 Emissions % equiv 1. Conservation Reserve Program (rate: 1.0 mT CO 2 ac -1 ) 533, % 2. Highly erodible cropland converted to prairie/switchgrass (rate: 1.0 mT CO 2 ac -1 ) 3,100, % 3. All harvested cropland managed with conservation tillage (rate: 0.5 mT CO 2 ac -1 ) 8,928,0834,464, % 4. Idle cropland / pastureland (rate: 0.2 mT CO 2 ac -1 ) 3,135,259689, % Total15,697,0008,787, ,500,000 ( 7.7%) Units are metric tons C per year

Mitigating Automobile Emissions: Land use type Total WI AcresSequestered Soil C (tons) Equivalent Automobiles 1 % WI Registered Cars (2007) 2 1. Conservation Reserve Program (rate: 1.0 mT CO 2 ac -1 ) 533,830 97,4144.1% 2. Highly erodible cropland converted to prairie/switchgrass (rate: 1.0 mT CO 2 ac -1 ) 3,100, , % 3. All harvested cropland managed with conservation tillage (rate: 0.5 mT CO 2 ac -1 ) 8,928,0834,464,041814, % 4. Idle cropland / pastureland (rate: 0.2 mT CO 2 ac -1 ) 3,135,259689,757126,0985.3% Total15,697,0008,787,6281,603, % 1 CO 2 emissions per automobile = 5.48 MT CO 2 yr -1 ; EPA publication 420-F Wisconsin. Dept. of Transportation; 2,377,245 total automobiles

? Why could this trend be happening?

UW Agronomy Ph.D. student Gregg Sanford at GLBRC field trials in Arlington, WI

Five take home points Carbon credits are economic arrangements where businesses or individuals pay someone else to counterbalance their CO 2 emissions. For farmers and other landowners, growing bioenergy crops may increase future payments for carbon sequestration also. Buyers beware: the C offsets you pay for may not actually exist in nature. C mitigation is not a silver bullet to stop global warming. There are still good reasons to perform the management practices carbon offsets encourage -- they support increases in bioenergy feedstocks.