Projected economic benefits of renewable energy derived from a native prairie grass, switchgrass, include nonmarket values that can reduce net fuel costs to near zero. At a farm gate price of $44.00/dry Mg, an agricultural sector model predicts higher profits for switchgrass than conventional crops on 16.9 million hectares (ha). Benefits would include an annual increase of $6 billion in net farm returns, a $1.86 billion reduction in government subsidies, and displacement of 44-159 Tg/year (1 Tg ) 10 12 g) of greenhouse gas emissions. Incorporating these values into the pricing structure for switchgrass bioenergy could accelerate commercialization and provide net benefits to the U.S. economy.

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I We collected soil samples from 27 study sites across North Central UniTed States to compare the soil carbon of short rotation poplar plantations to adjacent agricultural crops and woodlots. Soil organic carbon (SOC) ranged from 20 : o more than 160 Mgha across the sampled sites. Lwest SOC ieieis were found in uplands and highest levels in riparian soils. We attributed differences h bulk density and SOC amcng cover types to the inclusion of woodlot soils in the arilysis. Paired comparison found few differences between poplar and agricuitura! crops. Sites wi ;h significant comparisons varied in magnitude and direction. Rela?s$ely greater SOC was often obsewed in poplar when native soil carbon was low. but there were impoeani exceptions. Woodlots consistently contained greater SOC than the other crops, especially ar depth. We obsewed little difference between paired poplar and switchgrass, both promising bioenergy crops. There was no evidence of changes in poplar SOC relative to adjacel?! agricultural soils when considered for stand ages up to 12 years. Highly variable native SOC levels and subtle changes over time make verification of soil carbon sequestration among land cover types difficult, In addition to soil carbon storage potential, it is therefore impo'tant to consider opportunities ofered by long-term sequestration of carbon in solid viood products and carbon-offset through production of bioenergy crops. Furthermore, short rotation poplars and swiichgrass offer additional carbon sequestration and other environmental benefls such as soil erosion control, runoff abatement, and wildli!e habitat improvement. ;\imosplrt.ric cat-hot1 dioside ((;O?) hits increasrrl dramatically sit~ce thc hegirining o f the Inrfustrial Revolution its i i resiilt ~f httniati activities (Keeling and others 199.6, I-toughinn ant1 othcr-s 2001). I'he priniary c;riisrs rrf C 0 , i t~c l-c a i s ;ire i~i~r l d i~i d e f<)ssii ftiel burtiing, l i i~i s s r i g , atid ccriiclrt nianufirctit~-ing. .l'licsc activities are, i n tiit-n, tied ti, 111c expatiding ~vot-ld popiilation and a I-ising deoianil for cner