One common element in many voluntary and regulatory carbon markets to date has been the inclusion of emissions offsets that can be sold by entities outside of emission caps. A particularly low cost means of sequestering atmospheric carbon is reducing tillage of agricultural soils. A choice experiment is conducted with corn and soybean farmers in Indiana, USA to measure farmers' willingness to change tillage practices to supply carbon offsets by estimating their willingness to accept (WTA) payment related to different attributes of active and proposed carbon markets. This research is unique in its focus on the supply side of the market for environmental services, and contributes to the nascent literature on the valuation of the ‘means’ of achieving an improvement in environmental quality, rather than the environmental ‘end’ result of a proposed policy or market. Understanding farmers' preferences and willingness to adjust practices is vital to designing schemes that farmers will participate in so that global carbon abatement efforts can be achieved in the most cost-effective ways possible. We investigate attribute non-attendance (ANA) in our sample, estimate and compare WTA amongst adopters and non-adopters of no-till, and compare WTA with current carbon prices to evaluate the prospects for increased adoption.