摘要：Under the Kyoto protocol of the United Nations Framework Convention on Climate Change theUnited States is charged with reducing emissions of greenhouse gases to seven percent belowtheir 1990 levels by the period 2008-2012. These reductions could be met from many industriesincluding agriculture. In this paper, an economic simulation model is linked to the CENTURYecosystem model to quantify the economic efficiency of policies that might be used to sequestercarbon (C) in agricultural soils in the Northern Great Plains region. Model outputs are combinedto assess the costs of inducing changes in equilibrium levels of soil C through three types ofpolicies. The first is a CRP-style policy that provides producers with per-acre payments forconverting crop-land to permanent grass; the second is a policy that provides per-acre paymentsto all farmers that use continuous cropping, regardless of the land's cropping history; the third isa policy that provides per-acre payments for the use of continuous cropping only on land unitsthat had previously been in a crop/fallow rotation. The analysis shows that a CRP-style policy isfound to be an inefficient means to increase soil C resulting in costs that typically exceed$100 per MT (metric ton) of C. In contrast, payments to adopt continuous cropping were found toproduce increases in soil C for between $5 to $70/MT depending on the geographic area anddegree of targeting of the payments. The most efficient, lowest cost policy is achieved whenpayments are targeted to land that was previously in a crop/fallow rotation. In this range, soil Csequestration appears to be competitive with C sequestered from other sources.
