Though the goal of all PES programs is the procurement of some sort of ecosystem service, the reasons why organizations or governments would incentivize the production of these services are diverse. For example, the world's largest and longest running PES program is the United States' Conservation Reserve Program,[3] which pays about $1.8 billion a year under 766,000 contracts with farmers and landowners to “rent” a total 34,700,000 acres (140,000 km2) of what it considers “environmentally-sensitive land.”[7] These farmers agree to plant “long-term, resource-conserving covers to improve water quality, control soil erosion and enhance habitats for waterfowl and wildlife.”[7] This program has existed in some form or another since the wake of the American Dust Bowl, when the federal government began paying farmers to avoid farming on poor quality, erodible land.[3]
In 1999, the Chinese central government announced an even more expensive project under its $43 billion Grain for Green program, by which it offers farmers grain in exchange for not clearing forested slopes for farming, thereby reducing erosion and saving the streams and rivers below from the associated deluge of sedimentation.[8] Notably, some sources cite the cost of the entire program at $95 billion.[3] Many less extensive nationally funded PES projects which bear resemblances to the American and Chinese land set-aside programs exist around the world, including programs in Canada, the EU, Japan and Switzerland.[8]