Your scepticism about a market-based approach to conservation in the Amazon is ill-founded (Nature 472, 5–6; 2011). It is based on a misrepresentation of the partnership in Brazil's Santarém region between US agricultural giant Cargill and environmental group The Nature Conservancy.

The aims of the Santarém partnership are explicitly environmental, not social as you claim. It was set up to reduce deforestation by enforcing Brazil's Forest Code (a federal law restricting the amount of deforestation) and the soya bean moratorium (a voluntary agreement by agribusiness not to source soya from land deforested after 2006).

The partnership monitors farmers' land-use practices in Santarém by satellite and by visits on the ground. Its contribution is crucial in the absence of a legal mechanism to enforce the soya moratorium and, given the limited government resources, the Forest Code.

Soya production in Santarém comprises less than 0.5% of the total production of the Legal Amazon (http://sidra.ibge.gov.br), yet this small region receives intense scrutiny from scientists and the media. Despite this, no evidence has emerged that the partnership has failed to deter deforestation. We must therefore consider what the environmental outcome would have been had The Nature Conservancy not intervened.