ANALYSISEx-ante assessment of the cost-effectiveness of public policies to sequester carbon in soils
Section snippets
Significance statement
Maintaining soil organic matter is critical to tackling climate change and controlling soil health. In this article, we study the effectiveness of a series of innovative Agri-Environmental Measures (AEM) that subsidize the use of compost in Guadeloupe, in the northeastern Caribbean. We combined estimates of the likelihood of farmers adopting agri-environmental measures, with biophysical simulations of the effects of adopting these measures on soil carbon sequestration. We find that measures
Statistical model to predict participation in AEM
In order to predict participation in AEM, we use a standard theoretical framework of choice modelling, based on the random utility theory (Marschak, 1960, Thurstone, 1927). We use the framework developed by Revelt and Train (1998), in which N respondents can choose from among J alternatives (here, AEMs for adding compost to the farmland) on T choice occasions. A farmer is assumed to choose an AEM if the net utility from choosing that alternative is greater than choosing either no AEM or any of
Surveys
The surveys were carried out over three months by two interviewers who received training on composting methods and on survey administration, including choice experiments specifically. The questionnaire was presented in paper form and consisted of three parts. The first part elicited the socio-economic profile of the farmers and included questions to establish an initial assessment of farmers’ practices, knowledge and perceptions of composting. The second part of the questionnaire contained the
Descriptive statistics
Descriptive statistics of the farms owned or managed by the survey respondents as well as their main socioeconomic characteristics are shown in Table 5. Only 9 percent of farmers have a poor perception of composting, 33 percent of farmers think that composting is beneficial, and 58 percent are not aware of the issue. Finally, 71 percent of farmers are aware of the existing European AEM scheme. With respect to socio-economic variables, the average age of farmers in the sample is 50 years and the
Farmers’ willingness-to-pay
Our results suggest that including non-cash incentive elements in agro-environmental schemes offering AEMs can contribute to the pursuit of ambitious environmental goals such as the 4 per 1000. Table 10 indeed shows that most of the proposed measures would achieve this objective quite easily. Computing the average value that respondents place on each non-cash attribute – something referred to as the willingness-to-pay (WTP) in the literature5
Conclusion
In this study, we sought to show that certain types of Agri-Environmental Measures (AEM) are likely to improve soil carbon at a lower cost. We designed an original framework coupling a mixed logit model to perform an ex-ante assessment of the adoption of AEM devoted to promote compost use, with a biophysical model describing soil carbon dynamics to establish the impact of AEM adoption on carbon sequestration in tropical soils. This approach was useful to assess a variety of scenarios combining
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment
Research funded by the French National Research Institute for Agriculture, Food and Environment (INRAE) and the French Environment and Energy Management Agency (ADEME), the Departmental Council of Guadeloupe (Grant No 41-000/211) and the Water Office of Guadeloupe (Grant No 41-000/405).
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