The benefits of CA range from supporting basic agricultural production and meeting food security needs in a sustainable manner, to supporting globally important terrestrial and soil-based biodiversity, culminating in carbon sequestration. This review of current thinking about these benefits suggests that the expansion of CA across many different agro-ecological zones makes good sense from a social perspective.
However, the financial profitability of CA is uncertain. Although there appears to be a small cost advantage over conventional practice in general terms, results are liable to fluctuate widely from site to site, with many studies showing CA as less profitable. There are also differences in analysing cases in developed versus developing countries, with tropical hilly examples from the latter group demonstrating distinct advantages for CA because of its more comprehensive approach and better agroclimatic conditions. In contrast, caution is warranted in temperate areas, as the CA approach promoted is less intensive and any cost advantage is likely to be insufficient for bringing about the levels of adoption and diffusion justified from a social perspective. In part, this situation occurs because farmers cannot capture the many national and global benefits from CA.
Given this divergence between private and social interests, interventions promoting more sustainable farming techniques are justifiable in a social sense, and at both the national and international levels. However, CA is not the only soil and water conservation technique that can generate the benefits cited above. Thus, it is necessary to situate CA within a broader range of alternatives to conventional farming practices. Encouragingly, CA is representative of a group of improved agronomic practices that are generally more profitable than competing soil and water conservation technologies that are more structural or purely vegetative in nature.
If CA-type approaches are preferable to the alternatives, then providing monetary compensation to induce adoption might seem an appropriate policy response. However, such an exercise is unlikely to bridge the gap between socially desirable levels of adoption and actual farmer behaviour on its own. Other factors affect adoption as well. For example, numerous such influences are statistically significant in models that attempt to explain actual adoption behaviour (as opposed to general discussions lacking empirical support). These other factors stem from different farmer management objectives, stewardship motives and fundamental barriers or constraints that inhibit a response to profit signals. In some cases, it is the collective rather than the private dimension that is critical to adoption success. There appears to be a correlation between higher levels of social capital and success in these situations. Thus, promoting CA must start with the identification of all factors that impeded adoption and not just a lack of financial net returns.
Policy has also been an important determinant in explaining past CA adoption or non-adoption. Policy stances have sometimes been weak and ineffective in promoting CA. Much of the successful diffusion of the technology has occurred because of support from private corporations, the formation and operation of farmers' groups and other non-governmental pathways. Moreover, conflicting policies have often operated at cross-purposes, encouraging and discouraging CA at the same time. Despite these shortfalls, examples of successful policy measures include green decoupling programmes in Europe and farmland stewardship programmes such as Landcare in Australia.
The above analysis contains implications for policy-makers. On the one hand, an assumption that CA will spread on its own in some desirable fashion is not appropriate. On the other hand, a uniform policy prescription to fit many locations is not realistic either, whether it consists of direct interventions or more indirect incentives stemming from research and development, or some mix of both. Designing successful policies to promote CA is likely to start with a thorough understanding of farm-level conditions. This understanding needs to include management objectives, attitudes to risk, willingness to make trade-offs between stewardship and profits. The next step is the careful design of location-sensitive programmes that draw on a range of policy tools. Flexibility is liable to be a key element in policy design to promote CA.
One area where policies of a more uniform nature might be useful is in the development of social capital and the promotion of the precursor conditions for collective action. For example, the social capital benefits of group extension approaches probably are under-appreciated. Given the demonstrated importance of farmers' groups and information dissemination in the successful diffusion of CA, efforts to strengthen the enabling conditions that foster these activities can pay large dividends.
In devising appropriate policies relating to CA and, more generally, sustainable agriculture, there is a need for improved policy analysis and information for decision making. Developing sustainability indicators that can more clearly show the benefits of CA over its alternatives is one step. Similar improvements are achievable at the economic-analysis level. For example, incorporating the depletion of natural capital in studies of conventional farming practices can help evidence the limitations of these techniques. Ultimately, a whole-farm systems approach may be the most appropriate basis for financial analyses of CA, as this can capture the full range of responses that farmers make when choosing to adopt a new technology such as CA. Moreover, it can incorporate the many options available to farmers in making such choices, something which is not possible in a simplistic comparison of conventional tillage and CA.