Is it appropriate to support the farmers for adopting conservation agriculture? Economic and environmental impact assessment

摘要

Conservation agriculture (CA) in the last decades has been spread in several parts of the world, especially in South and North America and Australia. In Italy, however, its adoption is often restrained by the risk to have a reduction in crop production in the early years of transition from conventional (CT) to CA. To quantify sufficient financial support to promote no-tillage and CA, a mini-review about main effects of CA was conducted. The effect on crop yield, soil fertility - especially as it is influenced by the chemical, physical and microbiological factors - on soil compaction, the economic balance of the farm and the cost of equipment for direct seeding, the influence of environment on soil erosion, water retention, emissions of greenhouse gases, and carbon sequestration are briefly treated. The paper reports findings from national and international scientific literature and some results from long-term experiments conducted in Southern Italy. The main conclusions are about the reduction of yield in the first years of transition from CT to CA (from -5 to -10%), an improvement of soil fertility (soil organic carbon increases in the upper layers), reduction of management cost (less machinery operations), improvement of soil C sequestration (in specific conditions), a reduction of greenhouse gases emission and soil erosion risk. The paper provides the scientific basis in order to justify and quantify the amount to be paid to the farmers who decide to adopt the model of CA, oriented to protect the agro-ecosystem and to promote the principle of subsidiarity. Finally, a proposal of public subsidy in cash and for machinery purchase has been described.