Complementary instruments to EEC nitrogen policy in non-sensitive areas: A case study in Southern Spain

Current EC nitrogen legislation stipulates for the non-sensitive areas a preventive approach via the development of 'best management practices' (BMPs) within a context of voluntary implementation. Under existing technologies, the adoption of BMPs leads to economic losses. A crop simulation model (NTRM) and a mathematical mixed multi-objective programming model (NISE) are used to assess the effects of nitrogen price increase and drainage water reduction in inducing adoption of BMPs. The model shows that increasing nitrogen price cannot be used to stimulate farmers to adopt BMPs. On the other hand, imposing a tax on drainage water could lead to a reduction of up to 37% on the quantity of nitrogen leached with a decreased of only 1·5% in gross margin. However, above this level, drainage water is no longer a useful instrument to reduce and control nitrogen losses, and could lead to inefficient solutions in terms of gross margin and nitrates pollution.