Scenario analysis using the Daisy model to assess and mitigate nitrate leaching from complex agro-environmental settings in Denmark.

Nitrate (N) leaching from intensively managed cropping systems is of environmental concern and it varies at local scale. To evaluate the performance of agricultural practices at this scale, there is a need to develop comprehensive assessments of N leaching and the N leaching reduction potential of mitigation measures. A model-based analysis was performed to (i) estimate N leaching from Danish cropping systems, representing 20 crop rotations, 3 soil types, 2 climates and 3-4 levels of manure (slurry)-to-fertilizer ratios, but with same available N (according to regulatory N fertilization norms), and (ii) appraise mitigation potential of on-farm measures (i.e. catch crops, early sowing of winter cereals) to reduce N leaching. The analysis was performed using a process-based agro-environmental model (Daisy). Simulated average N leaching over 24 years ranged from 16 to 85 kg N/ha/y for different crop rotations. Rotations with a higher proportion of spring crops were more prone to leaching than rotations having a higher proportion of winter cereals and semi-perennial grass-clover leys. N leaching decreased with increasing soil clay content under all conditions. The effect of two climates (different regions, mainly differing in precipitation) on N leaching was generally similar, with slight variation across rotations. Supplying a part of the available N as manure-N resulted in similar N leaching as mineral fertilizer N alone during the simulation period. Among the mitigation measures, both undersown and autumn sown catch crops were effective. Effectiveness of measures also depended on their place and frequency of occurrence in a rotation. Adopting catch crops during the most leaching-prone years and with higher frequency were effective choices. This analysis provided essential data-driven knowledge on N leaching risk, and potential of leaching reduction options. These results can serve as a supplementary guiding-tool for farmers to plan management practices, and for legislators to design farm-specific regulatory measures.

Are independent agricultural advisors more oriented towards recommending reduced pesticide use than supplier-affiliated advisors?

This paper explores whether agricultural advisors employed by chemical companies or agricultural companies selling pesticides (supplier-affiliated advisors) are more likely to recommend more intensive use of pesticides than advisors employed by companies without an economic interest in selling pesticides (independent advisors). We further test whether potential differences in advice are caused by differences in advisors' perceived demands for advice from farmers, different environmental risk perceptions about pesticide use or different weighing of the purposes of pesticide use. The analysis is based on a survey administered to the whole population of 540 advisors in Denmark; we received 227 valid responses. The main finding is that pesticide advice differs across company type. We find that supplier-affiliated advisors are less likely to recommend lower doses - scoring on average 3.9 on a scale from 1 (never) to 5 (always). Independent advisors employed at Danish Agricultural Advisory Services score an average of 4.3. The difference is statistically significant. The analysis does not offer strong support for the different causal mediators we examined. Advisors across company type tend to weigh different objectives equally; tend to agree on environmental risk perception of using pesticides; and differ only slightly on perceived farmer demand. One possible conclusion, therefore, is that explanation is as simply that differences in economic incentives produce different recommendations between advisory companies. Policy implications of the findings are that the European Union should consider addressing this difference more directly when regulating the use of pesticides in European agriculture through e.g. the Sustainable Use of Pesticides Directive (Directive, 2009/128/EC). More differentiation in the approaches for informing different types of advisors might be needed. Moreover, our results point towards the need for knowledge about whether advisors in other countries than Denmark tend to believe that approved pesticides are innocuous to the environment because such perceptions might hamper initiatives to reduce the doses of approved pesticides.