Department of Theoretical Production Ecology, Agricultural University, PO Box 430, 6700 AK Wageningen, The Netherlands

Background and objectives
Concern about negative side-effects of agricultural practices has caused objectives other than self-sufficiency to come to the forefront at European and national policy levels. In the Netherlands, progress in attaining targets of pesticide reduction set by the 1991 Multi-Year Crop Protection Plan currently seem to stagnate after initial successes. Lack of progress has been attributed to exhausting the range of simple adaptations, or in industrial environmental policy terms, 'end-of-pipe solutions'. Further improvement of crop protection will require fundamental changes in the production process and reconsideration of farming perspectives from a regional viewpoint. This paper addresses ways in which explorative crop protection research can generate such new perspectives by adopting a systems perspective. Two case studies are presented, one dealing with crop protection at the EU level [1], the other addressing flower bulb production at the farm level [2].

Materials and methods
The explorative approach used to derive options for farming systems and eco-regional development hinges on the distinction between value-driven objectives for agricultural production, and production techniques that can be described using scientific knowledge. In the EU case, study objectives were derived from policy statements and combined to four policy scenarios: free market and free trade, regional development, nature and landscape, environmental protection. Production techniques were formulated as crop rotations, characterised by input-output relations. A linear programming model was used to optimise allocation of crop rotations to land-units in the EU. This European study paved the way for more detailed analyses at lower integration levels. An example at farm level concerns flower bulb production in the Netherlands. Objectives of sustainable production were established in interaction with a group of farmers and environmentalists. Production techniques were defined as input-output relations for individual crops. A linear programming model was used to optimise crop sequences with respect to farm gross margin, subject to different restrictions on pesticide use and nitrogen surplus.

Results and conclusions
Results at the European scale revealed a large gap between current pesticide usage and the much lower levels necessary in any of the four scenarios. At the same time, highest and lowest values of pesticide input per hectare differed four-fold among scenarios, emphasizing that there is scope for a clear pesticide policy to be pursued at the EU level. In particular in north-western Europe, reduction in pesticide use can be brought about without loss of production.

Results at the farm scale demonstrated the trade-off between economic objectives, pesticide input and nitrogen surplus, and highlighted the potential of strategic choices to reduce pesticide input over tactical measures. Pesticide input at a particular level of farm gross margin was affected considerably more by choice of crop species and crop succession than by changes in in-season crop protection regime.

1. Netherlands Scientific Council for Government Policy, 1992. Ground for choices. Sdu uitgeverij, The Hague.
2. Rossing WAH, Jansma JE, De Ruijter FJ, Schans J, 1997. Eur. J. Plant Path. 103, 217-234.