How to Meet the EC-Nitrate Directive in Dutch Vegetable Growing?

To improve nutrient management in Dutch practice, in 2002 a project was started with 33 commercial farms including 9 vegetable farms. Farm-specific fertilization strategies were developed and tested. Nitrogen (N) and phosphorous balances were calculated and soil mineral N content in autumn and nitrate concentration in the ground water were measured. The project was supported by model farm calculations focusing on development of cost-effective sets of measures to improve nutrient management. Results show that on many participating vegetable farms a fertilizer strategy consisting of conventional measures (following recommendations, type and amount of manure, N side dress systems, catch crops) is not sufficient to meet the EC Nitrate directive. Model farm calculations show that extra, less conventional measures, like removal of crop residues or less intensive cropping systems are required. However, this strongly increases costs