Monitoring of Flemish farms benefiting from derogation: design and organisation of a well-balanced and simplified monitoring network

In September 2015, the European Commission granted for the third time a derogation to the region of Flanders pursuant to Council Directive 91/676/EEC. This derogation provides the possibility to deviate from the use-standard of 170 kg nitrogen per hectare for animal manure in the period of 2015-2018. As for the two former derogations granted in 2007 and 2011, this derogation was subject to certain strict conditions. The condition which concerns this research is the obligation to set up a network of farms and to monitor the impact of derogation on nitrogen and phosphorus losses from soil and on water quality. The research started with the design and the set-up of the monitoring network. The network for the period of 2016-2018 is based on the network of the former period which in turn was based on the existing monitoring net for phreatic groundwater. During the former periods of monitoring however, no difference in impact on nitrogen losses from the soil and on water quality between derogation and non-derogation conditions could be assessed. Therefore the competent authority charged with monitoring, control and reporting decided to impose some additional conditions which had to be taken into account for the design of the new monitoring network. Unlike the parcel being the monitoring unit in the former monitoring networks, the farm had to be the monitoring unit in this monitoring network. Each farm is marked by a combination “crop-fertilisation strategy-soil type” at the start of the project, for instance “grassland under derogation conditions on sandy soil”, and the combination remains during the monitoring period (2016-2018). This was an important additional condition. Because of the number of possibilities for each part of the combination (6 derogation crops, 3 fertilisation strategies, 4 main soil types) a lot of combinations were possible, 72 to be correct. However the monitoring network was supposed to count 160 farms as requested by the authority. At each farm 3 parcels corresponding to the chosen combination will be monitored for nitrogen losses, being one of the conditions imposed by the authority. Since the comparison of the combinations should be statistically valuable which could not be realised considering 72 combinations at only 160 farms, a number of well-reasoned and argued simplifications were accomplished which resulted in the new well-balanced monitoring network.