The initial results of the study being undertaken by KWR show that the trial using reverse Level Controlled Drainage on the fields of dairy farmer Wilfried van Dijk is progressing successfully. Since November last year an Archimedean screw has been pumping purified wastewater from the neighbouring Bavaria brewery to the high, dry sand grounds of dairy farmer Wilfried van Dijk. The 2-year trial, which uses reverse Level Controlled Drainage, is aimed at showing whether the groundwater level can be sufficiently increased to benefit crops so the dairy farmer almost never needs to irrigation spray his fields again.
“That set-up seems to have succeeded,” concludes KWR researcher Ruud Bartholomeus. “But I have to add that we’ve not had a representative year and that makes interpreting the figures more difficult.” The fact is there were virtually no water shortages during 2016. “In June there was even an excessive amount of rainfall, as a result of which the water supply was stopped temporarily. At other moments we’ve been able to maintain a good water level.” In addition, it has not yet become clear whether the system can become contaminated or blocked during the long-term supply of waste water, in which a very small amount of contamination is always present. “And that’s a reason for us to continue the trial for a further year,” says Bartholomeus. Nonetheless, the groundwater level under the 9 hectare area of land has been raised by at least 1 metre, which is 40 centimetres more than the project partners had envisaged at the start of the trial.
Dairy farmer Van Dijk is happy with the results so far, though he can’t wait to modify the system so it works even better. “The land isn’t the same height everywhere, which means the lower-lying land receives sufficient water before the higher areas. We are currently looking into the possibilities of modifying the existing Level Controlled Drainage (LCD) using section valves.” Together with a consultant from the Southern Agricultural and Horticultural Organisation (ZLTO), Van Dijk is also investigating the possibilities of using purified wastewater from Bavaria to irrigation spray the areas that don’t receive sufficient water via the Level Controlled Drainage system during periods of drought. A water storage basin would have to be installed for this. Van Dijk would also like a larger area of land to be supplied using the Level Controlled Drainage system.
Source: ZLTO/Nieuwe Oogst (text and photograph: Marieke Verbiesen)