Tomato company Lans in Maasdijk (Netherlands) cultivates various types of tomatoes on stone wool on 32 hectares in the Westland and 20 hectares in the Zeeland province. By far the largest part is illuminated. Only 10.6 hectares is still unlighted. The lighted cultivation is rotated earlier - in August and September - than the unlighted cultivation. In Nieuw Prinsenland in Dinteloord, a new 8 hectare greenhouse is under construction, where the first tomatoes will be planted at the end of this year. This is the first phase of an expansion, which in the future will be 34 hectares in total.
Keeping the water cycle closed
"The crop rotation should not be seen as something special, but simply as a part of the cultivation," says staff member Wilko Wisse. "During the entire cultivation, including the crop rotation, you have to ensure that the water cycle is closed and remains that way, so that residual water is not discharged onto the surface water."
The basis for closed cultivation is good starting water. For the tomato business this is rainwater, supplemented with reverse osmosis, so that the sodium content is minimal. "Our choice for the Poseidon is in part for the water purification, but mainly for the sodium removal to keep the water inside all year round. This is only possible if the sodium content remains low. And if you drain water into the sewer, you also throw away a value of 1.50 to 2.50 euros in fertilizers per cubic meter of water. That is a waste."
It is about awareness
The staff member quotes the Area-Oriented Approach project of the Delfland Water Board, where surface water in a specific greenhouse horticulture area is monitored 24/7 with mobile measuring equipment. "It's about awareness, so that you also handle the water flows well during the crop rotation, just like in this project. Through that awareness you also start to recognize things and do something about it when it is necessary. For example, the substrate slabs must be as dry as possible before they are transported from site. In the event that water does leak out, the gullies to the surface water in the yard must be capped. That leakage water must be collected and pumped to the waste water silo."
Preparing and discussing crop rotation
The crop rotation asks for the necessary preparations and a timely start. The last drain water should be used up as much as possible. Watertight waste containers must be ordered for the removal of crop and slabs. A sufficient buffer should be available to collect the cleaning water. Water that has been in contact with fertilizers, must not be discharged onto the surface water. This water must be collected and drained into the sewer, possibly after a purification step to remove the plant protection products.
Wisse: "Crop rotation is a hectic period, where a lot has to happen in a short time. Therefore, it is important to discuss matters with the employees well in advance. And it must not only be done quickly, but also safely."
Working together to reach solutions
The staff member would like to see growers and the Water Board working together to find solutions. "When an employee notices something, like a water leakage during the crop rotation, this must immediately be reported to a company manager in order to resolve it quickly. If there is a calamity, a grower must contact the Water Board. Many growers are hesitant to do that. The enforcers’ main interest is not to impose fines, but rather to act as advisors towards the growers. They are looking for a solution together, so that the right measures will be taken."
Source: Glastuinbouw Waterproof