Water management

Water management

In addition to light and heat, water is of the greatest importance for the good growth of tomatoes and, naturally, many other crops inside and outside a greenhouse. The good management of the available water for the crop is, therefore, very important. Water is also the resource in which we administer the fertilisers that the plant needs. Every plant has its own drip that makes the water available to the plants gradually. The water with the fertilisers is transported to the drips through the water system, the substrate area in the professional jargon.

Per hectare (10,000 m2), between 15,000 to 20,000 m3 of water (which is 15,000,000 to 20,000,000 litres) is needed for the crop on an annual basis. If the water supplied by the water irrigation system is not absorbed completely by the plant, part is stored in the substrate mats and, if they are saturated, the water will leak into the recirculation gutters. This means that the surplus water that is given is caught and is taken to the dirty water silo. The water will go through a UV filter from this silo to deal with vegetable and other contaminations. The purified recirculation water will then go to the clean water silo. This water can again be used for new irrigation in the greenhouse. What is great about this system is that all fertilisers are retained because of the recirculation.

Water is available to our company in three ways:

• Rainwater, all the rainwater that falls on the roofs of the greenhouses is collected in rainwater basins. They are usually created next to the greenhouses and the sizes vary from 1,000 m3 per hectare to 3,500 m3 per hectare.
• Reverse osmosis: groundwater is pumped and filtered with this process. The reason is mainly because our groundwater is saline. The clean fresh water is available for the crop and is pumped into the rainwater basin. The saline water (this is also referred to as brine) that remains after the osmosis process is taken back to the soil.
• Tap water: if there is insufficient rainwater (longer period of draught) and insufficient water is available from the osmosis process or reverse osmosis cannot take place, the company will use tap water. This water, of course, needs to be purchased.

Discharging

The company does not have to discharge, in principle, any water that is used for the crop because of the recirculation system. This is only necessary when the recirculation water is too saline because salt is not absorbed by the tomato plants. If the quantity of salt in the water becomes too high, this will be discharged by the company to the sewer system.