Reuse of drain water with a first-flush-system on strawberry trayfields drastically reduces the use of groundwater

In North-West Europe, short-day cultivars are mainly used in the production of strawberries. The plant production phase occurs in fall when temperatures decrease and the day length is gradually shortening. Timed input of nutrients in combination with sufficient irrigation ensures the production potential of these trayplants. Tray plants are propagated on a large, open field (trayfield) covered with an EPDM rubber that does not allow water to leach into the soil. By having this impenetrable barrier underneath the plants, all water will run-off to surface water bodies if not properly caught in adequate dimensioned storage silos. It is desirable to collect all water from those trayfields due to the high nutrient concentration and contamination of crop protection products. Furthermore a reduction in nutrients leaching to surface water bodies is desired. Unfortunately, trayfields are open fields and are therefore exposed to rainfall. To collect all run-off water huge amounts of storage capacity are needed to capture all the drain water which makes it economically not feasible. To determine which storage capacities are needed to adequately collect all nutrient-rich water, a first-flush model was constructed. This model combines an irrigation strategy, commonly used on trayfields, and precipitation data collected by KNMI over the past 60 years. A well dimensioned contaminated drain storage capacity is key in collecting nutrient rich drain water. When a contaminated drain storage of 100 m(3) ha(-1) was used, only 18.3% of modelled yearly precipitation data showed an overflow. Further increasing the contaminated drain storage to 200 m(3) ha(-1) reduced the risk of overflow even further. In only 61.7% of the modelled cases an overflow was predicted. Similar to the reduction of overflows during the propagation period, an increase in storage capacity from 50 to 100 m(3) ha(-1) led to a massive reduction in the use of groundwater as a supplementary water source. A well dimensioned first-flush-system can minimize the amount of overflows and keep qualitative irrigation water in a semi-closed system, this is especially helpful in dry summers when water is scarce.