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Pay extra attention for water on dry days:

"Water first, the rest can wait"

Stefan Bakker, product manager for Revaho, says it is important that the water supply is in order during dry and warm periods. "Due to low precipitation, the water layer is thin and pollutes more quickly. This creates problems with extra filter rinsing water, clogged filters and drippers. This is always at the cost of the cultivation turnover," says the product manager.

"The problem is that a small water supply becomes polluted very quickly. Due to a low water level the organic or mechanical pollution increases. This increases the amount of rinsing water, as the filters need to be rinsed more. The loss of valuable water for rinsing isn't great in times of water shortage. On the long term there can be clogs in the system due to dirt. The killing layer is also a feeding ground for organic pollution. This increases the disease pressure, which adds chemicals to the water to resolve this."

Algae bloom
The cause of the pollution is in a low water level, which thickens the water and the soil at the bottom causes pollution. As the water layer is thin, the sun can penetrate to the bottom and warm the water up considerably. This increases the organic disease pressure of fungi, bacteria and viruses. 

Bakker: "If the created conditions are favourable for an algae explosion, contagion with or the latent presence of algae from surface water, for example, can lead to an algae bloom. Algae don't form a threat to the cultivation, but can cause blockages in filters and drippers."

Killing layer
Due to climate change the intensity of rain showers is increasing. Short, heavy showers that cause a lot of precipitation in a short time, will be increasingly common. In a dry period the result of this is that a large amount of water suddenly ends up in a thin layer of water with bottom particles. Due to the disturbing of this muck this layer is pushed through the water storage. "This quickly causes problems with pollution, especially if the intake is close to a suction pipe. It takes days for the killing layer to sink again, but in the meantime water is still needed. Sometimes we can't get it and growers ask whether the screen filter can be removed, as it quickly clogs up due to the pollution. But this isn't the solution," according to the product manager.

Large and full water storage
To play into the changes with fierce showers with large amounts of rain water, his advice is to make the rain water storage as large as possible and keep it as full as possible. If a basin or silo is big enough for sufficient storage, it won't deplete as quickly. "Make sure that your water storage is filled in dry and warm periods."

Some growers use surface water or osmosis water as an addition to rain water. The product manager: "Use ditch water in the early spring, when the quality is still reasonably good, and be sparse with rain water until it is really needed. Use other water sources, such as spring water or piping water early enough in the season."

Osmosis water
"Turn on the osmosis machine in April, for instance. You are running the risk of your basin or silo overflowing into the ditch, But the risk of not having enough water in dry periods and your drippers becoming clogged is much higher and costs more turnover," says Bakker.

If they turn it on early, a grower can still opt to only run the machine in the cheaper energy hours. Electricity is 30 to 40% of the exploitation costs. A large capacity of the RO installation is therefore recommended. 

Publication date: 7/3/2017



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