Discharging crop water is actually a waste of both expensive water and expensive fertilizers and at Priva they don't like that at all. That's why Kees van der Kruk is happy to inform us on the developments concerning the closure of the water cycle. What do we know and what is still unknown?
Water is of vital importance - it's a cliché but it is true. In recent years, also in horticulture water has attracted more attention. "In the Netherlands, that's partly thanks to the discharging rules, of course," says Kees. Ever since January 1st 2018 growers are obliged to remove at least 95% of the crop protection being used from their water before they can discharge, resulting in a lot of attention and many novelties being launched for water and irrigation systems. "We also saw this when the government intervened in the energy sector years earlier. As far as energy is concerned, the attention to water is still in its infancy, but awareness is beginning to grow."
However, there are still many topics that growers should think through when it comes to their water cycle. "Think about the amount of water you give and why you do that, think about the fertilization recipe that you follow. And how can you ensure that your water cycle is closed and that you no longer have to discharge water from the drain, or at least minimise the amount?" According to Kees, that is the ultimate goal. "Also from a financial point of view. Discharging is a waste of both expensive water and expensive fertilizers."
Closing the water cycle might sound simple but unfortunately, it is not. A water cycle is a complex technical system in which many different parameters play a role. "We are dealing with different recipes and fertilizers, chemistry, cultivation systems and substrates. In addition there's the quality of the input water, the way the water logistics is organised and of course the plant and its state itself. It all impacts the water cycle and if one thing is adjusted, the rest should follow. As a first step focus is on the accurate dosing of fertilizers. By finetuning the dosage as much as possible, more reuse is possible, because for example you have more control over sodium build-up in your water. Deviations in the drain make discharging inevitable, and that's what you're trying to prevent."
How does the plant feel about it?
At Priva, they've come a long way in this respect. "In the Netherlands, AB containers are often used. Dutch horticultural companies are quite far in controlling their water management. Growers regularly analyse the drain water and think about pre-treatment, the EC and pH levels. Based on this, we have a fairly complete picture of the situation. "
However, there is still a lot of research to be done. "There is in fact still a great deal unknown about the behaviour of plants in this respect. We can measure the difference between the input water and the drain water and draw the conclusion that the substances that are missing, are good for the plant, but that calculation is too simple. For example, how long does it take for the water to reach the plant, and has the plant's behaviour changed during this period? And what is the influence of other things, such as climate and evaporation?"
Taking samples, is that a solution? "Sure, but even over a short period the behavior of the plant can change. Much is still unknown about this. Now, for example, we are investigating the possibility of using a higher EC value. It seems that we can allow a higher EC than we do. For Priva, however, it matters also if we also know why this is the situation. When that knowledge is discovered, we share it with the large group. The essence remains that we not only want to correct, but also want to determine what happens from the start of the system. That is the future for us."
"Fortunately, Priva, as a control technology company, is strong in seeing systems through," Kees continues. "We look at the water complex and the cultivation as a whole. The most important thing about water systems in the future is to be aware of the entire cycle from the outset: what comes in, what do you use and what goes out? In order to identify and monitor this, we work together with partners in the chain such as Van der Ende, to fully map out the pump capacities, and with specialists from Revaho, Grodan, Yara and various consultants, for example. The strength lies in cleverly combining the knowledge of the links in this chain."
This is also very important for growers. "In the Netherlands, we are at the forefront of horticulture in any case, and this is also noticeable in irrigation and fertilisation. Many of the mistakes that are still being made internationally are hardly ever made in the Netherlands." He gives the example of working with water with a high bicarbonate level. "We sometimes see this abroad: if you don't know in advance, the unit will regulate a perfect pH, while the pH rises as soon as the water reaches the plant. In the Netherlands, mistakes like this hardly ever happen thanks to the high level of base knowledge."
Yet that is also a disadvantage somewhere. "Thanks to years of experience and the knowledge it has acquired, the level of Dutch greenhouse horticulture is very high. The added value of more advanced measurement and control technology, also in relation to water and fertilisers, is therefore sometimes extremely difficult to demonstrate, in contrast to greenhouse horticulture in other emerging countries, for example.
In the long term, however, the question is to what extent the plant's vitality/resistance could be increased. That is also why we continue to research the behaviour of the plant and constantly look for new technological possibilities to optimise our products. Thanks to the knowledge of how to close the water cycle, precision cultivation will continue to improve".