Crop tour Onions - week 26
Despite drought, the onions are growing like crazy
Now that we are in the period with the longest days of the year, the onions get a signal to start forming bulbs. And yes, we cannot escape it: it is dry in the Netherlands. Plots that regularly get an artificial shower have good growth, but in other places the onion crop is hungry for water.
After the second weekend in a row in which we had to deal with summer temperatures, and where the next 30 degrees are already on the forecast, the onion crop is extracting an awful lot of moisture at this stage. That is not bad at all for growth, temperature in combination with regular (artificial) showers (provided that those temperatures remain within limits). But in places where irrigation is not possible, it is starting to become urgent.
Big difference between being able to irrigate and not being able to irrigate
It is well known that it is dry in the Netherlands. Klaasjan Boer from Kortgene in Zeeland knows this too. He reports that it is now really becoming bone dry in Zeeland. This is also reflected in the onion crop, he says. "The leaf tips are starting to turn a bit yellow, and the crop is also not growing well in this way. Not all potato plots have their land covered either." For David de Wit from Lepelstraat (North Brabant), the drought can also come to an end. He is now irrigating for the sixth time (!).
More irrigation bans
Due to the drought, more irrigation bans are being introduced, for example in the Rijn en IJssel Water Board. In this area, which concerns 200.000 hectares, it is prohibited from 25 June to extract water from rivers, ditches and streams in the Achterhoek, Liemers and parts of the Veluwe and Overijssel. The groundwater level is lower than normal, reports the water board. The precipitation deficit in this area has now increased to 173 millimeters, more than in the dry year of 2018.
Klaasjan can talk about the precipitation deficit; since sowing, his onions have had about 50 millimeters of water, and they have to make do with that for the time being. "In such a year, the difference in soil type is also very visible. Beautiful, orderly soil, the crops simply grow much further with this drought," says Klaasjan.
Using drip irrigation
The declaration of a ban on irrigation was a reason for René Haaijer from Veelerveen in Groningen to start using drip irrigation. He indicates that it is no longer self-evident that you can use surface water at any time. Not only René, but also Reinder Hogenhout from Kimswerd in Friesland and Peter Holster from Marknesse (Flevoland) use drip irrigation. For Peter it is the first time that he uses drip irrigation. "It is quite a process and the question is whether the system suits you. It takes a lot of work and you have to carefully check every round to make sure that there are no holes in the hoses". René agrees: "It is a lot of work every year, but if it yields something in the end, it is worth it to me". Reinder is very resolute about the use of drip irrigation: "Less labour, less fuel and above all no more problems with surrounding seed potato plots."
With drip irrigation, Reinder applies about 10 to 12 millimeters daily, without stress, he says. The water calmly reaches the right place, without compacting the soil. It does take longer, he indicates, but according to Reinder it is about watering at the right time. For him, that was also one of the reasons to start with drip irrigation.
René and Peter also use fertigation in this way. "The crop has a huge foliage package, but I notice that the leaves remain so remarkably light in colour. When I look at my other onion plot, where I do not use drip irrigation, it is much darker in colour," Peter observes. He indicates that because the nitrogen and potassium are applied in small quantities via fertigation, the nutrients are released more slowly, which allows the crop to grow in a dosed manner. "The crop is just starting to bulb, and the big advantage of fertigation is that I can continue to apply nitrogen until the end of the season. In this way, the crop grows a little further, I think."
Drought causes lower mildew pressure
For Klaasjan, it was time again on Tuesday 24 June to protect his onions against mildew due to the drizzly conditions. His last spraying was already eleven days ago. He indicates that he has not had any problems with dew-wet mornings recently. He also uses an advisory program, which he follows closely. "The program indicated that it was not necessary recently. If you have such a program, you have to dare to trust it a little. And with my own observations in the field, I have not found it necessary before." Peter Holster, on the other hand, has his spraying schedule set at six days. Earlier this week he had a shower of 5 millimeters and he thought it was time to protect his onions again. In addition to protecting the onions against mildew, Klaasjan also uses a lot of biostimulants. "It is the only thing we can do to keep the crop vital and more resilient, because we cannot irrigate."
For Hubert Linders from Nederweert in Limburg, last weekend was the second time that he irrigated his onions. His onions are looking great, he says. Especially when he makes the connection with last year. "I only sowed my onions on May 10th last year. Around this time there was one pipe on it, now the first onions are already 3,5 centimetres thick." René Haaijer also thinks that his onions have recovered considerably, after some significant precipitation fell in the north of the country recently. After René had previously suffered from hail damage, he says that it has recovered reasonably well as the crop continued to grow. "The pipes with leaf loss are still visible and that means that the onions will be somewhat more sensitive to bacterial invasion."
Jan Willem Veldman
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