Last spring has been exceptionally dry. But exactly how dry has it been, and what is the best way for a grower to irrigate his crop? When you have the right equipment, you can measure exactly how dry the soil is and calculate the optimum amount of watering, as statistics provide certainty.
Growers do not have to be meteorologists to identify extreme drought or surplus precipitation. A good dose of common sense will go a long way, but this is still guesswork. It can be useful to analyse the exact soil moisture, as this makes it possible to irrigate much more accurately.
Tulip grower Maarten Breg of Boon & Breg from Andijk has experienced this at first hand. Over the past five years or so, he has been using measuring equipment to measure soil moisture.
“The big advantage is that this gives us insight into what is happening in the soil. You can put a spade or a stick into the ground, but that's not accurate.“
Boon & Breg decided to get its equipment from Dacom from Emmen. This company has gained a lot of experience of soil moisture measurements in crop farming. Boon & Breg has six measuring stations in total. They use one for each field. Each station consists of two parts: one post with a transmitter, and one post with sensors. The post with sensors is inserted about 60 centimetres into the ground. Every 10 centimetres, there are sensors that record the soil moisture. This post is connected to the transmitter on the other post with a cable. The transmitter also has a rain gauge. The transmitter is connected to the computer in the office.
A grower can see on a chart on the PC what the precipitation level was within a specific time frame. He can also see the depth reached by moisture within that time frame. It can be derived from the chart which layer has absorbed most moisture. That is the layer with the most densely rooted soil. If the roots cannot absorb any more water, it is clear from the chart that the deeper sensors have detected more moisture.
According to Breg, the increased insight into soil moisture has changed how we work. “It changes how you use your sprinklers. In the past you would feel the soil. Now you apply 20 millimetres of sprinkling, or 10 if the soil can't take any more. This can be easily assessed with the equipment. It turns out, for example, that it's better to irrigate 10 millimetres twice rather than 20 millimetres all in one go. If the crop does not absorb the moisture, you are irrigating for nothing. You'll only wash away the minerals. You should irrigate in such a way that no water is wasted as it goes down to lower levels.“
In addition to reading the amount of moisture, Breg can also read from the data how much moisture the crop can evaporate. Dacom's program adds that data and can produce a forecast. And that is exactly what Breg finds valuable.
“Because it doesn't really matter what the soil moisture is. What matters is what the crop can do with this.“
The system can be read anywhere in the world. Given that Boon & Breg are growing in Flevopolder in the Netherlands and in Chile, this is a major advantage. “We are far away, which makes it hard to get a feel for how the crop is doing. Now we can see what is happening.“
As the data is centrally stored, Dacom can view the data along with its customers. As Altjo Medema from Dacom explains, this is an important advantage. “In the beginning in particular, the grower will have questions about how a chart should be interpreted. I think that's absolutely fine. I prefer it when they ask a hundred times how it works; that's better than when they give up on it after a year because they don't know how it works“
“We can log in in Andijk and see how much rain has fallen in Flevopolder. That's useful if you want to go there. When this system shows that there has been a lot of rainfall, you know you can't do any work in the fields and might as well stay at home.“
Boon & Breg uses one station for each field of five to ten hectares. That is sufficient in principle, but Breg thinks there is room for further improvement. “A disadvantage is that there are many different products in bulb cultivation. These are all different in terms of water absorption and rooting. I would prefer to have five measuring points in a field.“ Medema does not rule out that multiple measuring sensors could work on the same transmitter in the future, as proposed by Breg. The technology for this already exists. A set with a sensor and transmitter costs 2200 euro. As Medema acknowledges, this is quite an investment. “But when I started eight years ago, a station still cost 3500 euro. The price has nearly halved because the components have become cheaper. This means the material is within reach for more businesses.“
Medema expects that the number of applications will further increase in the future. For example, the business is working on a simplified application of the computer program, so that it can also be used on a tablet or smartphone. The stations can now also be dispatched as a ready-made package, which means no installation costs are involved.
Breg finds it hard to estimate when the set will have paid for itself. “It's very hard to calculate this. What is most important is that you should start irrigating in time. This device will help you do so. You can recover the costs at the end of the season. If you start irrigating a few days late each time, you will have less yield at the end.“