In recent weeks, J&A Flowers has tested the new CARA MET Soil sensor from SenseNL at De Lier. These sensors provide insight into the root zone of the plant. J&A Flowers is part of VannoVa, an alliance of chrysanthemum growers. Remco van Ruyven, who is responsible for cultivation at J&A Flowers, supervised the test. The CARA MET Soil is a new sensor that is suitable for use in the soil, says Bram Meulblok from SenseNL.
He explains: "The aim of the test was to see whether the data matches the grower's feeling in order to gain confidence in the sensors and to see whether the CARA MET Soil sensor can help J&A Flowers to gain insight into what is happening in the soil and thus optimize water policy.
Despite the fact that the sensors also measure temperature and EC, Remco van Ruyven is mainly interested in water content data. "Measuring EC and water content in chrysanthemum cultivation is difficult because it is grown in the soil, and the soil is tilled before each cultivation cycle. As a result, the composition of the soil around the sensor is always different for each sensor. Since it is possible to set the irrigation set point of each sensor ourselves after repositioning it in a new section, the values are reliable and can be compared with each other per section and cultivation cycle," says Bram.
The pilot was ultimately divided into three phases. In the first phase, two sensors were placed in three different sections: one at a depth of approximately 12 cm and the other at 25 cm. This setup aimed to assess how the effects of watering were reflected at varying soil depths.
In the second phase, the sensors were divided into two groups for two sections, two sensors at 12 cm deep and one at 25 cm. This was used to see to what extent the sensors were consistent in their measurement trends at the same depth.
In the second phase, the sensors were divided into two groups across two sections with two sensors placed at a depth of 12 cm and one at 25 cm. This arrangement aimed to evaluate the consistency of the sensors' measurement trends at the same depth.
The third phase, currently ongoing, involves comparing sensor measurements with soil sample to determine whether the observed physical properties of the soil align with the values of the sensors.
The first phase showed that it is not easy to measure the soil with sensors that have to be repositioned after milling. Since tilling creates variations in soil aeration and soil can settle over time, the sensors need to be calibrated after installation and the first watering. This process may need to be repeated if the soil has settled. In the second phase, two sensors were placed at a depth of 12 cm to closely monitor the settling process. Since the measurement graphs from the sensors at the same location and depth were consistent, deviate less than 3% from each other, and correspond with Remco's feelings; Remco is confident that in the future he can rely more on sensor data to control watering. With over 100 cultivation sections, this could save him a lot of work.
Remco mentioned that he prefers to minimize the frequency of watering because each session significantly increases air humidity levels. He wants to combine more sections for watering and potentially adjust the amount of water applied to each section.
"SenseNL has implemented an alert function in the web application, enabling the sensor to
notify when moisture levels fall below the minimum threshold and watering is required. A second lower limit could indicate when watering is allowed but not strictly necessary. This approach would allow J&A Flowers to combine sections more easily during watering sessions, reduce the number of watering cycles, and lower the relative humidity in the greenhouse," says Bram.
Fully automating watering, which is possible via the available link to the climate computer, is not an option Remco is currently considering. He does not want watering to happen automatically when work is still scheduled in a cultivation section.
Remco prefers to retain control over when watering occurs, but any assistance in determining which sections need watering or inspection will certainly save him time and effort.
For more information:
SenseNL
Ambachtsweg 41F
2641 KT Pijnacker, the Netherlands
Tel: +31 (0)85 876 89 09
www.caramet.com
J&A Flowers
Kreekrug 16
2678 PR De Lier, the Netherlands
[email protected]
www.jaflowers.nl