Using appropriate amounts of water without doing sports fields anything short

Using sensors for remote monitoring of the moisture balance in sports fields

Sensor supplier ConnectedGreen, known from the soil moisture sensors for green projects, trees, planters, roof gardens and green walls, is now also active in the market for sports fields. Sales manager and owner René Voogt: ‘A shortage of volunteers, but also of water, that is the new reality. When the field usage is high, moisture sensors help to irrigate efficiently.’

Author: Karlijn Santi Raats – Tuesday June 30, 2020

For Sportservice ede, sensors have been installed in Ede by Van de Haar Groep. Krinkels did the same for sports fields in the municipality of Winsum, and since this month in Maastricht.

The ConnectedGreen-system consists of smart sensors, a Cloud environment and an app for field owners and contractors. All tasks are recorded in a log. Via a dasbhoard, both parties can check the status of all projects. If something needs to be done, the relevant stakeholders will receive a notification.

Neil Claessen, Krinkels

René Voogt: ‘Especially for sports fields without a built-in irrigation system, it is important to monitor the moisture balance. Some municipal sports grounds are still irrigated by the clubs, using reels and pumps. It’s costing a lot of time to get these at the right place. So it is really handy to know when you have to be where with that reel; that saves a lot of unnecessary transport movements. Because the system gives an early warning for too low moisture levels, the grass won’t turn yellow. And when there is no shortage, no water is wasted. The mosture data are visible for both the field managers as the users.’

Installation of the sensors

Krinkels had already installed sensors under the lawn of the Museum square in Amsterdam. In the area of sports fields, the company had gained expirience three months earlier, with the installation of ConnectedGreen sensor in sports fields in Winsum.

‘The sports fields should not suffer from an outdoor water-use restriction’

Planner and estimator Neil Claessen from Krinkels in Heerlen has recently installed four sensors in three fields in the municipality of Maastricht: in two of the twelve fields at multi-functional sporting ground Geusselt and in one of the eight fields at multi-functional sporting ground West. The two fields at sporting ground Geusselt both have one sensor installed, the field at sporting ground West has got two sensors installed. Because the project is a pilot, Krinkels and the municipality of Maastricht want to figure out if one sensor per field is sufficient, or if two are needed. The sensors have a length of 15 centimetres, which would mean that the measurements are just under the root zone of the grass. That is why they are placed horizontally at a depth of around 10 centimetres. Voogt: ‘The sensor should not measure too deep; it should measure at root depth.’The sensors are placed at a recognizable spot on the field which is representative for the moisture level in the entire field. That would normally be in or around the center circle. If a second sensor is placed, this would be placed around the goal, because of the intense usage of that area.

Ad Boer, Van de Haar Groep

Claessen shows where he has installed the sensors under the grass: in the same line as the irrigation pipes in the fields. That is easy for the orientation of the maintenance crew. ‘We always stay clear of the irrigation pipes during maintenance work. Placing the sensors in the same line prevents them from being hit and the locations can easily be added to the irrigation map.’

Soil moisture measurement

Ad Boer, planner with Van de Haar Groep, has three years of experience with the ConnectedGreen sensors. In 2017, an innovation-minded colleague shared a brochure with information about soil moisture sensors. When Van de Haar Groep was awarded a four-year contrect by Sportservice Ede for maintenance of their sports fields, the sensors were installed immediatel; six in total, spread over four fields. Both Van de Haar Groep and Sportservice Ede have access to the Cloud environment to view the soil moisture data via computer or app.

Krinkels Heerlen also shares the moisture data with their client. Claessen: ‘The field managers of the municipality of Maastricht have the ultimate responsibility for the fields, so they have to be able to look over our shoulder. Also, since it’s a pilot, these are the people who will have to judge if there is enough added value in using these sensor data.’

Earlier, Van de Haar had also installed sensors at sports club Candia ’66, but these have already been removed. Club volunteers are very frequently present on the sports ground and they water regularly. Boer explains: ‘The volunteers over there are the ears and the eyes of the club; remote monitoring is not necessary for them. We offer the sensors as additional service to our clients and then evaluate for which clubs or sports ground they offer real added value.’

Interpretation of data

The ideal soil moisture percentage lies between 5 and 15 percent. These percentages can easily be viewed in the app. This way, Boer monitors all fields on a daily basis. Van de Haar Groep shares the soil moisture data with Sportservice Ede. And they forward the message to the clubs, if a field is showing to be too wet or too dry. There is one field that consistently shows abnormal values: ‘I think this is due to a sub-optimal place of the sensor; we will move it to another place. That can be caused by a hard underground layer or a wrong setting of water pressure or reach of the irrigation system.

Preferably, Boer wants the sensors to be a bit shorter, so they don’t measure as deep as they do now. ‘When the sensor is placed too deep, it measures below the root zone. That means there should be a customization of the sensor geometry for sports fields, That is something for the future.’

René Voogt, ConnectedGreen

Take action at the right moment

Claessen, of Krinkels: ‘More and more sports clubs have issues with shortage of volunteers, so it is important to work efficiently. Besides that, water should be used more efficiently too. The past years we have seen outdoor water-use restrictions in many places. The grass should not suffer from these challenges. The sensors measure the exact need for moisture of the grass plant, so in principle there is no shortage.

In Maastricht, both sports grounds are equipped with an automated irrigation system and watering is overseen by employees of the municipality. Claessen still thinks the sensors provide added value. ‘At these sports grounds, the usage of the fields is quite high and they are also rented out to host events. The pressure to provide good fields on which many people can set foot, is high. Watering is essential for a strong field. The sensors and app can be of help for field managers; remote monitoring helps them saving time and kilometres and watering is being done efficiently.’