Prefer often a little water, than sometimes a lot

“When a growth site dries out, it is difficult to get it wet again.

It is dry in the Netherlands, so dry that the soil can become water-repellent. René Voogt, who helps greenkeepers monitor the water level of their plants through data interpretation using ConnectedGreen’s technology, explains what is happening.

Author: Karlijn Klei

Voogt has been observing the drought in the Netherlands for some time through the data from the sensors that the company has distributed across the country. “Despite the relatively wet winter,” Voogt explains, “many growth sites never fully recovered from last year’s drought.”


“The soil contains pores,” Voogt explains. “The size of these pores can vary, from large pores in sand to very small pores in clay. This is useful because it allows the soil to supply trees and plants with moisture and oxygen. However, when the soil dries out, the pores fill up with air. The soil becomes so dry that it becomes hydrophobic, or water-repellent. This is a very common phenomenon with long-lasting adverse effects.”

To recover from the drying out, the soil needs not only water but also time. Normally, this recovery occurs during the winter when there is less evaporation and more rain compared to the preceding months. “However, this winter was not wet enough to fully replenish the growth sites after last year’s dry period,” Voogt explains. “Especially in places with a sandy subsoil, the hanging and ground water has disappeared or sunk deeper due to the drought.” René compares the dried-out soil to a sponge. “If you throw a bone-dry sponge into a bucket of water, it doesn’t absorb the water immediately. It regains its water-absorbing function only after soaking for a while.”

“Drought makes the soil hydrophobic, or water-repellent.”


If you are dealing with hydrophobic soil, it is important to give it smaller amounts of water more frequently rather than a large amount at once. “If you pour a large amount of water on it at once, it simply washes away,” Voogt explains. This leaching occurs either through the surface, such as rainwater flowing over paved streets, or directly through the growth site towards the groundwater. However, the water level has become so low in many places due to the drought that the roots can no longer reach it.

“We need to give water more frequently in smaller amounts instead of occasionally giving a lot,” Voogt emphasizes once again. This wisdom is not new, of course, but with the drought of recent years, it is more important than ever. “In practice, people often drive a tractor to a tree and fill the watering ring once or twice. Unfortunately, only 10 to 20 percent of the water remains in the hydrophobic growth site – and that is a waste, of course.” Not only of water and labor, but also of the nutrients and salts in the soil, as they are washed away with the water.

The degree of leaching can be visualized with the data collected and analyzed by Voogt using ConnectedGreen. Voogt says, “The steeper the peak on the moisture graph, the more leaching is occurring. This can be observed with a large water application to a dried-out growth site: the moisture content rises very quickly but also decreases almost as rapidly. When you perform smaller, more frequent water applications, the peak is less steep: water is added more slowly but also stays in the growth site better. By carefully observing this, it is possible to find the optimal amount of water to maintain the average moisture percentage. In practice, this can save up to 70 percent of the water volume. In a medium-sized municipality, that can quickly save several hundred thousand liters per season.


The essence of the story is: if you let the growth location dry out, it becomes very difficult to moisten it again. Voogt says, “So it is important not only to water correctly but also to properly construct growth locations and planting areas.” Here, the reuse of rainwater plays an important role. The drought we are facing is alternating with another extreme: short but very heavy downpours. By using structures such as water buffers or crates around and under the planting areas, you achieve two goals at once. Voogt explains, “On one hand, you capture peak water that may otherwise cause waterlogging. Hydrophobic soil behaves more or less like pavement. By capturing the water, you prevent waterlogging and have water available for use when needed. This creates micro-systems that are independent of whether groundwater is available or not.”

Unfortunately, such structures cannot be installed just anywhere. In those cases, according to Voogt, it is crucial to maintain everything very well through monitoring. “You need to intervene before the soil dries out. If it has already dried out, then you have to provide water in a cautious manner. It is really time to reconsider watering practices and the construction of growth locations,” concludes Voogt. “I believe the growth location of the future will be a combination of innovations like those we have seen at the Gouden Gieter.”

“The growth location of the future is a combination of innovations like those we have seen at the Gouden Gieter.”

Bullying the Roots

Watering is a complex issue. Although you need to keep an eye on the water needs of your trees and plants, you shouldn’t “spoil” them, as Voogt explains. “If you serve plants their every wish, they can become ‘lazy.’ This means that a tree or plant no longer needs to develop its roots further to reach water, and therefore doesn’t do so.” If you then skip watering once, the tree is in trouble. Due to its underdeveloped or less developed root system, it cannot access the ground or subsurface water. “Nursery growers are aware of this. Trees on nurseries are watered in a way that encourages root development. We call it ‘bullying,'” says Voogt. “You need to tease the roots a little so that they develop properly.”

Source: Stad+Groen

Municipalities Veldhoven and The Hague achieve significant savings with Connected Green

Founder René Voogt himself is well aware that sensors and the Connected Green platform yield many benefits in multiple ways. However, he is also pleasantly surprised by the magnitude of the savings. Michel Romeijn from the municipality of The Hague and Ron Berben from the municipality of Veldhoven share their experiences. “A saving of approximately 1,200,000 liters of water per year, we did not expect that.”

Author: Heidi Peters

Earlier this year, Stad + Groen published an article about the moisture monitoring system of Connected Green. Since then, several municipalities, including Veldhoven and The Hague, have started using it. Ron Berben, an independent green advisor hired by the municipality of Veldhoven, enjoys experimenting and conducting research. Therefore, when the municipality invested in six sensors with the accompanying software based on his recommendation, he saw an opportunity to assess the added value of Connected Green. Berben compared the costs of watering – both the water itself and the labor – for the seventy trees monitored by the sensors with the costs for trees cared for in the traditional way. Berben states, “There is a saying: measurement is knowledge. This certainly applies to moisture sensors. We often think we know a lot through experience and professional knowledge, but reality can be challenging. With current technologies, we can do much more than we realize, so we should delve into it and make more use of it.”

“We often think we know a lot through experience and professional knowledge, but reality can be challenging.”

Significant Savings

In Veldhoven, around 300 trees were knocked down due to storm damage last year. The 70 trees replanted afterward are now being cared for based on the data from the sensors. In total, 840 trees have been planted in the municipality of Veldhoven over the past year. Berben says, “The investment in the sensors and the associated subscription quickly pays off. After three months, I calculated the difference. If we had cared for all 840 trees based on the moisture sensors, we would have saved €20,000 in water, labor, and material costs in three months. I am genuinely surprised. You don’t waste water, but you also don’t give too little, so the tree is optimally cared for. And there is no need for extra trips to check the status of the tree and the soil. That is another internal saving not included in the amount. It also allows for monitoring the execution. The moisture sensors show a peak when water is given.”

From six to thirteen

Berben: ‘We started in the municipality of Veldhoven with six sensors. It was also a trial for Veldhoven, intended to convince colleagues where necessary. This indeed proved necessary, and we succeeded. Afterwards, we ordered seven more sensors. Working with sensors has an impact on your daily work. Using a soil auger to determine the condition of the ground is no longer necessary as often. There are far fewer wasted hours, and we work much more efficiently. You can remotely read the data and condition of the soil and then determine the next steps. For young trees, it is crucial to water them at the right time. Giving water too late can stress the tree. This hinders growth, causing the tree to take longer to continue growing without care. All these factors are why I am very positive about the use of Connected Green’s sensors.’

Sensors for drainage

Terraspect consulting firm, working on a project in Hendrik-Ido-Ambacht, also approached Berben for a unique situation. Construction is taking place around a pear berceau, planted in 1922. The berceau is located on a field, and now houses are being built around it. Due to its cultural-historical importance, the municipality wants to preserve the berceau. However, the construction has an impact on the groundwater level, especially here in the lower-lying west of the country. Berben: ‘Drainage has been installed so that the pear trees do not have their roots in the water. That’s nice, but for the preservation of the trees, we need to know two things: does the drainage work, and do the trees receive enough water from above? In early June, we placed eleven sensors, with a combination of one sensor at 90 cm and one at 60 cm in four locations. The sensor at 90 cm should indicate that the soil is wet, and the one at 60 cm should indicate that the soil remains moist but not wet. As long as the sensors indicate that, we know that the drainage is working. Although the sensors are easily movable, that is not the intention for these. They have a permanent monitoring function. So, you can use the sensors for something like this as well. Very convenient.’

The Hague already has sensors in planters, and in the spring of 2020, these will be supplemented with twenty sensors for trees. For the most accurate advice, the soil in which the sensors are placed should closely resemble one of the calibrated types in the app. The soil mixture for trees in The Hague differs slightly from the ten available soil types in Connected Green. Therefore, the municipality sent a soil sample to Connected Green, which was then sent to the laboratory for calibration and added to the app. Romeijn says, “We started with twenty plant and tree sensors to get an idea. What does the program do exactly, how does it work, what do the graphs say? The sensors are placed in locations with varying conditions, such as near a ditch, in the city, and on a slope where the soil is often drier. In our municipality, we have to care for 1,500 new trees annually. The results are surprising and provide clarity for the long term in some places as well. For example, you can see that trees near a ditch eventually provide enough moisture themselves. If you monitor that for a while, you can conclude that the sensor can be removed from there.”

No more fixed watering rounds

For the team that had been accustomed to the fixed watering rounds for years, it took some getting used to. Romeijn explains, “There were concerns that there would be less work for the team itself, but that’s not the case. We save on hiring and the consumption of surface water. After four months of working with Connected Green, I noticed significant savings considering the weather conditions of this season. Last year, we were driving around with five tractors; now we have an average of three, so two fewer. I attribute one of them to more efficient watering thanks to Connected Green. Additionally, I implemented a digitized water route, which allows us to drive more efficiently. That also saves one tractor. Calculate it: hiring a tractor full-time for twenty weeks costs a pretty penny. In addition, there is less diesel emissions, and we pump around 1,200,000 liters less water. We have 1,600 locations in the city where we visit for ten water rounds per year. That’s a total of 16,000 locations annually. By using sensors, we save between 50 and 100 liters per location. Taking an average saving of 75 liters per location, that amounts to approximately 1,200,000 liters less water that we pump.”

Accountability for community funds

Romeijn continues: “I also appreciate that I can use the information from the sensors to show, based on facts and evidence, how much money I have spent and how much water I have consumed and why. It’s possible that we will have a much hotter and drier summer next year, and therefore we will need more water. With this information, you can also justify the need for it in those circumstances. Furthermore, as a municipality, we want the new trees to thrive because replacing a tree that doesn’t survive due to insufficient water also incurs costs. This way of working is truly the future. We are significantly expanding the number of sensors in the coming period.”

“With this information, you can substantiate the necessity of watering.”

“Cruyffian simplicity”

“Reduced water consumption and healthier, better trees are the objectives of the dozens of municipalities that are already using our system,” says René Voogt, the founder of Connected Green. “That’s why they come to us. Measuring the conditions of green areas with sensors is not new, but it is often a very technical story. And that’s where our program sets us apart. It contains a database with information about the specific needs of the 2400 most commonly used perennial plants and trees, such as their water and light requirements and frost sensitivity. Just as one tree is not the same as another, the same applies to different types of soil. Sandy soil requires a different amount of water compared to, for example, loam or clay. That’s why we have calibrated the eleven most commonly used soil types, including soil from The Hague. The combination of the soil and the plant provides the optimal watering advice. By the way, we are sensor-independent and can connect sensors from all brands to our management system.”

Voogt concludes: “We see in our customer base where it’s dry. Municipalities in the south and east of the country are more affected by water scarcity and make more use of the app. The app displays a graph and provides a notification when it’s necessary to water. It’s truly designed with Cruyffian simplicity. More insight, fewer costs, that’s what it’s all about.”

Source: Stad+Groen

The digital platform Werkwijzer is enriched with water supply data from Connected Green.

This spring, the full integration of the sensors and associated application of Connected Green and the Werkwijzer platform will take place at three launching customers. The goal of this collaboration is to create an improved workflow management for their customers. The integration is made possible through a recently developed coupling module that enables data exchange between the systems. What does all of this exactly entail?

Author: Jeroen Poldermans

“You can say: I drove to a tree and I watered it, or you can say: I drove to a tree and I watered it because the sensor indicated that it was necessary. That is a completely different justification for the deployment of people and resources for your client,” said René Voogt from Connected Green. This simple example perfectly illustrates the essence of the integration of both systems. Real-time information about input from the field that generates tasks to feed the workflow. The best of both worlds!

“I drove to a tree and I gave water because the sensor indicated that it was necessary.”

The establishment of the collaboration Connected Green and Werkwijzer have a mutual customer: Snoek Puur Groen. They asked if the data from the water supply sensors could be integrated into Werkwijzer. This question reached Pieter Verloop from Werkwijzer. Verloop said, “We took this question seriously because our platform is precisely intended to unlock data and thus better manage work processes. I then contacted René (Voogt), and from there things started rolling. During our explorations, the idea arose to expand and future-proof the Snoek Puur Groen project. That was the basis for the integration of both systems.” To combine the data and optimize the workflow, a coupling module had to be built to merge the data from the systems. After its release, Werkwijzer became the first platform with a connection to Connected Green.

Connected Green moisture sensors

Connected Green was founded in 2017 by René Voogt with the mission of making the world greener through smart technology. The moisture regulation system of Connected Green consists of smart sensors, a cloud environment, and an app for both clients and contractors. The sensors measure the soil moisture level. The sensor data is sent to a platform, which includes a logbook and a dashboard that functions as a traffic light system. The distinguishing feature of Connected Green lies in the stored data about the 2,400 most common plants and trees in urban green spaces, as well as information about various standardized soil types. Soil types that are not in the database are further examined in a laboratory and added afterward. One of the clients using this system is the municipality of The Hague. After four months of working with sensors, it resulted in savings of approximately 1.2 million liters of water, as well as fuel and manpower.

Strengthening each other’s strengths

The integration is particularly interesting for large landscaping companies, green space providers, and municipalities. With the collaboration and integration of both systems, the partners respond to the demand for more data-driven workflows. Verloop said, “The integration is a classic case of synergy. A clear strengthening of our systems. Generating tasks based on sensor data is definitely an added value that we can offer to our clients.”

Voogt: “The domain knowledge that we incorporate into Connected Green is highly relevant for people in the field. Our app provides an overview of a specific field situation, and based on that, you can take action. Werkwijzer offers the possibility to display the interpreted data (whether trees and plants need water or not) and the resulting tasks (e.g., watering) on a map, enriching that information with, for example, a logbook (who provided water, when, and how much). Acting on an alert already happens in our app, but the management processes are not as intelligently defined as in Werkwijzer. They are specialists in work processes, and we specialize in sensors. In that respect, little will change. Everyone does what they’re good at. In other words, ‘stick to your own trade!'”

Examining the Benefits

The major advantages of working with Connected Green’s sensors and app include significant savings in terms of water usage, labor costs, project visits, and replacement planting. For instance, using moisture sensors in the municipality of Veldhoven resulted in savings of €20,000 in water, labor, and material costs over a period of three months. The key benefits of using Werkwijzer are real-time insight and control over the work activities, increased efficiency, the ability to build a historical record through log files, and generating tasks based on field input. Integrating both systems creates a perfect link between outdoor and indoor management. Imagine sending an invoice as a landscape provider for providing water. Such an invoice becomes more transparent when the watering actions are based on tasks generated and supported by the sensors. This way, the financial accountability leads to fewer disputes. By understanding the water requirements, you can optimize the allocation of personnel and resources.

The accumulated historical data supports the calculations made and any subsequent invoicing. For the workers, the major advantage is having an interactive work chart and being able to see their location based on GPS. Their activities and reports are immediately visible on the GIS map. Transparency, effectiveness, and focus improve both indoor and outdoor tasks, leading to better plant growth—let’s not forget that this is the ultimate goal.

Integration of systems in practice

What will users inside and outside now notice about this integration? The Werkwijzer platform consists of modules called building blocks. Connected Green will become an optional building block of Werkwijzer that can be activated by clients. When that’s the case, users inside, such as managers and planners, will be able to use the Connected Green dashboard, which functions like a traffic light system. If the background is red, the system indicates a water shortage. If it’s orange, a specific project requires attention, and if it’s green, the water level is adequate.

Field employees will notice little difference due to the software merger. They will report the task of “watering” in the system and see the real-time effects on their GIS map. Therefore, user-friendliness will not be compromised.

Digital map platform of Werkwijzer

Werkwijzer is a relatively young and ambitious company specializing in digital work process management. The eponymous digital platform is based on GIS, a geographic information system. The platform provides all necessary information for both clients and contractors. The Werkwijzer application is primarily developed for executing parties, focusing on work execution and providing the correct field information for clients and management.

The future

At the time this edition of Stad + Groen is delivered, efforts are underway to roll out the integration. Voogt states, “Different people will likely work with different apps. For example, setting the soil types and monitoring the trees will be done in the Connected Green app. The tasks resulting from these actions will be monitored in Werkwijzer. In the future, certain tasks will also be combined, such as watering and emptying trash cans when you’re already at that location.” Verloop is ambitious about future plans, saying, “Currently, thanks to the integration, we use moisture sensors, but I don’t rule out the integration of data from other sensors (light/temperature) from Connected Green in the future. This way, we both become more complete data partners for our clients.”

“Scheduling personnel is important when the drought and chaos strike again.”

Kicking off in Emmen

Being one with nature is what Snoek Puur Groen stands for. This large landscaping company from Grou (with a branch in Emmen) aims to let garden and outdoor space owners fully enjoy the scents, colors, and sounds that nature offers. Owner Douwe Snoek is always on the lookout for innovations in green maintenance and has a preference for sustainable, preferably circular products. In line with their sustainability goals, Snoek uses Connected Green’s sensors to provide water only when necessary. They use Werkwijzer to monitor and control work processes. Snoek Puur Groen wanted to integrate Connected Green’s data into Werkwijzer. Simone Arends, a tree and climate-adaptive advisor, explains, “Thanks to Werkwijzer, our clients can follow the execution of work processes, which increases transparency. For example, they can review the maintenance history. This is ideal for a large client like the municipality of Emmen, with more than twenty locations, as it helps maintain an overview. We have already installed Connected Green sensors for various clients. For our work for the municipality of Emmen, we will fully utilize the integration of the sensors and Connected Green’s app in Werkwijzer. The interface is user-friendly. The sensors color an area red, orange, or green; it’s that simple. It makes our work clear and easier. For instance, we can also see where we don’t need to go (green), which is important for us when scheduling personnel during the chaos of drought.”

Implementation in Weert

Attender Groen is a company with a diversity of talents and, as a regionally involved green company, is part of the Vebego Groenbedrijven in the Netherlands. They operate with over 300 colleagues from three locations: Meerssen, Hoensbroek, and Nederweert. Their clients include municipalities, housing corporations, healthcare institutions, and businesses. Attender Groen is implementing the integration of Connected Green into Werkwijzer for the municipality of Weert.

Regional Manager Tim Schreurs from Attender Groen says, “We find it important to be able to monitor our complete assignment in one system. The integration of multiple different parties in Werkwijzer makes this possible. Having different systems means having to monitor multiple software applications. Through integration, this monitoring is simplified, and we have all the data for analysis in one place. We expect to achieve significant water savings in the municipality of Weert through the addition of Connected Green sensors. By also focusing more on the values generated by the sensors, we can use our equipment more effectively. Ultimately, reducing water usage and using equipment more efficiently will also lead to a reduction in CO2 emissions.”

Source: Stad+Groen

Connected Green: Sensor Management is a Specialty

The use of sensors for measuring soil moisture has proven to be a great success. Now the focus is on better interpreting the data to achieve even greater “gains.” Connected Green has fully equipped its platform with state-of-the-art technology and is currently training special sensor managers who make tree care more efficient. Several green space providers are already working with a sensor manager. René Voogt (Connected Green), Jan Willem de Groot (Pius Floris Tree Care), and Elsemiek van de Kamp (Ter Riele) delve into the tips and tricks of sensor management.

Author: Emiel te Walvaart

Connected Green is a platform for monitoring green spaces, utilizing sensors connected to the Internet of Things. The effectiveness of the sensors is beyond question. However, by better assessing the value of the data from these sensors, even more can be achieved from the system. René Voogt (Connected Green) explains, “We configure the sensors in human language and provide an easily understandable representation of their status. In other words, we add domain knowledge to the sensors. That’s the added value. We ensure that the right information reaches the right person at the right time. We do this for many green space providers and municipalities. Currently, we have over 2,000 sensors in use in the Benelux region, serving 120 organizations that use our platform.”

A Separate Field of Expertise

Currently, there are organizations and municipalities that use tens to hundreds of sensors. The Connected Green system is designed to be flexible, allowing sensors to be moved between different projects. In such cases, effective sensor management becomes increasingly important. “Which sensors do we have? Where are they located exactly? Managing these sensors has essentially become a separate field of expertise. In the first few years, our focus was primarily on convincing people how the system works and its benefits. But now, we need to inform users about the possibilities of moving sensors from one project to another. To facilitate this effectively, you need to engage in sensor management. It’s actually a specialized field, and we’re assisting more and more customers in this regard. That’s why we developed the sensor management training, which we first provided at Pius Floris, as they have around two hundred Connected Green sensors in total.”

Depending on the agreed-upon post-care period for projects, users can relocate sensors to different locations after a certain period. The entire system is designed to support this. “At the beginning of 2020, we announced new steps for our system, such as integration, management, and calibration. These developments have now been fully integrated into our package, including a coupling and user management module. We can see that customers are now ready to delve into sensor and user management. As the number of sensors and stakeholders increases, users want to share information and know where each sensor is located.”

This is Only the Beginning

According to Voogt, we are just at the beginning. “Connected Green is growing rapidly. Most companies start with a limited number of sensors to test the concept. This year, larger clients will begin deploying sensors on a large scale. The demand for green spaces in public areas is increasing. There is a need for local recreation due to lockdowns. People also want their children to grow up in cleaner air, and there is a rising trend of nature-inclusive construction and urban farming. This means that greenery is being incorporated around buildings, but it’s not as natural as in a forest. Trees on rooftops or balconies, or green walls, need proper monitoring. If you neglect that, the tree will suffer.”

Voogt also wants to contribute to knowledge sharing for the green sector with Connected Green. The company is a member of NL Greenlabel and is actively seeking other partners. ‘Our platform is sensor-independent, so we can connect any sensor. The more sensor data, the better. Sensor suppliers need to be platform-independent, and platform suppliers need to be sensor-independent.’

Voogt is not sitting idle and is looking towards the future. ‘I expect that every company in our sector will be working with a sensor or data manager. I also think that forecasts will become more important in the future. When you can align actions with what the sensors report, the predictive capability becomes greater. For example, we have a reporting module as well as an analysis and prediction module in the pipeline. It will soon become indispensable and very interesting because it will indicate how much water you should give a tree. This will be based on past data combined with expectations.’

Better coordination

One of the companies using the Connected Green platform is Pius Floris Boomverzorging from Veenendaal, for over three years now. They currently have around two hundred soil moisture sensors placed in various locations in the Netherlands and Belgium. The tree care company aims to make the most out of the platform to better serve their customers. As a result, four employees were recently trained as sensor managers. René Voogt from Connected Green provided the participants with the necessary knowledge and skills to work with soil moisture sensors, enabling them to better manage projects and analyze sensor data.

‘Tree planting is crucial for us,’ says Jan Willem de Groot, franchise manager at Pius Floris. ‘If you don’t provide proper aftercare, your entire investment is essentially wasted. Watering often goes wrong, either too much or too little. With the help of the Connected Green platform, we can better control this process. Before we started using it, there was only one option to monitor a tree: making a physical visit. For example, we had a schedule where we watered once a week. With the sensors, we can now adjust the watering based on the actual situation and needs,’ De Groot states.

He emphasizes the importance of interpreting sensor data. ‘Naturally, we all want a device that tells us exactly what to do. However, you still need to use your common sense, even when using sensors. You can place a sensor in the ground, but you still need to understand how soil moisture management works. This can be a pitfall for some people.’

Close coordination

Currently, Pius Floris has sensors placed in around 45 projects, with an average of three sensors per project in the Netherlands and Belgium. The sensors are regularly moved to different projects, and the sensor managers oversee this process. They manage the system on the backend, ensuring the correct settings and parameters. This increases usability within a large organization, according to De Groot. ‘You can’t expect every employee to immediately know how to work with the sensors. That’s why we have trained these specialists.’

Initially, De Groot himself was responsible for sensor management. However, due to the large number of sensors in use, Pius Floris decided to assign several employees to handle this task. This way, communication lines remain short within the various companies under Pius Floris. The sensor managers can handle most matters, only seeking assistance from De Groot or Voogt from Connected Green for complex issues. This way, knowledge is distributed more effectively to local projects.

De Groot also sees various advantages of Connected Green. ‘This way, you can demonstrate to the client with measurement values that you have provided water. Moreover, you prevent giving water too early or too late and can plan the watering much better. Additionally, you can monitor the soil moisture trend more easily, which allows you to save water. If you don’t have to water once during the season, it saves a lot. You can also give water to the tree at an important moment, so that it takes root. However, in my experience, you should not rely blindly on the sensors because the quality of the tree is essential. You also need to physically assess the tree. All in all, Connected Green is a very effective addition to tree aftercare.’

An important focal point is the knowledge of soil moisture management. De Groot says, ‘Invest in it to understand what you can do with the sensor data. If you don’t, you’ll go astray. It’s truly a knowledge tool. So far, we have learned a lot from the process. Anyone considering using Connected Green should take note of that. You want to avoid someone claiming that the sensor doesn’t work. That’s not fair. If you start using the product without substantive knowledge, it can lead to frustrations and misunderstandings. That’s the pitfall.’

Remote monitoring

Another partner of Connected Green is the landscaping and green maintenance company Ter Riele B.V. The first sensors were installed in April last year. ‘One of the reasons was that 2018 and 2019 were very dry years, and we wanted to better manage the watering. It’s quite a distance if you have to drive from Klarenbeek to Winterswijk with a tractor. During those dry periods, you were giving a lot of water, but you could never really verify if it was the right amount at the right time. It also plays a role that we work on various types of soil, such as dry sandy soil or wet clay. By monitoring remotely, you can work more accurately and be more efficient with water,’ explains Elsemiek van de Kamp, calculator/work preparer at Ter Riele.

Around fifty sensors were installed by Ter Riele to streamline the watering on a green project along the A1, from Deventer to Azelo. The Connected Green platform was also used in a construction project in Amersfoort. For example, a sensor was placed near a newly planted large beech tree measuring 40/45 cm. ‘In recent years, it has been observed that the beech tree dries out quickly, and it is located on dry sandy soil. We also incorporated Lumido into the soil during planting to retain moisture properly and reduce the risk of loss. By providing timely watering and proper planting, we ensure that this beech tree takes root. We can now monitor the watering well with the sensor.’

Van de Kamp learned a lot about the ins and outs of Connected Green when René Voogt assisted in setting up fifty sensors for the A1 project at Ter Riele. ‘Various questions arose. What is the right location for the sensor? Which types of trees can you use it for? How many sensors do you place for different numbers of trees? Are there different soil conditions? What soil improvements have been made? And so you have to choose the least or most ideal situation, depending on your requirements. You also need to provide the GPS coordinates accurately when placing a sensor so that you can find it again. You should not forget that when you move the sensor to another project.’

Furthermore, Connected Green is useful for providing the client with insight into a project. “For example, you have to deal with the specification requirement for tree replacement. If a tree doesn’t take root, you can always use the sensor to demonstrate that you provided it with sufficient water. If it has rained, for instance, you can postpone the watering. This way, you can be accountable to the client.”

Knowledge of moisture management

Van de Kamp is happy to list some advantages of Connected Green. “Because you have a better understanding of the soil condition, you can now water much more efficiently. You can also share the measurement data with the client.” However, the system doesn’t function optimally without good management. “The preparation of a project with sensors is crucial. You need to know where to place a sensor. You also need to be aware of the species included in a planting plan and their water requirements. You need broad knowledge of trees and their moisture management.”

Van de Kamp advises new users to take the time to calibrate Connected Green and the sensors because the system is highly cost-effective. “If instead of watering ten times a year, you only need to water seven times, then you’ve already recouped the cost of the sensor.” Van de Kamp collaborates with project implementers to maximize the effectiveness of Connected Green. She also uses the Jewel route app in combination with the sensors to drive as efficiently as possible for watering.

Ter Riele will increasingly rely on Connected Green in the future. “That doesn’t mean we’ll use it for a project involving five plants. We will use it, however, when we’re managing a project with seventy trees in the near future. Then we’ll install four or five sensors. Whether or not we use it depends on the specific project.”

All in all, Connected Green is an excellent system, but according to Van de Kamp, it’s crucial to have good sensor management in place. “Because if you work with incomplete data, it’s better not to use the program.”

Why is sensor management important?

When it comes to measuring soil moisture, there are many different parameters to consider. It starts with placing the sensors in the right location, depth, and soil type. It’s also necessary to consider the connection with KPN’s LoRa network, proper app settings, sensor configuration in projects, and location on the map. Additionally, you need to connect the appropriate users to receive information and assign the correct permissions. And don’t forget that you have to integrate the app to use the data in other systems. All of these aspects together constitute sensor management. “The user should be able to manage Connected Green themselves and rely on us as little as possible,” says Voogt. “Companies are collecting more and more data and need to process and make it available. That’s why there’s an increasing number of data managers in our industry. For that reason, we have launched the sensor management training. You can complete it in half a day.”

Source: Stad+Groen

Smart moisture sensors will optimize data-driven fleet management.

Curious Inc. is a company specializing in the mobility and logistics market with data and telematics solutions. They develop software to support sustainable and efficient fleet management. On December 8th, they entered into a collaboration with ConnectedGreen, a specialist in sensor technology. The goal of the partnership is to perfect data-driven work processes, such as municipal green and gray maintenance, to achieve ultimate transparency and efficiency.

Author: Jeroen Poldermans

“You don’t want green and gray to each have their own sensors, applications, and workflow support. What we want is to have one integrated environment for route optimization, and green and gray management to be part of that.” Those “we” are René Voogt (founder/owner of ConnectedGreen) and Hans Schaap (founder/owner of Curious Inc.). Data-driven work is the future, so this collaboration may be the turnkey solution that municipalities and green companies have been looking for. What does this sustainable partnership entail?

“Green maintenance is not an isolated work process for a municipality.”

More than just a collaboration

The agreement is more than just a collaboration. It means the full integration of both systems to optimize data-driven workflow support. On one hand, Curious Inc.’s asset management software is enhanced with the data, domain knowledge, and customer knowledge of ConnectedGreen. On the other hand, users of the ConnectedGreen platform are connected to efficient asset and fleet management applications. It’s an ideal match because organizations that work with the ConnectedGreen platform generally manage a fleet, and Curious Inc. develops applications for more efficient vehicle usage and route optimization. The best of both worlds.

“Green maintenance is not an isolated work process for a municipality but is usually combined with other tasks, such as emptying trash cans. Curious Inc. has already developed an application for gray maintenance, which is being used in several cities. The integration with sensor technology that drives green maintenance is a logical and possibly crucial expansion of both portfolios. The collaboration is not only sustainable but also serves a common sustainable goal, as the enhanced expertise results in significant fuel savings.

Enschede municipality as a pilot

Curious Inc. comprises three business initiatives with their respective applications. One of them is Grybb, which takes care of gray management planning for the Enschede municipality down to the last detail. “Do you also happen to manage trees alongside the gray assets?” With this question from the Enschede municipality in mind, Schaap sought a company dealing with green matters. “That’s how I got in touch with René Voogt, and the first collaboration started as a pilot project in Enschede,” says Schaap. Enschede had already purchased sensors from ConnectedGreen, and Schaap and his team facilitated their implementation and integration with the asset management software. “This pilot was a great success, and we’re now planning expansions. That’s when we started thinking about a follow-up, which has now been officially sealed with a contract,” adds Voogt.

The importance of sensor technology

The moisture sensors measure the moisture levels at root level and provide information on whether young trees and/or plants need water. This information is collected in the ConnectedGreen platform and serves as the basis for:

  • More efficient routing, resulting in savings on fuel, water, personnel, and equipment.
  • Transparency in work processes. Invoicing becomes more transparent thanks to the data input.
  • Reduction in losses of green assets.
  • Accountability for municipal tax funds to the citizens.

We had a wet summer in 2021. Were the moisture sensors still useful?

“That is a logical question, and the answer is: yes! Even in wet conditions, the moisture sensors are valuable. Our intuition tells us that watering is unnecessary, and the sensors confirm that, resulting in savings. Especially this year, with all the rainfall, a significant amount of money was saved due to the consistent information. For a municipality, it is important to remove any uncertainties regarding the necessity of irrigation. With a shortage of personnel, you don’t want people to spend time checking whether a tree actually needs water or to provide water when it’s not necessary,” explains Voogt. Schaap adds, “A colleague mentioned that he was able to reduce tree losses with the sensors. Tree losses incur significant costs due to the failure of the tree to establish, as well as the expenses associated with the history of such a tree. These costs have increased considerably in recent years due to the growing volume, labor costs, and logistics involved in tree management.

Curious Inc.: From Student Startup to Niche Market Leader

During his technical studies, Hans Schaap focused on sensor technology to measure a wide range of variables, from air temperature to humidity. It was during this period that he developed an interest in the concept of the Internet of Things (IoT). The IoT consists of physical objects, such as cars, household appliances, and wearables, that are connected to the internet and can transmit data online. After completing his studies, he founded his startup company, GreenStar Logistics, which applied IoT in the field of mobility and logistics. This led to the idea of developing data-driven workflow solutions for the mobility market. One of these sustainable mobility concepts was the Driving Behavior Coach. The first application created by GreenStar Logistics was called Dation, focusing on driving schools. As a result, they became the market leader in this niche in the Netherlands and Belgium. Their second successful application is YesHugo, which provides support for thousands of vehicles through trip registration, track-and-trace, and vehicle movements. The third application is the previously mentioned asset management application, Grybb. Eventually, GreenStar Logistics grew into Curious Inc.

“Sustainability has been the core idea behind all our applications from the beginning.”

Sustainability as the Core Idea

“Sustainability has been the core idea behind all our applications from the beginning,” Schaap continues. “The Driving Behavior Coach module, for example, was specifically designed to save fuel. Another example is the Mobility Battle we organized in collaboration with the Province of Overijssel under the YesHugo banner. Companies and organizations from Overijssel received a year of driving behavior coaching and then competed against each other. Participants had to save as much fuel as possible and avoid rush hour traffic. They could earn points by accelerating and braking less forcefully, traveling outside peak hours, or not using their cars at all. I can provide more examples, but the important point is that our philosophy of sustainability and our expertise in telematics and mobility align seamlessly with the vision and core business of our partner, ConnectedGreen. I believe that we are currently the only ones who can offer the entire spectrum of data-driven workflow solutions for both gray and green management.”

In The Hague, some routes of green companies have been shortened by 25% thanks to the data from the sensors.

The success story of smart sensors

ConnectedGreen was founded in 2017 by René Voogt with a mission to make the world greener through smart technology. In 2018, he showcased his moisture sensors for the first time at the Public Space Trade Fair. Since then, both working with sensors and data-driven work have taken off. The ConnectedGreen platform consists of smart moisture sensors, a cloud environment, and an app for both clients and contractors. The sensors measure the soil moisture level. The sensor data is collected in a digital platform equipped with a logbook and a dashboard using a traffic light system symbolism. The differentiating power of ConnectedGreen lies in the stored data about the 2400 most common plants and trees in urban green spaces, as well as information about various standardized soil types. Soil types not present in the database are further examined in a laboratory and added. One of the clients using this system is the municipality of The Hague, where working with sensors resulted in savings of approximately 1.2 million liters of water, fuel, and man-hours after four months.

Common area of expertise

Data-driven work is gaining momentum because clients want maximum transparency and efficiency in their workflows. “I believe that the integration of our systems is important because we want to apply data-driven work not only to green management,” says Voogt. “Next to a tree, there might be a trash can. Curious Inc. offers propositions for municipal services like ’emptying trash cans.’ They, like us, work with sensors that drive data-driven work processes, and our domain knowledge of urban green spaces is essential to them. Both of us are involved in smart city applications, and our areas of expertise have a significant overlap. Over 120 organizations are now using the ConnectedGreen platform, and this collaboration is a logical next step to offer data-driven work on a broader scale.”

“The collaboration is a logical next step to offer data-driven work on a broader scale.”

Future plans

The signatures have been signed, and as a result, Curious Inc. acquires the brand, software, and staff of ConnectedGreen, while ConnectedGreen will continue to exist as a brand. René Voogt will remain involved until Curious Inc. has everything running smoothly. For the relationships of both ConnectedGreen and Curious Inc., nothing will change except for the fact that they will have more possibilities. “With the expansion of our portfolio, we aim to better support municipalities that want to set a good example in sustainable solutions. Therefore, I invite the readers of Stad + Groen to exchange thoughts and ideas with us,” concludes Schaap.

Source: Stad+Groen

Will you join? Together, we can turn lawns and grass fields into blooming havens for bees and butterflies.

The Bee Foundation aims to transform dull grass mats into bee oases full of flowers with the campaign “Don’t mow in May!” It’s a paradise for insects. The more flowers there are, the more nectar there is, which means more happy bees and butterflies.

Author: Malon Gerrits

Leave the lawnmower untouched for a month

That’s the call from The Bee Foundation, Flora of the Netherlands, and the Stone Break Foundation. In Belgium and the United Kingdom, they have been practicing this for longer. In England, it has been proven that if you don’t mow your lawn for a month in May, you can attract up to ten times more bees. Bees don’t eat grass, of course, but they need the flowers and plants. With fewer insects like butterflies and bees in nature, it’s up to us to lend them a helping hand. This assistance is particularly crucial in May.

Why May?

During the winter months, honey bees huddle together in their hives by the thousands. In spring, most bees begin their adult lives. When the food supply starts flowing abundantly, the queen lays more and more eggs, and the brood nest expands rapidly. However, for the food supply to get going, it needs a kickstart… That’s why it’s good for the dandelion to stay a little longer.

Did you know that the queen can lay up to 2,000 eggs per day, which is more than her own body weight?

During the summer months, everything is in bloom, and there are many places where insects can find their food. But in May, when bees come out of their “winter sleep,” there is little available. That’s why we need to lend a hand to the insects. Your lawn contains more plants than just grass. They only bloom when you let your lawn (or part of it) bloom.

So join us, leave your lawnmower untouched, and create a feast for these cheerful buzzers!

Blooming dandelions are a delight for bees and other insects. And when dandelions bloom, the maple trees also come into bloom. In a single tree, hundreds of thousands of small flowers bloom. That’s why blooming trees are equally important for insects.

Spring is always an exciting period. The changing atmospheric conditions (warmth, cold, rain) greatly influence whether or not the first important flowers for insects bloom. Whether it’s very wet or very dry sometimes has significant consequences for the nectar release from the flowers. Therefore, it’s essential to monitor soil moisture.

With a soil moisture sensor, you can remotely monitor the water supply of your tree, container, flower bed, lawn, roof garden, and facade garden. Measuring soil moisture provides an indication of when your trees and plants need to be watered again. This way, your trees and plants can thrive in the optimal conditions, grow and bloom abundantly, and produce nectar. Additionally, it prolongs the lifespan of your favorite green companions.

The Hague, the city known for its beautiful dunes, is also famous for its stunning parks and estates. The streets, avenues, and natural areas in The Hague are green thanks to its trees and plants. Nature in the city is vulnerable. The municipality does various things to protect, care for, and maintain nature in the city. Not only do trees and plants receive regular pruning, but they are also regularly watered. Especially new plantings are well taken care of because a city with diverse plants and animals is a healthy and attractive city. Read how the municipality protects and strengthens nature in The Hague’s city center with smart sensors and an online dashboard.

Author: Malon Gerrits

A city full of color

In addition to the greenery of different trees, many flower pots add a cheerful mix of colors to the city. From petunia-like plants and geraniums to white carnations, Indian reed, and much more. You can find them in various pots distributed throughout the city. These pots provide a solution to the space shortage in the city center. Each season, you’ll find different flowers and plants there, making the city center look beautifully vibrant all year round.

Dealing with drought (and downpours)

The trees and plants are well maintained and cared for throughout the year. Fixed routes help the caretakers provide water to the flowers, trees, and plants. Especially during the heat, these green water consumers appreciate an extra sip. However, water shortages and different heat plans make it more challenging. This needs to change, become smarter, and more efficient. Marco van Tol, Coordinator of the Green Center, also thinks so. Endless rounds with water tanks, not knowing whether the trees and plants are too dry or too wet, and simply watering because it’s the “task” for the day are a thing of the past. Soil moisture sensors from ConnectedGreen allow for smarter and more efficient work. But above all, it’s more sustainable!

More peace, more time, and at the same time, lower costs

About four years ago, Marco started monitoring soil moisture with wireless sensors. A pilot with ten sensors quickly yielded a lot of interesting data. The pilot was so successful that the soil moisture sensors became indispensable in The Hague’s green management just one year later. All flower pots in the city center are equipped with at least one sensor per location. In places with multiple flower pots, soil moisture is monitored using two sensors: one in a pot in the shade and the other in a pot in the sun. This way, Marco creates a reference point for action.

More time

By responding to the data, as a green manager, you can save a tremendous amount of time and water. For example, the flower pots in the sun can be watered while the pots in the shade can be skipped in a round.

“By better scheduling the routes based on this data, we were able to save two days per round quite quickly.” – Marco van Tol, Coordinator of the Green Center

“Three years ago, we started monitoring the flower pots in the city center. In the first year, it already saved us two days per round compared to previous years. When you calculate this in terms of labor, it’s a significant savings. It also meant that we could include more flower pots in one route.”

“We received more and more requests for flower pots, and at some point, you reach a limit with your planning and such, and you start searching in the margins. The sensors have really contributed to this. We were able to organize routes more efficiently.”

Less water

“When the gardeners start their routes, they check the app. If a flower pot outside the regular round urgently needs water, it can easily be included in the route. Because when the flower pots in the regular rounds still have 40% water, they require less water than before. Previously, we used to give each flower pot around 80 to 100 liters of water. The tank releases 7 liters of water per minute. So every liter of water you don’t have to spend on such a flower pot saves a significant amount of time.”

Apart from saving a lot of time, monitoring also saves a lot of water. “Take a period like the past month, when it’s very hot and dry. Previously, the gardeners used to think that all flower pots needed water in such heat. Now, with the sensors, the gardeners can see exactly where they need to water and where they don’t. This gives the gardeners much more peace of mind.”

More peace of mind

“Our drivers log into the ConnectedGreen app and see exactly how things are going on their route. Thanks to this monitoring, work can be done more efficiently, and more work can be accomplished in the same amount of time. Nonetheless, the boys and girls in the field feel more relaxed, creating a sense of calm within the team. Additionally, we avoid surprises, such as a sudden failure of an entire planting location.”

Increased satisfaction

“Monitoring puts you in a process that keeps getting better and better. In addition to more efficient route planning, the flower pots started looking better and more well-maintained. The rounds could be done more frequently, which also meant less failure. Ultimately, this resulted in fewer complaints from citizens, so they are satisfied.”

“Nationally, there is still a lot of surface water that can be saved through monitoring.” – Marco van Tol, Green Center Coordinator

Currently, Marco’s department is working with a total of 85 sensors. He is so enthusiastic that he recommends the sensors to other nurseries as well. He believes there is still a lot to save in terms of water supply for them. Even if the top layer seems dry, it could very well be moist underneath. You can only be sure of that by measuring it. Additionally, water pumps often run on diesel. So when you give less water, less fuel is needed. It’s a win-win situation.

New developments

In addition to technological advancements, the flower pots in The Hague are also undergoing significant developments. The polyester pots with small reservoirs are being replaced by flower pots made of recycled plastic. These pots have a double wall, which creates stagnant air inside, resulting in a constant soil temperature and less evaporation. The reservoir with overflow provides a good buffer. This makes the flower pots much more sustainable, and this can also be proven with the sensors.

“With the sensors, we can effectively measure the differences in flower pot types. In the first year, it turned out that the new flower pots needed significantly less water than the polyester ones. It’s possible that this is partly due to the choice of plants, which is why I’m reevaluating this year as well. However, this time I’m testing with different crops to see the difference compared to a polyester flower pot. So, the sensors serve multiple purposes within the Haagse Groen.”

Green monitoring platform ConnectedGreen has evolved into a ‘serious company’ within a few years after their inception


Due to more periods of prolonged drought, soils in a growing number of areas have become hydrophobic (water-repellent). The problem is that using large amounts of water when watering hydrophobic soils, is counterproductive because most of it will wash out. The solution: more frequent watering, using smaller amounts of water. The only way to manage this is through close monitoring.

Soils have pores. The size of these pores can vary, from large pores in sand to very small ones in clay. This is a useful property, because it allows the soil to provide trees and plants with moisture and oxygen.

However, if the soil dries out too far, there is so much air in the pores that they will have to be soaked for a while, until the soil is able to retain moisture again – and have it available for absorption by plants and trees. With dried-out soils, this process of re-moisturizing usually takes place during the winter time, when there is less evaporation and more rain.

By dumping large amounts of water at once, dried-out soil does not have enough time to absorb the water. This is comparable to a dry sponge or chamois that you try to push under water; it just floats back to the surface again. Only if you leave it there for a while, it gradually absorbs the water until all pores are filled.

The effect of a large amount of water at once, is very limited for the mid- and long term

Monitoring helps to better understand the ‘behavior’ of the soil and the effect of waterings. The steeper the peak on the moisture graph, the more water is washing out. By analyzing the sensor data and reviewing the graphs, it is possible to find the right amount of water to maintain the optimal average moisture percentage. Experience shows that this can save up to 70% of the amount of water. In a medium-sized municipality, this can quickly save several hundred thousand liters per growing season.

Smaller, more frequent waterings have a much longer-lasting effect

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.’

but about what’s done with the data.

In public spaces, more and more sensors are being installed. And there are many vendors diving into this topic. Things are evolving so rapidly, that Geonovum has even written a guidebook with a first draft of a ‘sensor data ordinance’ for all stakeholders involved.

Data driven operations and the Smart City are slowly but certainly becoming the new reality. Unfortunately, it is also reality that more than 90 percent of sensor data is not, or suboptimally used. This is because sensor data in itself does not mean anything. The data should be placed in a context and the information should be translated in understandable and actionable form for the different stakeholders. For that reason, the ConnectedGreen platform focuses fully on the right calibration and interpretation of sensors for landscaping, to make sure that the right information reaches the right person at the right time. Domain knowledge of trees, plants, soils and the weather is leveraged to help the users to calibrate and tune the system. This domain knowledge is crucial to make a system like this function in a practical way, and get the added value out of it.

Smart monitoring helps to work in a more sustainable way and save costs (less water, less project visits, less failing plants and trees). And through more transparency, collaboration between contractor and clients will improve. This means that all stakeholders will benefit. ConnectedGreen observes different ways of collaboration. Some landscapers deploy the system to monitor their own projects and work more efficiently. Others are also giving their clients access to the data, which enables better collaboration. And in some cases it’s the other way way around: a municipality buys the sensors to monitor newly planted trees and lets their contractor view the data.

Case: trees in Amsterdam

An example of a landscaper that is successfully using the system is the project of replacement of trees in the ‘Hemsterhuis’ neighborhood in Amsterdam. Due to circumstances, the trees had to be planted out-of-season and in extreme heat and drought. ‘We have installed sensors to keep an eye on the soil moisture situation, to make sure we water the trees at the right moment and they do not get not enough – or too much water’, says Henk Werner from Pius Floris Boomverzorging Amsterdam. ‘Three weeks after planting, the trees had developed about ten centimeters of new branches. Before the winter, new roots will have grown and the trees will be fixed, which means that they will have a head start next spring.’

Case: Smart City Houten

Of course it is important for governments to aggregate the ‘green’ sensor data on a higher level in the organization, and combine it with other (sensor) data. That is the only way to get an integrated view which is needed for developing new strategies and policies and create a ‘real’ Smart City. In a pilot project for the municipality of Houten, ConnectedGreen collaborates with partners Nazca IT and Boomtotaalzorg. Nazca IT has developed a Smart City platform, that combines data from many different sensors throughout the municipality. And ConnectedGreen is used by the municipal arborists, in close collaboration with the consultants of Boomtotaalzorg to let the newly planted ‘landmark’ Fagus Sylvatica succeed!

Houten, November 22, 2019 – Today it was finally announced: who may bring the coveted ‘Gouden Gieter’ (golden watering can) home? Setting for the festive ceremony was the Climate Expo in Houten (Utrecht). None other than ConnectedGreen and Dionysios Sofronas from Aardoom Hoveniers had the honour to receive the awards.

Author: Linde Kruese

The Golden Watering Can for ‘Best Product’ went to René Voogt from ConnectedGreen. ConnectedGreen helps landscapers and governments to save on watering, project visits and failing plants/trees. The system operates with wirelees sensors which are placed invisibly at strategic locations in landscaping projects. The sensors are available in different lengths to make sure that soil moisture levels are measured at root depth.

Sharing data
Within ConnectedGreen, projects are defined (for example per landscaping project, street or neighborhood). These projects are then divided into different indication trees, planters or beds, fitted with one or more sensors. The sensors are calibrated by entering a plant/tree name and soil type. Data can be shared between contractors (landscaping companies) and clients (governments), including notifications and alerts. This goes for both (too) dry and (too) wet situations. Besides optimization of watering, ConnectedGreen offers insights which can help improving the quality and effectiveness of growing places.

The three finalists in the category ‘Best Product’: Sharell Hogervorst from Greenmax, René Voogt from ConnectedGreen and Henk Vlijm from Optigrün

The Golden Watering Can
This year for the first time, trade journals ‘De Hovenier’ and ‘Stad+Groen’ went on a search for professionals who have developed creative, practical solutions for everyday problems that are caused by climate change. All contestants were judged by a renowned jury of experts, consisting of: Hein van Iersel (editor-in-chief of ‘De Hovenier’ and ‘Stad+Groen’), Lodewijk Hoekstra (tv-host and founder of NL Greenlabel), Egbert Roozen (director VHG), Dick Oosthoek (director Stichting Groenkeur), Ben van Ooijen (CEO/owner of De Tuinen van Appeltern) and Mathieu Gremmen (member of dike board and loco-bailiff of ‘Waterschap Rivierenland’). After the announcement, the winners were congratulated by Lodewijk Hoekstra via a Vlog.

Source: Stad+Groen

René Voogt discusses pressing issues around moisture supply for trees

When trees are being planted, several issues can arise. Moisture supply is one of those. Trees can potentially suffer from a shortage or precisely the opposite: an abundance of water. This leads to many questions for arborists, especially the question what to do about these problems.

Author: Sjoerd Rispens

In November 2019, René Voogt from ConnectedGreen won the Golden Watering Can award at the Climate Expo in Utrecht. ConnectedGreen helps landscaping companies to save on water, project visits and failing plants/trees. In ConnectedGreen, ‘projects’ are defined (for example per landscaping project, street, or neighborhood) which are divided into indication trees, planters, or beds. The sensors are calibrated by entering the tree/plant name and soil type. Besides optimization of watering, ConnectedGreen provides insights which help to improve growing places.

With ConnectedGreen, Voogt is involved daily with questions about moisture supply for trees, directly after planting. Here below he answers five pressing questions about this topic.

Question 1: How can a planting place dry out while being watered frequently?
‘Particularly in more porous and sandy soil types, like tree sand or planting soil, the process of drying can go faster than the compensation from watering’, says Voogt. ‘In certain periods, this means that watering once a week is not enough, and that a downward trend becomes visible in the moisture levels. This can even lead to the moisture level dropping to near zero between two waterings. And the more dried out, the more difficult it is for a soil to absorb water, so this is an accelerating effect (hydrophobic soil).’ The solution according to Voogt: ‘More frequent watering, in smaller quantities. These more frequent waterings can be compensated in cooler, wetter periods, when less frequent watering is required. Another option is to add more organic and/or granular material in the planting place.’

Question 2: How is it possible that rain or watering is not noticed by a sensor?
‘The sensors measure the soil moisture percentage at root depth’, explains Voogt. ‘That is roughly between 15 and 60 centimeters deep, dependable of the plants. If the top layer dries out, we observe the phenomenon that (rain)water simply washes off the top layer and cannot penetrate to root depth. This effect is called “hydrophobic” soil. In that case, the soil literally repels water. The water flows away via “flow channels” and does not enter the ground. The problem here is that the speed of drying out can be much higher than the speed with which the soil can absorb water.’ The solution according to Voogt: ‘Open up the top layer (for example with a rake) before watering or create a tree planting system, for example with reverse drainage’.

Question 3: How is it possible that different sensors in the same project show different soil moisture values?
‘This question pops up frequently when sensors show different values in beds and tree planting places that are cultivated in the same way’, says Voogt. ‘Looking through all projects in our systems, we see it is more an exception when all beds or trees in a project show the same percentages. Here, several variables are in play:
-The interaction between the top layer, underground, cultivated soil and root ball. Especially the top layer and underground are very divers in our country. Also, the soil that is added to the project is not always exactly similar in every bed or with every tree.
-The shadow of buildings or other plants/trees plays a rol, besides orientation/vulnerability to the sun or wind.
-Sometimes, very local impermeable layers or horizontal water flows play a role.’

Question 4: How come that some growing places are wet in the top layers and dry at the bottom, while this is the opposite for other growing places?
‘Here too, environmental factors play a big role. Soil with a high amount of organic matter can hold moisture very well. Sometimes, there is more organic matter in the top layers and sometimes more in the lower layers. Besides that, the drainage capacity of the growing place is essential. If an impermeable layer or heavy clay is present, we often see the growing place ‘filling up’ like a bathtub. First the moisture levels rise in the lower levels, and then in the top levels too. We also see the opposite, when plants and trees are planted on a slope or very sandy underground and the water just flows away.’ The solution according to Voogt: ‘Impermeable layers or clay can be penetrated or dug up. In very porous soils it will help to add clay to the bottom of the planting hole.’

Question 5: Why is the soil moisture percentage a few days after a(big) watering sometimes lower than before?
This is a remarkably interesting phenomenon, that Voogt has encountered in a couple of occasions: ‘After watering, the moisture percentage rises really quickly, to then drop dramatically. It is widely known that excess water drains away if it is much more than the soil can hold/absorb. It seems that, in certain situations, the water that is already present, is ‘drawn down’ with the water that flushes out. We have seen this in a couple of places. There are several theoretical explanations, but additional research is needed to find out the real cause. The observed pattern seems to support the theory that it makes no sense to give (much) more water than the soil can hold (more than the field capacity). On many graphs in the summer period we observe these high peaks, followed by lower levels than before. The preliminary results with giving less water (30 to 50 percent of the original quantities) are indicating that the soil moisture percentages drop much less quickly, thus being better maintained.’

And as afterburner: why is it important to receive a signal if the growing place is too wet? Aren’t these sensors meant for watering in case of drought? Voogt: ‘After having hundreds of sensors for more than two years in the field, we know that it is evenly important to receive signals if it is wet, even in wintertime. There are several examples known of projects where many trees and plants have failed due to an abundance of water. This can have many causes which were not known in the design phase, like:
-The growing place or bed is lower than the rest of the area, so all water flows there
-There is an impermeable layer or heavy clay, which prevents excess water from draining
-The planting place is next to a (sloping) road, a square or path, which makes all water flow in one direction
-The soil contains too much (raw) organic matter, holding large quantities of water
Often the notification “too wet” comes as a surprise (we have seen more than one occasion of broken water pipes or valves). It is however extremely useful to know, because the cause can be investigated and taken away – for example with vertical or horizontal drains.’

Source (NL): Stad+Groen

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