The project to test sensors in urban farming is a part of Smart Public Environments (SOM) – where the Internet of Things (IoT) is used to make life easier for the municipality and its citizens. The concept is that farmers should be able to take advantage of sensors that warn via, for example, text message if the plants’ living environment is poor. In addition, sensors that measure humidity can be used to make better decisions about the time to water the municipality’s plantings – and in this way the municipality can avoid both unnecessary irrigation and dehydrated plants and thus save money.  

On the hill below Max IV lab at Brunnshög in Lund there are farming allotments. The area has clear sustainability attributes and enthusiasts with their own plantings can grow flowers and vegetables. The farmers’ association also has a greenhouse where Mikael Hellberg and Janine Österman grow tomatoes, peppers and cucumbers. The crops in the greenhouse are sensitive to high humidity and high temperature and therefore, if something goes wrong, the sensors can warn the farmers via sms. When an alarm is sent the indoor environment can be regulated by the opening of doors and windows.

- We have measured very high temperatures and when it gets too high the plants suffer and can be easily damaged, says Anders Hedberg, sub-project manager in SOM and CEO at Sensefarm. With this type of measuring equipment, you get better harvests and you also do not have to use poison against vermin that can become infested when the living environment is poor.

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Close to Malmö central station there is the newly built Bastion Uppsala. Amongst the trees, grass, bulbs and perennials the municipality has buried monitoring instruments so that the plants receive the correct amount of water.

- In this park we have installed humidity sensors in two places, explains Sam Madsen. We have chosen to place them in two different soil substrates in order to measure which substrate holds moisture the best. In each substrate there are two sensors that measure humidity at different depths so that we can also see how much water penetrates into the soil.

The readings are passed on so that the Service Department can examine on their computers when is the right time to water the plants. The reading will also provide information about how much water penetrates down to the tree roots. For cities that have very large areas of crops to manage it can save a lot of money if you water at the right time and not when you think it is time.

For it to be possible to receive signals from a sensor in the allotments to a computer, a sensor network is needed. In both Lund and Malmö there are LoRa-networks that are part of the test bed for the project.

- LoRa is a new type of radio technology for smart cities, explains Anders Hedberg. LoRa technology is fanastic and allows you to build networks as you wish and then set up sensors where you need them. LoRa provides good coverage and allows you to build a smart city in a more cost-effective way.

The sensors are not connected the whole time but send their readings at pre-installed time intervals. This means that the batteries can last much longer, which is a big advantage as you do not have to spend as much time replacing batteries.

Smart Public Environments (SOM) is a project in both Lund and Malmö municipalities together with IoT Sweden with support from Vinnova.

Caption, big picture: Mikael Hellberg and Janine Österman from the Brunnshög farmers association in the greenhouse that is managed with the help of sensors.

Translation: Ben Dohrmann