Blueberry farming requires regular irrigation to grow the fruit into a beautiful, juicy berry. But of course, irrigation should be used intelligently. When it rains and the soil is already saturated with rainwater, there is no need for additional irrigation. Water sensors in the soil measure soil moisture and help direct irrigation.
Smart minds from pcfruit vzw and the Proefstation voor de Groenteteelt sat down together in the Interreg project 'Smart Growers'. They were determined to save even more water when harvesting blueberries!
Blueberries consist of 85% water. This means that even short periods of drought are disastrous for harvesting blueberries. The fruit stops growing, and small berries cause the grower to receive a much lower price.
The berries grow best when the bushes receive precision irrigation: drops of water that go directly into the relatively small root zone. The amount of water flowing through this irrigation is adjustable.
Blueberries are acid-loving plants, which means that in addition to acidic soil, they also desire acidic water: rainwater, for example. Besides, using rainwater saves tap water at the same time!
Sustainable blueberry farming bears fruit
Smart Growers took irrigation with a water balance model to the test. The "balance" at issue in this model is the one between the water that leaves the plant's root zone every day (evaporation) and the water that comes in (rain and irrigation). This balance is kept by irrigating exactly the amount of water needed. This ensures that the soil in the root zone does not become drier than the maximum tolerable desiccation.
Is only such a minimal amount of water really needed for a perfect crop? Even for drought-sensitive plants like blueberries? The answer was yes!
When a blueberry farmer uses the water balance model in combination with smart irrigation, their own weather station and monitoring system, they can save a great deal of water. Something very valuable in these times of water scarcity.
Saving water when watering blueberries is another step toward smart agriculture.
As shown in the photo above, blueberry bushes have a small and rather shallow root zone. Precision irrigation is therefore very valuable.
Smart agriculture automates and innovates
The goal of this project was to have software calculate the watering rate per day and automatically communicate this to the blueberries' irrigation system.
To apply irrigation with a water balance model, a number of things had to be measured. For example, daily water evaporation from the previous day had to be calculated and rainfall had to be measured (via data from a local weather station and radiation meter). This evaporation is calculated based on wind, temperature, relative humidity and radiation.
With this, the Proefstation's water balance program calculated how much more water needed to be added the next day. Diagro's software then retrieved this calculated number via the API of the water balance program. Through our relay output module, the program was then able to automatically open or close the irrigation valve to administer this amount of water. The amount of water effectively administered was measured by a water counter on Reporter. Diagro's software relayed this value at the end of the day via API to the water balance program. Then the watering rate for the next day could again be calculated for watering the blueberries.
All irrigation models are prone to errors that can accumulate, causing the modelled soil moisture condition in the root zone to no longer reflect reality. Therefore, it is important to keep measuring the actual soil moisture condition, and to calibrate the model when it deviates too much from reality. For this purpose, the different soil moisture sensors were addressed.
Tasty blueberry farming at 50% less water consumption!
It turned out that more water was added each day than what had evaporated. Precious irrigation water was washing away unused into the deeper soil every day. Rain could not be absorbed by the root zone because it was continuously saturated with water. This left room for improvement and water gain. As a result, using the water balance model, they grew the same number of kilograms per plant of equally large, sweet and juicy berries. At half the watering rate compared to the control group.
In the table below you can see the comparison between the control group (blue) and the bushes that were watered according to the water balance model (orange). It becomes clear that the two groups perform equally well.
So watering blueberries is perfectly possible in a smart and sustainable way!
Sustainable doesn't have to be expensive
Before pcfruit approached us for this project, they had already presented the case to several other companies. Remote monitoring with all these different sensors seemed quite a challenge. 'Difficult', 'expensive', 'troublesome' and 'complicated customisation' they were told. But all those comments were very unjustified.
"The possibilities for monitoring and automatic control of devices via utilities make Reporter a handy tool for irrigation control - for researchers and growers alike."
- Bart Vanhoutte, pcfruit
Reporter is a simple and also versatile solution when you want to combine different sensors within a project. The simple plug-and-play system allows you to put together your own affordable sensor module.
A colourful collaboration for blueberries
This research on harvesting blueberries is part of the Smart Growers project, funded within the Interreg V program Flanders-Netherlands, the cross-border cooperation program with financial support from the European Regional Development Fund, VLAIO and the provinces of Limburg, Antwerp and East Flanders. This European Fund supports interregional developments, such as smart agriculture here.
The trial was conducted by Proefcentrum Fruitteelt in cooperation with the Proefstation voor de Groenteteelt. The water balance model was developed by the Proefstation (formerly PSKW). They carefully studied irrigation, how much water was given per day to a row of bushes to grow blueberries. After finding the right amounts, they built the water balance model.
In short, this colourful collaboration ensured rapid advances in irrigation research.
pcfruit, with special thanks to Bart Vanhoutte.