Trees Indicate Water Stress Online
Digitally monitored trees indicate when they need water, so the irrigation system only supplies water when necessary. According to a recently published article, this can help achieve water savings of up to 40%.
A dendrometer is a device placed around the trunk of a tree that measures changes in the trunk’s diameter. When it sends its data via the internet or radio to the irrigation system in the field, trunk-diameter shrinkage triggers irrigation. The innovation here is that instead of using the usual soil-moisture sensors, the tree transmits data on its water requirement directly.
Water savings of 40% achieved in study
Thainna Waldburger, a PhD student at Agroscope and the ETH, has been studying the best way to implement this Smart Farming technology in apple orchards since 2021. The first year was too wet; the researcher acquired the best data in 2022 and 2023. The experimental design contained four different treatments:
- Full irrigation (100% water) via sensor data on soil moisture
- Reduced irrigation (70% water) via sensor data on soil moisture
- No irrigation
- Irrigation based on dendrometer data on trunk diameter.
The results are impressive: water savings of 40% were made with no significant reduction in yield. The yield therefore remained practically the same as for irrigation via sensor data on soil moisture (100% water), whilst requiring only 60% of the water volume. Thanks to the dendrometer, the water could be supplied precisely when the tree needed it.
Practicality is the aim
Previously, the experiments took place in the Canton of Vaud. Now the project is being continued on other experimental plots in the cantons of Thurgau and Schaffhausen as part of the Smart Technologies’ Experimental Station, with not all trees, but just a few, being ‘digitalised’. Care must be taken to include trees of different ages, or trees planted in different soils. It will be some time until the system is market-ready, however. What is already clear is that the purchase is worthwhile for farmers who already have an irrigation system in place. The complicated part of the system is the installation of the sensors, which must be done properly. One alternative for practical use could be even more interesting: the fruit dendrometer. A device of this sort is easier to instal than a trunk dendrometer, and records harvest maturity as well as water stress. Moreover, it works in tomato and apricot crops, as other Agroscope researchers have discovered.
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Self-irrigating apple trees
Climate change has made the sparing use of water increasingly important. We are therefore studying the possibility of reducing water consumption in orchards through prudent management. To this end, we use the natural reactions of trees to manage irrigation.
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