Making Self-watering Fruit Trees a Reality
The start of the growing season raises the issue of optimal irrigation in fruit production. Thanks to digital measurements, trees on pilot farms are only being irrigated when necessary, thus saving water. An Agroscope video shows how this works.
A dendrometer is a device placed around the trunk of a tree to measure changes in its diameter. Trunk-diameter shrinkage automatically triggers irrigation. Unlike with conventional systems, irrigation thus only occurs when the tree genuinely needs water. This approach could mean water savings of up to 40%.
Measuring water stress at the plant rather than in the soil
Thomas Anken, Head of the ‘Digital Production’ Research Group, has already received feedback from practitioners: “On the occasion of the project launch, farmers showed a keen interest in the wide range of measures for optimising water use. Compared to automatic control systems which measure soil moisture, dendrometers offer greater benefit by measuring the effective water stress of the plants. The notion that the dendrometer system actually functions as simply and reliably as in the Agroscope studies is currently still met with scepticism, however, which is why the system is being tested on pilot farms in the Canton of Thurgau.”
Water savings on deep soils in particular
Asked whether water savings of 40% are truly possible under practical conditions, Thomas Anken replies: “This depends on the natural conditions and previous management. On deep soils, trees can supply themselves with water from a depth of several metres, which cannot be detected with the usual soil moisture sensors. In such cases, very high savings are possible with dendrometers, whilst on shallow soils good results are also achieved with soil moisture measurements.”
Costs of CHF 3000 - 4000
For farmers, costs are an important consideration in addition to efficiency and practicality. Thomas Anken has good news in this regard: “Per plot, we reckon on 4-5 sensors, which are mounted on different trees. Costs including tax are likely to range between around CHF 3000-4000. Things are still in the development stage, however, and depend heavily on how many farms are interested, since sensor costs are heavily dependent on volume. If farmers already have an irrigation system, the purchase price will be less.”
Projects
- Ressourcenprojekt Integrales Wassermanagement: Agroscope, Kanton TG. Lead: Rainer Messmer, Kanton Thurgau.
- Projekt von Agrofutura: Agroscope, Agrofutura AG, Kanton AG, LU, BE, SZ, UR, ZG. Lead: Annelies Übersax, Agrofutura AG.