In some areas of the world 80 percent of the water resources are used for irrigating agricultural crops. This is not feasible in the long run because water is increasingly becoming in short supply. FAO reports that a reduction of water used for irrigation by 10 percent would correspond to the amount used in all households in the world.

Research results from the Faculty of Agricultural Sciences, Aarhus University, have previously shown that it is possible to save 20 percent of water used for irrigating potatoes. Scientists from Italy have shown similar results in studies with tomatoes and the system has been tried on tomatoes not only in Italy but also in China and Crete as part of the international EU project SAFIR.

Now the potato and tomato results will benefit farmers in even more countries. The research results have been integrated into computer models that farmers and their advisers can use directly, thus paving the direct road from science to farming.

In Denmark the results from the potato studies at the Faculty of Agricultural Sciences have been entered directly into ”DAISY”, a simulation model from the Faculty of Life Sciences at University of Copenhagen that is the world’s most advanced model of its kind. Farmers can use the model to control irrigation and optimise growing. The model takes into consideration just about everything from sowing to harvest, such as weather conditions, fertilisation, soil conditions, crop type, nitrogen leaching – and now also the new irrigation method.

Alternating irrigation reduces water consumption

The new irrigation method – alternating irrigation or PRD (partial root zone drying) – involves watering the crops on first one side then on the other side. By alternating sides each week the plants receive a certain portion of water but are still a bit drought-stressed.

The method stimulates the plants’ own ability to save water by stimulating sensors in their root tips, which in turn stimulates production of the plant hormone abscisic acid. The hormone makes the plant’s stomata close, which reduces evaporation from the leaves.

Studies with potatoes at the Faculty of Agricultural Sciences have shown that the method can reduce water consumption by 20 percent without decreasing yield. However, if the plants are irrigated in the conventional way, i.e. on both sides of the plant at the same time, but with the same reduction in the amount of water, then the yield will be less.

The results from the studies have now been reviewed and published in four international journals. They have also been integrated in the computer model DAISY, which can now show how much water can be saved under various climatic conditions and how much irrigation efficiency can be increased.

A corresponding model, SALTMED, but which is designed for dry areas, has been developed by English scientists in the SAFIR project. The model takes into consideration that in dry areas of the world there are problems with soil salination. This occurs because there is salt in the irrigation water and the salt is not leached in the winter because it does not rain so much in these areas.

According to new studies from the Geological Survey of Denmark and Greenland (GEUS), it is likely that water requirements will increase by 100 percent in Denmark as a result of climate change. It will therefore be even more important to find water-saving methods, including in Denmark. There is probably enough water in the groundwater but more efficient water consumption will lead to economic savings for the farmer.

Facts about SAFIR:

- A total of 7.1 million EUR, including 4.7 million EUR from the EU, has been granted to the project.

- Participating in the project are 17 partners from 10 different countries, including EU countries, China and Israel.

- The Faculty of Agricultural Sciences is the coordinator of the project.

- SAFIR is the acronym of the project and stands for “Safe and High Quality Food Production using Low Quality Waters and Improved Irrigation Systems and Management”

- You can read more about the SAFIR project at www.safir4eu.org .

For more information please contact: Senior scientist Mathias Neumann Andersen, Department of Agroecology and Environment, Aarhus University, telephone: +45 8999 1742, email: MathiasN.Andersen@agrsci.dk

Text: Janne Hansen