Monitoring soil quality with underground drip irrigation

Climate change requires more efficient use of water. Problems with salinity of the groundwater are lurking, especially in the coastal provinces. In order to provide crops with sufficient water in arable farming, new techniques are needed that prevent water wastage. In Deltadrip, these techniques are tested, and we look at their effect on the soil structure.

Combating salinization of scarce freshwater

In the coastal area, the deeper groundwater is saline, which means that there is a risk of salinization of the scarce fresh groundwater when there is a lot of groundwater abstraction. Groundwater is extracted for irrigation during dry periods, which become more frequent and more intense due to climate change. In the Deltadrip project, we are investigating, on an arable plot in Zeeuws Vlaanderen, to what extent water and nutrient savings are possible through innovative use of drip irrigation and fertigation, as an alternative to traditional irrigation techniques and fertilisation methods. Within this project, the Louis Bolk Institute focuses on the effect of drip irrigation on the soil structure. Interestingly, the drip irrigation on the trial plot was also installed underground (see photo). This limits water and nutrient losses by bringing them close to the roots. Moreover, such a system does not have to be re-installed every season, since soil cultivation can be done on top.

Testing an underground drip irrigation system

The soil structure was monitored for two years (2019-2020). Here, reel irrigation was compared with underground and above-ground drip irrigation. The construction of an underground drip irrigation system appears to cause little structural damage.
At the start of the project it was expected that the soil structure with drip irrigation might improve compared to reel irrigation. This is because droplet impact during reel irrigation can cause erosion, and therefore lower the stability of the soil. Better, deeper rooting was also expected as the water is supplied from below instead of from above. However, the results to date have failed to show this. Above-ground drip irrigation does, however, yield good results in onion cultivation. This shallow rooting crop benefits from the superficially and directly applied water.
Results of the water consumption and crop yields of the various irrigation techniques are expected shortly. This knowledge gives growers the opportunity to make an informed decision about which irrigation technique suits them best.

Partners and implementation

Deltadrip is being carried out by AcaciaWater, the Louis Bolk Institute and Delphy on a plot of Maatschap Waverijn.

Download the 2019 survey results here

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