S12 - Session P3 - OrnAqua: an irrigation reference framework for efficient water use in hardy nursery stock production

Authors: Paulien De Clercq *, Pieter Janssens, Kathy Steppe, Dominique Van Haecke, Bruno Gobin, Marie-Christine Van Labeke

Over the past years, we have been experiencing more extreme weather conditions during the growing season with prolonged drought periods. Drought clearly has an economic impact on plant quality of woody plants. To reduce the impact of drought risk, growers have a demand for suitable tools including soil and plant sensors to control irrigation. The overall objective is to provide growers with tools to rationally and sustainably schedule irrigation to ensure the commercial quality. Trials will be performed on two cropping systems: avenue trees ( Carpinus betulus ) and forest transplants ( Acer pseudoplatanus ). Trees and transplants (1+0) will be planted in autumn 2021 (sandy soil) and trials will start in spring 2022. A non-irrigated treatment will be compared with an irrigated treatment according to daily water need. Water need will be defined by estimation of evapotranspiration (ET) and observation of rainfall and soil hydraulic properties. Drip irrigation will be applied for avenue trees, and overhead irrigation for the forest transplants. Four replications per treatment will be monitored. Soil water status will be monitored using sensors and biweekly soil samples. Sap flow sensors will be used to measure the transpiration of the crop during the growing season and proximal sensing and dendrometers will be used to detect stress. Based on these data sets, the ET of the crops and irrigation thresholds which indicate the economic loss in function of soil and plant potential will be determined. These thresholds can be used in combination with soil water balance calculations to forecast irrigation needs. Preliminary data of the first growing season will be presented.