In a European Innovation Project, one objective was to evaluate the water saving potential of variable-rate site-specific irrigation in a lowland area of Eastern Germany. This region is increasingly prone to early summer droughts, which in combination with mostly sandy soils challenges rainfed agricultural production. Irrigation farming therefore gains importance but due to locally decreasing groundwater levels and limited surface water availability, water withdrawals are subject to restrictions. Hence, it is mandatory to use irrigation water is efficiently as possible.

In our project, we equipped two centre pivot irrigation machines with full VRI systems, which allow for individual nozzle control. The fields, where the pivots are located, show substantial soil heterogeneity. Both fields are managed by farmers with crop rotations that are typical for the area (winter wheat, silage maize, potatoes). In order to evaluate the water saving potential under real-world conditions, the farmers are fully responsible to run the machines. The timing and amount of irrigation is calculated with an irrigation control software based on prescription maps.

In this contribution, we present our two year experience with the VRI systems in addition to simulation results for a twelve-year crop rotation. We compare variable-rate irrigation not only with uniform irrigation but also with different deficit irrigation strategies. Yield results are also included in our evaluation. Finally we draw conclusions about the potential for regional adoption of the technique based on our results and the farmers' experience.