Decision support for drought-adapted irrigation management

The objective of REDSIM was improving Irrigation Water Productivity (IWP) in these two water-stressed watersheds, by developing and validating an Information-Decision Support System (REDSIM-IS) based on remote sensing data and simplified water balance and crop models to assist growers in implementing and managing efficiently deficit irrigation (DI) techniques.

Key activities carried out were the (1) setting up and calibration of the REDSIM information system (REDSIM-IS) and farm advisory tools, (2) the mapping and prediction of soil and crop attributes, surface fluxes, rainfall, soil water balance and IWP, and (3) the implementation and monitoring of the irrigation treatments in pilot farms, on-farm evaluation of the acceptance of the REDSIM tools.

The REDSIM information system was successfully implemented during the project and farm-level evaluation has been done with a group of farmers. Deficit irrigation strategies were tested in various crops during the project period and results were synthesized for dissemination among farmers. The REDSIM trials showed that IWP can be increased by around 20% in citrus orchards and melons, 30% in Nectarines orchards and about 60% in vineyards, compared to conventional irrigation strategies.

Given the importance of these crops in the Mediterranean areas, and the fact that the level of knowledge and number of tools for DI are increasingly available to the farmer, REDSIM confirms that there is a significant potential to increase the economic output of irrigation water in this area, and to promote its sustainable use.  Farmers should however have easy access to this knowledge (for example guidelines brochure of REDSIM, capacity building, demonstration projects), and should be supported through REDSIM-like information systems.

Other key findings:

• The potential to increase water productivity by changing irrigation practices is substantial, even in irrigation districts equipped with modern infrastructure (e.g. Campo de Cartagena, S-E Spain) where drip irrigation is fully implemented. Over-irrigation is common and deficit irrigation techniques are hardly practised due to lack of proper crop-specific guidelines and information systems that provide the necessary information on crop water demands.
• Fine-tuned drip irrigation may, in combination with deficit irrigation techniques, ensure that these saving potentials are exploited. Water consumption can be reduced and IWP increased by up to 40% for different fruit crops. Farmer information and advisory systems are essential to support these water saving strategies.
• To this end, irrigators should become acquainted with the use of advanced irrigation management tools and become more familiar with deficit irrigation techniques, through better science communication, demonstration projects and capacity building. This is likely to have a beneficial impact on WP and sustainability of irrigated agriculture in semi-arid countries.
• Certainly, economic incentives are deemed necessary to motivate irrigators to adopt and successfully implement advanced irrigation methods and supporting tools. Also irrigators’ associations can play a key role in fostering DI and its uptake by farmers.
• Combining and processing ground and RS-based spatial datasets of crop/soil indicators within integrated information/advisory systems is highly recommendable for optimizing irrigation management and increasing WP. In particular, there is scope to include radar-based rainfall mapping (QPE, quantitative precipitation mapping) in plot-level irrigation planning, especially in Mediterranean areas with a where rainfall is extremely variable in space and time.

Reports can be downloaded from www.futurewater.nl.