Lower Guadalquivir Valley, southern Spain
The IRRI-SP is situated in the rice-growing area on the marshes of the Lower Guadalquivir Valley. The area comprises about 35,000 ha of marshes located next to the estuary of the Guadalquivir River and between the river and Doñana National Park (UNESCO Biosphere Reserve). Rice production is the basis of the economy in the area, and rice growers are organized in the rice growers’ federation and water users’ associations.
Land productivity is high (average yield near 10 tons per hectare). The irrigation water comes from the general regulation system of the Guadalquivir basin. Part of the water supply comes from a canal diverting from upstream, but the largest share is pumped directly from the river estuary. Water restrictions due to rainfall and reservoir storage variability is the main threat for rice production in the Guadalquivir marshes. Since most of the irrigation water is pumped from the river estuary and the rice-growing area is underlain by a saline shallow water table, salinity is the second major problem.
The rice industry is currently investing in R&D by testing water saving practices in large farms. Water Users Associations (WUA) and irrigation equipment companies are searching for innovative practices to save water. The sector cohesion in the Lower Guadalquivir Valley, ensured by the rice growers’ federation and the water users’ associations, is of great value for this endeavor.
Preliminary yield benchmarking was carried out with TEPRO (Associate Partner), who was the one in charge of the field management. The quality of the irrigation water varied from field to field, and was estimated in terms of electrical conductivity using the data provided by the Guadalquivir river basin authority, the WUAs and the rules followed at the pumping stations for setting salinity thresholds to stop pumps. Apparently, 1.5-2.1 dS/m would be the threshold of irrigation water salinity above which yield decreases at a rate of 3-4 Tn/(dS/m). However, the variability of the yield gap is notable, up to 30%.
The three sites selected in the IRRI-SP hub are the Desmaisieres farm, the Comunidad de Regantes Sección Primera de Marismas, and the rice area on the right bank of the Lower Guadalquivir Marshes.
Site 1: Desmaisieres Farm
Desmaisieres farm, managed by Tepro, is on the right bank in Isla Mayor (Seville). This farm has a total area of 23.8 hectares. The farm is divided into 4 fields. The entire farm was monitored during the rice campaigns of 2019 and 2020, implementing 3 irrigation strategies (prolonged drying periods, inflow/outflow reductions, recirculation) compared to a 1 control field. The site was shared with the project MEDWATERICE.
Site 2: Comunidad de Regantes Sección Primera de Marismas
Comunidad de Regantes Sección Primera de Marismas is on the left bank in Los Palacios-Villafranca (Seville). This WUA is was interested in developing methods to estimate discharge at the farm outlets. During the rice campaign of 2020, a pilot dispositive was installed in one farm of the WUA under supervision of the WUA. In collaboration with the project MEDWATERICE, discharge measurement procedures and software (named QoZ) have been developed based on intensive field measurements and hydraulics.
Site 3: Rice area on the right bank of the Lower Guadalquivir Marshes
The upscaling of on-farm water saving practices in the Lower Guadalquivir Marshes was carried out by modelling water circulation in the right bank that covers 22,000 ha of paddy rice and encompasses more than two thirds of the rice growing area in the Lower Guadalquivir Marshes. A water and salt circulation model has been developed for this area in collaboration with the MEDWATERICE and ORYZONTE projects.