Desalination in agriculture: short-term field responses of banana crops irrigated with blended groundwater and desalinated seawater in the Canary Islands, Spain

This research studies the effect of combining local groundwater (GW) and desalinated seawater (DSW) on a banana farm and the conservation of agricultural soils in Buenavista del Norte, in the northwest of Tenerife. The groundwater in this region is characterized by its high alkalinity due to subsoil volcanic activity. In recent decades, the increase in the volume of water extracted from wells in the area has caused a rise in its salinity. In the experimental design of the trial, a mixture of DSW and GW in different proportions was applied to four irrigation treatments, which consisted of 100% GW, 33% DSW + 67% GW, 67% DSW + 33% GW, and 100% DSW. The experiment was conducted using a Randomized Complete Block Design (RCBD) with four treatments and four repetitions. Plant growth and productivity, as well as plant and soil chemical parameters, were measured. The results indicate that fertilizer application to the different water mixtures increased the calcium concentration. This increase reduced the potential risk of corrosion of metallic components in the irrigation system (LSI ≈ 0) and minimized the likelihood of adverse effects on soil water infiltration capacity. These findings suggest that prior remineralization of DSW may not be required when appropriate fertigation practices are implemented. No significant difference in vegetative development among treatments was detected. Two years after beginning the experiment, leaf nutrient analyses indicate that there are no significant differences between treatments (p ≤ 0.05) in K, Ca, Mg, Fe, Cu, and B. The N, P, and Zn levels tend to decrease as the proportion of DSW increases.