Impact of fish farm drainage water reuse for irrigation on barley yield and water productivity: Field study and simulation using the SALTMED model

Abstract

Countries such as Egypt, which are situated in semi-arid regions and have water constraints, primarily aim to repurpose unconventional water resources for irrigation. The aim of this research was to examine the feasibility and advantages of irrigating barley with fish farm drainage water (DWFF) rather than fresh irrigation water (IW). Four degrees of deficit irrigation [100% FI (full irrigation), 80% FI, 60% FI and 40% FI] were studied for the irrigation of barley via two types of water (DWFF and IW). The response of crops to a deficit irrigation approach involving the use of IW in the two seasons of 2020–2021 and 2021–2022 was demonstrated by the results. The yield of the barley produced with DWFF irrigation was greater than that produced with IW irrigation, ranging from 9% to 12% in 2020–2021 and from 9% to 13% in 2021–2022. This resulted from the higher concentration of dissolved biological nitrogen and other nutrients in DWFFs. There was a strong correlation between the observed and simulated crop yield values for both growing seasons, with R² values of 0.963 and 0.960, respectively, for all the treatments. The SALTMED model was used to simulate the soil moisture content, water application efficiency, barley dry matter, yield and water productivity for all the treatments. The study concluded that DWFF is a useful irrigation substitute for IW. Higher yields were also attained with the use of less IW and chemical fertilisers because of the DWFF. In addition, there are other advantages, such as increasing farmer income and lowering discharge to the drainage network.