Suitability assessment of treated wastewater with various dilution levels for irrigation in a rain-fed area: implications for crop growth and element translocations in Sorghum bicolor (L.) Moench

Kinmen, primarily reliant on rain-fed agriculture, faces persistent water shortages. This study investigates the potential of Kinmen Kaoliang Liquor Inc. (KKL) effluent, diluted with Houlong River (HR) water, to address water scarcity and assess its impact on sorghum yields, as well as the accumulations of macroelements (P, K, Ca, Mg, Na) and heavy metals in soils and plants. Results indicate that sorghum yields (2733.33 kg/ha) were optimal for the 40% KKL treatment, followed by the 80%, 60%, 20% KKL treatment, with the control treatment using HR water yielding the lowest. Macroelements exhibited distinct distributions in various plant parts. The distribution of P and Mg was highest in the leaves and grains, followed by the stems and roots for different KKL treatments. The order of Ca concentration was leaves > roots and stems > grain, while that of Na was roots > stems > leaves > grains. However, the distribution of K varied between the 20% and 40% KKL treatments (stems and leaves > roots > grains) and the 60% and 80% KKL treatments (roots > stems > leaves > grains). The findings emphasize the importance of understanding the intricate relationships among various elements within plant physiological processes. The macroelement mass balance in water-plants-soils revealed a decline in P and Mg portions stored in plants with higher KKL treatments, while Ca, K and Na portions varied across KKL treatments. In summary, considering sorghum yields and macroelement accumulation in plants and soils, the 40% KKL treatment is recommended for irrigation as an effective solution for water scarcity in Kinmen.