MALT BARLEY (HORDEUM VULGARE L.) WATER USE AND GRAIN YIELD RESPONSE TO SALINE IRRIGATION UNDER SHALLOW GROUNDWATER TABLE CONDITIONS

Global water scarcity and salinity of irrigated lands remain a concern. Shallow groundwater tables, often present in irrigation areas, may serve as energy-efficient water sources, but they may also restrict leaching. This study quantified the salinity effects on water use and grain yield of irrigated malt barley in the presence of a shallow groundwater table. A lysimeter experiment was conducted over two seasons on sandy and sandy loam soils in Bloemfontein, South Africa. A Cocktail barley cultivar was irrigated with five irrigation water quality levels (ECi), i.e. control (1.5), 4.5, 6, 9 and 12 dS m(-1). Salinity of the constant (1.2 m) groundwater table corresponded to ECi. Saline irrigation water had cumulative depressive effect on evapotranspiration, groundwater table depletion and grain yield as well as water productivity. Increasing ECi from the control to 12 dS m(-1) reduced grain yield by 91 and 89% for the sandy and sandy loam soil, respectively, in the second season. The relationship between grain yield and salinity was dynamic (R-2 = 0.8) and more sigmoidal than linear. Given the fluctuating nature of shallow groundwater and its close association with periodic waterlogging, revision of salinity threshold values and yield-salinity relationships for major cash crops remains critical. (c) 2019 John Wiley & Sons, Ltd.