Empirical Analysis of the Effect of Saline Irrigation Water on Crop Yields in the Lake Chad Basin Agricultural Zone

Progressive salinisation of shallow groundwater used for irrigation in the Lake Chad Basin area threatens the sustainability of dry season crop production in Borno and Yobe States, and empirical characterisation of the yield impacts of different salinity levels across major crops guides irrigation water quality thresholds and management advice. This study empirically analysed the yield effects of three irrigation water salinity levels (0.5, 2.0, and 4.0 dS m-1 representing low, moderate, and high salinity) on four major crops (wheat, tomato, cowpea, and pepper) at the University of Maiduguri Research Farm, Borno State, North East Nigeria. A factorial experiment in a randomised complete block design with three replications was conducted during the 2022-2023 dry season. Soil electrical conductivity, plant height, and grain or fruit yield at harvest were measured. Results showed that cowpea was the most salt-tolerant crop, with only 11.3 percent yield reduction at 4.0 dS m-1 compared to the 0.5 dS m-1 control. Tomato showed 48.7 percent yield reduction at 4.0 dS m-1, while pepper showed 57.4 percent reduction. Wheat showed the most complex response, with moderate yield reduction at 2.0 dS m-1 (14.2 percent) and severe reduction at 4.0 dS m-1 (43.1 percent). The study provides empirical data to establish crop-specific irrigation water salinity thresholds for the Lake Chad Basin zone and recommends cowpea as the most appropriate crop for saline irrigation water conditions in the region.

Keywords: saline irrigation, crop yield, Lake Chad Basin, salinity tolerance, Borno State