Impact of saline irrigation water on soil sodicity and crop performance in arid regions

Abstract:

Managing soil sodicity in arid zones where the only available irrigation water is itself saline presents one of the toughest challenges in dryland agriculture. This research tracked changes in soil exchangeable sodium percentage (ESP), electrical conductivity (ECe), and crop yield across five salinity levels of irrigation water (1.2-12.3 dS/m) over four consecutive cropping cycles in the arid Llanos region of Colombia. Field trials ran from March 2022 to November 2024 on a Vertic Haplustalf at the Instituto de Ciencias Agrarias del Llano, Villavicencio. Soil ESP increased linearly with irrigation water EC (R² = 0.98), crossing the sodicity threshold of 15% at approximately 3.8 dS/m. Maize suffered the largest yield decline (23.4%) followed by sunflower (18.9%) and sorghum (14.7%), while barley proved the most tolerant (8.6% loss). Gypsum amendment at 5 t/ha reduced ESP buildup by 37.2% compared to unamended plots. These results indicate that irrigation water above 4 dS/m poses a serious sodicity risk without active soil amendments in arid Colombian soils.