Salinization pattern and its spatial distribution in the irrigated agriculture of Northern Ethiopia: An integrated approach of quantitative and spatial analysis

摘要

Salinity adversely affects the environment, agro-ecosystems and agricultural productivity of arid and semi-arid regions worldwide. This salinization occurs due to natural, human or both actions on the dynamic earth system. This study was conducted to quantify the magnitude and map the spatial distributions of salinity of the irrigated agriculture in northern Ethiopia. A total of 717 soil and 13 water samples from nine irrigation schemes were used for analysis. The soil samples were collected on a grid basis from 0 to 15 cm and 15-30 cm soil depths in the plant's root zone whilst surface water samples were collected from the irrigation water source, middle and lower cross-sections of the irrigation schemes. These soil and water samples were analyzed quantitatively for 14 salinity parameters and results compared with worldwide standard values. In addition, the spatial analysis was made for three basic salinity parameters of hydrogen ion concentrations (pH), Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR). Even if, there are non-significant variations between soil depths and among the irrigation cross-sections, a salinity is observed at 33% of the schemes. Higher pH average values are spatially concentrated downstream whilst SAR and EC showed inconsistent variations among irrigation schemes. The quantitative and spatial salinity analysis revealed that Gum Selassa, Gereb Kunchi and Tegahne irrigation schemes have potential salinity levels. As a result, salinity management strategies and community-based salinity management approaches that involve farmers' participation is vital to create a sense of ownership. Irrigation users and decision makers should consider possible measures of minimizing salinity build-up thereby increasing agricultural productivity in a sustainable way.