Spatial and temporal analysis of irrigation water and soil quality in the Achewa small-scale irrigation area, Southwestern Ethiopia

Irrigation water quality varies spatially and temporally due to factors like landform, geology, rainfall, and agricultural activity. This study assessed hydrochemistry and soil quality across three locations along the Baro River upper, middle, and lower streams during both dry and wet seasons. Soil samples were collected to assess the impact of irrigation water quality on small-scale irrigation. Water samples were collected and transported in an icebox for laboratory analysis. Two-way ANOVA and one-way ANOVA were employed to evaluate the data. Significant variations in soil properties were observed, with pH ranging from 6.21 to 7.28 across slope positions. The lower slope recorded the highest value in soil organic matter at 3.51%, total nitrogen at 0.22%, available phosphorus (26.08 mg kg−1), and cation exchange capacity (28.88 Cmol (+)/kg). Water quality analysis showed turbidity levels from 54.91 NTU to 90.38 NTU, highest at 109.43 NTU during the wet season. pH values ranged from 7.29 to 7.80, indicating general suitability for irrigation. Electrical conductivity reached a maximum of 2.56 dS/m at the middle location in the wet season, while total dissolved solids were highest at 144.00 mg/L in the lower stream, reflecting increased runoff. Exchangeable bases like calcium (Ca2+) and magnesium (Mg2+) were highest in the lower slope, whereas sodium (Na+) levels were higher in the upper sites. Anion values also revealed that chloride (Cl), bicarbonate (HCO3), and carbonate (CO3) were within suitable FAO ranges, while the Sodium Adsorption Ratio values were also safe for irrigation according to FAO standards. Overall, the water is suitable for agricultural use, but ongoing soil analysis and management practices are crucial for sustainability.