Effects of long-term irrigation practice on soil quality, organic carbon and total nitrogen stocks in the drylands of Ethiopia

Abstract

The study aimed at determining the effects of long-term irrigation practice on soil quality, soil organic carbon (SOC) and total Nitrogen (TN) stocks in the drylands of Ethiopia. Twenty composited and 18 undisturbed soil samples were collected from both irrigated and rain-fed plots at 0–30 cm soil depth. The collected soil samples were analyzed following standard procedures for soil property analysis. Data on soil quality parameters, SOC and TN were subjected to analysis of variance (ANOVA) and principal component analysis (PCA). Finally, soil quality index (SQI) as well as SOC and TN stocks were computed. The experimental results showed significantly higher value for most of the studied soil parameters in irrigated fields compared to the non-irrigated/rain-fed. Long-term irrigation increased SOC and TN stocks by 14.1% and 30%, respectively compared to the field under rain-fed production. A 40.1% increase in SQI was also recorded upon long-term irrigation practice. Overall, the study findings imply that shifting from rain-fed to irrigated production system improves soil quality, SOC and TN stocks in the long-run. For sustained development of the irrigated land use, further research on the impact of other factors such as irrigation method and salinity status of sub-surface soil layers is required.