Effects of Different Cropping and Land Management Practices on the Quality of Irrigated Soils of the Upper Awash Basin, Central Rift Valley of Ethiopia

Irrigation is one way of utilizing the land resources to enhance agricultural production. Irrigation crop production is crucial in the present study area due to its arid and semi-arid climatic characteristics. However, little is known about the influence of different cropping and land management practices on soil quality (SQ). This study aimed to determine the effects of different cropping systems and land management practices on variability of SQ indicators in the Central Rift Valley of Ethiopia (CRVE). To this end, 45 disturbed surface (0‒20 cm) and 24 undisturbed (upper 7 cm) soil samples were collected from four adjacent farms: large-scale perennial farms (LSPF), large-scale annual farms (LSAF), smallholder subsistence annual farms (SHAF), and non-cultivated lands (NCL). Soil analyses were made for selected SQ indicators – particle size analysis, bulk density, soil water content, organic matter, pH, total nitrogen, available potassium and phosphorus, exchangeable bases, and cation exchange capacity. One-way analysis of variance (ANOVA) and Pearson correlation coefficient (r) were computed. Key informants’ interview was conducted to substantiate the data obtained from soil laboratory analyses. As the results confirmed, different cropping and land management practices had significant effects on some SQ indicators. Soil organic matter, total nitrogen, available P, and available K declined significantly (P < 0.05) in the soils of LSAF and SHAF. This is attributed to land management-induced problems such as frequent tillage practice of mono-cropping, high level of mechanization, removal of crop residues/above-ground biomass in LSAF, and use of low external inputs and overcultivation without appropriate land management practices in SHAF. However, LSPF practice resulted in the improvement of key SQ indicators, next to NCL. Therefore, LSPF can be an alternative cropping and land management practice to achieve sustainable agricultural production and land management in semi-arid irrigated lands of CRVE and in places with similar environments.