Inter-structural Space Effect of Fanya juu and Soil Bund Soil and Water Conservation Structures on Selected Soil Properties: In the Case of Habru District, North Ethiopia

Abstract

Land degradation is one of the most serious environmental problems in Ethiopia. To halt the problem, large scale soil and water conservation (SWC) practices such as; fanya juu, soil bund and other physical structures were implemented in the different parts of the country including Habru district. However, development of fertility gradient between the two successive SWC structures makes debatable to use the implemented structures in the sustainable manner. The study aimed at evaluating the spatial variability in soil properties between inter-structuralterrace area. Representative Kutaye catchment was deliberately selected based on the availability of fanya juu and soil bund. Then the catchment was subdivided into two sub-watersheds, cropland treated with fanya juu and cropland treated with soil bund based on the structural dominance. Inter-structure-terrace plots were independently selected and systematically replicated (second, fourth and sixth) between two SWC structures for the purpose of soil sampling. In order to evaluate selected soil property variation, the soil samples were taken following the contour between the two successive structures. Additionally, undisturbed core samples were collected for the bulk density analysis. The samples were analyzed following standard laboratory procedure and parameters like; soil texture, bulk density (Bd), soil reaction (pH), organic carbon (OC), total nitrogen (TotN) available phosphorus (AvP), cation exchange capacity (CEC), exchangeable potassium (K+) and electrical conductivity (EC) were determined. Statistical analysis was performed using SPSS v.20 software. Parameter relative distance was created for allowing comparison; because the distance between the successive SWC structures were highly variable. Oneway ANOVA was used; selected soil properties as dependent and relative distance (inter-structure area) as independent variables. Tukey (HSD test) was used for mean separation between relative distance at p < 0.05. The result revealed that soil properties percentage of sand and clay significantly influenced by inter-structure-spaces plots treated with fanya juu at p < 0.05. In both SWC structures, cation exchange capacity (CEC), exchangeable potassium (K+) and bulk density (Bd) were significantly (p < 0.05) affected with inter-structure space. In order to manage variation in some soil properties between the successive SWC inter-structures-space area; optimizing its' inter-structural terrace space and application of site-specific soil management practices were suggested with appropriate contour ploughing.