Browsing by Author "AZMERA WALCHE MENGESHA"

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    CHARACTERIZATION, MAPPING, AND EVALUATION OF RECLAMATION RESOURCES FOR SOILS AROUND ABAYA AND CHAMO LAKES, SOUTHERN ETHIOPIAN RIFT VALLEY
    (Hawassa University College of Agriculture, 2024) AZMERA WALCHE MENGESHA
    Characterizing and understanding the nature of the soil and its management are crucial for successful crop production. With this in mind, experiments were conducted to (1) characterize of soils surrounding Lakes Abaya and Chamo, (2) analyze nutrient contents and map the fertility status of agricultural soils, (3) determine the intensity and types of soils and map their spatial distribution patterns, and (4) investigate the efficacy of gypsum and farmyard manure and their combined application in reclaiming sodic soil's chemical and physical properties. The first study revealed that the soil properties in the study site were highly heterogeneous in terms of morphological, physical, and chemical characteristics. Most of the studied soils were highly alkaline (>8.5), had very high sodium content (>20 cmolc kg-1 ), very high CEC value (> 40 cmolc kg-1 ), very low TN (<0.1%), and low levels of organic carbon (0.5-1.5%) and exchangeable calcium (2-5 cmolc kg-1 ). The study recommended removing sodium and salts from the soil depth to improve the productivity of agricultural soils in the area. Applying organic amendments such as manures and crop residues was also suggested to increase fertility and organic matter content. The second study showed the soil texture in the area was mainly clay, heavy clay (Ganta Kanchama site), and sandy clay loam. The surface soil had a higher available water holding capacity than the subsurface depth, indicating more plant water storing space. The soils in the studied area had an alkaline pH, moderately (2-4 dSm-1 ) to highly saline (4-8 dSm-1 ) EC values, high exchangeable sodium percentage (50-70%), high soil CEC, low OC, very low total nitrogen content, high potassium availability (>300 mg kg-1 ), and xxiii lower calcium carbonate content. The study showed the soils of the area were fertile, however, incorporating organic matter into the soil enhances its structure, water retention, and nutrient availability, reducing salinity and sodicity. The results of the third experiment revealed that the study area has moderately (7.9-8.4) to strongly alkaline soil pH (8.5-9.0), slightly (0.75-2 dS m-1 ) to moderately saline (2-4 dS m-1 ) EC values, and a high variability in soil ESP values, indicating a strong variability in soil sodicity across different parts of the study area. Out of 2274.65 ha of the studied area, 62.28%, 26.09%, 10.99%, and 0.63% were categorized as nonsaline non-sodic, saline-sodic, sodic, and saline, respectively. The results showed that almost all salt-affected sites were situated in relatively low-lying slope (0-2 %) areas, flat to almost flat slopes. The findings suggest that the place needs specific soil management strategies to address the salinity and sodicity problems. The last study investigated the impact of amendment resources on sodic soils. A pot experiment consisting of a factorial combination of four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha−1 ), with Complete Randomized Design (CRD and three replications was used. The results showed that applying gypsum (GYP) and farmyard manure (FYM) reduced exchangeable sodium percentage (ESP) in sodic soils. Specifically, using 10 ton FYM ha-1 and GYP at 100% GYP required (GR) rate resulted in a 99.8% decrease in ESP compared to untreated composite sodic soil. The study also indicated optimal amendment levels (combined application of 100% GYP and 10 ton FYM ha-1 ) for displacing exchangeable sodium from the exchange site using prediction models. Agglomerative hierarchical and K-means cluster analysis suggest that treatment levels and reclaimed soils with similar properties require application of comparable treatment levels and similar management. The study found that combined applications of GYP (at 100% gypsum requirement rate) and FYM (10 ton FYM ha-1 ) reduced ESP to less than 10% in agricultural soil. However, further research is needed to determine their effectiveness at the field level.