ABSTRACT
BACKGROUND: Sodic soils are harmful to agricultural and natural environments in Ethiopia's semi-arid and arid regions, leading to soil degradation and reduced productivity. This study investigated how amendment resources could help improve the chemical properties of sodic soils around the Abaya and Chamo Lakes in the South Ethiopia Rift Valley. METHODS: A factorial experiment was conducted to study the effects of gypsum (GYP) and farmyard manure (FYM) on sodic soil reclamation. The experiment had four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha-1), with three replications. The pots were incubated for three months and leached for one month, after which soil samples were collected and analyzed for chemical properties. ANOVA was performed to determine the optimal amendment level for sodic soil reclamation. RESULTS: The study found that applying 10 ton FYM ha-1 and gypsum at 100% gypsum required (GR) rate resulted in a 99.8% decrease in exchangeable sodium percentages (ESP) compared to untreated composite sodic soil and a 1.31% reduction over the control (GYP 0% + FYM 0 ton ha-1). As a result, this leads to a decrease in soil electrical conductivity, exchangeable sodium (Ex. Na), and ESP values. The results were confirmed by the LSD test at 0.05. It is fascinating to see how different treatments can have such a significant impact on soil properties. The prediction models indicate that ESP's sodic soil treatment effect (R2 = 0.95) determines the optimal amendment level for displacing Ex. Na from the exchange site. The best estimator models for ESP using sodic soil treatment levels were ESP = 1.65-0.33 GYP for sole gypsum application and ESP = 1.65-0.33 GYP + 0.28 FYM for combined GYP and FYM application, respectively. CONCLUSION: The study found that combined GYP and FYM applications reduced ESP to less than 10% in agriculture, but further research is needed to determine their effectiveness at the field level.
ABSTRACT
Despite termite-induced soil mixing, summarizing termite-affected soil horizons is difficult, while the lack of accurate information on the pedogenic processes featured by termite bioturbation, topography, and land use limits an effort to address land degradation. A study was therefore carried out to quantitatively classify the soils and describe them based on rangeland uses. Based on cluster analysis, five representative soil profiles were studied at different topographical positions. Soil samples were collected from mounds and adjacent soils under enclosure, cultivated, and open-grazing land at the summit and foot slope positions. Agglomerative clustering showed low Ca2+, CEC, pH, and Mg2+ that described cambic horizons formed Cambisols at the summit and back slope. Eluviation-illuviation processes formed Luvisols on the toe slope and foot slope, whereas clay and high CEC described argic horizons. High Ca2+, CEC, pH, and Mg2+ described calcic horizons that formed Calcisols on the bottom slope. Divisive clustering showed that soil properties varied slightly between Cambisols and Luvisols at different topographies. However, the Luvisols on the toe slope were differentiated from the soil on the foot slope by predominant pedogenetic clay formation and a distinctly increased CEC. Calcisols are placed in other clusters due to their distinct properties. Agglomerative clustering reflected pedogenic processes and differentiated diagnostic horizons, while divisive clustering matched WRB classification. The results of this study also showed that termite-mediated soil properties were dictated by rangeland use, and pedogenesis was more noticeable on open-grazing land than on enclosure or cultivated land.
ABSTRACT
Background: Phosphorus (P) sorption measurements and lime application are of great importance for the sustainable management of P-adsorptive soils. Aim: Therefore, this study aimed to evaluate soil phosphorus sorption under different land-use types and to assess lime input during phosphorus sorption. Treatments include the land use of enclosures, grazing, cultivated and ensut land. Method: Surface soil samples were collected to study the physicochemical properties of specific soils. Lime was mixed with the soils of cultivated land for 30 days. P sorption was subsequently assessed for all land-use types by equilibrating soil samples in 0.01 M CaCl2 containing 30 mL of KH2PO4 at 0, 10, 20, 30, 40, and 50 mg/L. Result: The results showed that land use type had a significant impact on external P demand (EPR). The Langmuir model proved useful information in explaining P sorption. P fixation ranged from 136 to 731.67 mg.kg-1 according to Langmuir model and EPR values ranged from 45.9 to 398.7 mg P kg-1 soil. Exclusory area soil has high sorption compared to other land-use whereas enset land-uses the lowest sorption. The result of correlation analysis revealed that exchangeable Aluminium and clay had positively correlated on P-sorption maximum and SPR of both models. Conclusion: It was concluded that there was a significant difference among land-use systems of P-sorption and there had an influence of lime on acidic soil to reduce EPR. So black market p-fertilizer utilization is not recommended to study site. Liming also restored the soil chemistry of cultivated land. Nevertheless, field trials were proposed to validate mineralization rates and EPR values in cultivated soils.
