Browsing by Author "Rwehumbiza, F. B. R"

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Phosphorus Adsorption Isotherm: A Key Aspect for Soil Phosphorus Fertility Management
(Science Domain, 2014) Wogi, Lemma; Msaky, J. J; Rwehumbiza, F. B. R; Kibebew, Kibret
Characterization of soils in terms of phosphorus adsorption capacity is fundamental for effective soil phosphorus fertility management and for efficient utilization of phosphorus fertilizers. Thus, this study was conducted to investigate the phosphorus adsorption characteristics of soils of two farms and to elucidate the implication of soil phosphorus adsorption isotherm studies for soil phosphorus fertility management. The two farms, representing the major farming systems of the respective districts, were selected from Adele village in Haramaya district and Bala Langey village in Kersa district in eastern Ethiopia. Soil samples were collected from the crop fields at Adele and Bala Langey farms. Two different P-bearing sources, potassium dihydrogen phosphate (KH2PO4) and diammonium phosphate (DAP-(NH4)2HPO4), were used for the adsorption isotherm studies. The adsorption data were fitted to the linear and Freundlich adsorption isotherm models. Both models revealed that soils of both farms had different P adsorption capacity from the two P sources. Amount of P adsorbed from DAP solution was higher than the amount of P adsorbed from KH2PO4 solution in soils of both farms. Phosphorus adsorption capacity of Adele farm soils was higher than that of Bala Langey farm soils. Therefore, soils of the two farms should be managed differently for P fertility. Percentages of P adsorbed (% Pa) and P remained in the equilibrium solution (% EC) were also calculated. By plotting the two percentages i.e. % Pa and % EC against the initial concentration of P (IC), two regions were observed. The two regions were described as P intensity and quantity factor windows. Based on the intensity and quantity factor windows, at currently existing soil condition, between 200 and 500 kgha-1 P should be applied as fertilizer to soils of Adele at 0-30 cm depth for immediate benefits and soil P fertility maintenance.
Spatial Distribution of Organic Carbon and Nutrients under Farmers’ Crop Residue Management Practices in Eastern Ethiopia
(Science Domain, 2015) Wogi, Lemma; Msaky, J. J; Rwehumbiza, F. B. R; Kibret, Kibebew
Understanding the distribution and transport of organic carbon and nutrients under any management in a farming system is vital for predicting the sustainability of a farming system. This study was conducted to characterize the spatial distribution and transport of organic carbon and nutrients under farmer’s crop residues management involving complete removal of the residues and to identify which nutrients are highly affected by such management practices. Two farms, representing the major farming systems of the study areas, were selected from Adele and Bala Langey villages in Haramaya and Kersa districts, respectively in Eastern Ethiopia. Soil samples were collected along the slope gradient from the crop fields and at a given distance from home in homesteads of each farm at a depth of 0 – 30 cm. The samples were analyzed following standard methods for soil organic carbon and nutrient contents. Results indicated that distributions of organic carbon and nutrients were affected by slope gradients in crop fields and by distances in homesteads at both farms. Results showed that 2.95 and 2.15% OC, 0.52 and 0.25% N, 100.15 and 41.23 mgkg-1 available P, and 25.05 and 1.65 mgkg-1 extractable S were accumulated near homes of the households at Adele and Bala Langey farms, respectively. Quantities of OC, N, P, and S were less than 2%, 0.15%, 25 mgkg-1 and 2 mgkg-1, respectively in the crop fields at both farms. Amounts of N transported from Adele and Bala Langey crop fields through haricot bean residue were 4.70 and 5.60 g/kg dry matter, respectively. The extent of crop residue removal management effects on the distribution of the nutrients, from the most to the least affected, follows the order P > OC > S > N > exchangeable bases > micronutrients at both farms. Intervention management should focus on reversing the flow of organic carbon and nutrients from crop fields to the homesteads and minimizing unequal distribution of organic carbon and nutrients in the farming system at both farms
Status of Selected Properties of Soils under Crop Livestock Farming System in Eastern Ethiopia
(Science Domain, 2014) Wogi, Lemma; Msaky, J. J; Rwehumbiza, F. B. R; Kibret, Kibebew
nformation on soil properties and fertility status of soils at farm levels under particular farming system is essential for boosting farm productivity and for sufficient food production. This study was conducted to investigate status and properties of soils under crop-livestock farming system, where crop grains are produced for food security and residues for animal feed and domestic fuel consumption. For the study, two farms under similar farming system were selected from two districts in eastern part of Ethiopia: Adele farm from Haramaya and Bala Langey farm from Kersa districts. Soil samples were collected from crop fields of each farm and analyzed following standard methods for soil physical and chemical analyses. The results indicate that soil textural class is sandy clay loam at both farms. The mean bulk density values were 1.43 and 1.39g cm-3 for Adele and Bala Langey farms, respectively. The soil reaction for Adele farm was neutral (pH=7.23) whereas soils of Bala Langey farm had slightly acidic reaction (pH=6.57). Organic carbon contents of soils of both farms were low, less than 1.5%. Nitrogen was low for Adele farm soils (<0.15%) and in the moderate range for Bala Langey farm soils (0.15-0.25%). Available soil P was very low at both farms (<10mgkg-1 ). Extractable soil sulfur was also low for both farms (<5 mgkg1 ). CEC of the soils of Adele farm was very high (>50Cmol (+)kg-1 ) and it was high (>40 Cmol(+)kg-1) for Bala Langey farm soils. Exchangeable base contents and EDTA extractable micronutrients were in the sufficiency ranges for soils of both farms. This study indicated that very low available phosphorus, low organic carbon and nitrogen followed by sulfur are the most productivity limiting factors associated with soil fertility as a result of crop residues removal for animal feed and domestic fuel consumption. Intervention management should focus on the enhancement of organic carbon, phosphorus, nitrogen and sulfur.