Kibebew Kibret

Soil–Plant Nutrient Status and their Relations in Maize-Growing Fields of Wolaita Zone, Southern Ethiopia

ABSTRACT This study investigates the soil–plant nutrient status and relationship in Wolaita, Southern Ethiopia. Maize leaves, soil samples and field history were collected. The result indicated that continuous cultivation without fallowing, complete crop residue removal and inadequate fertilization were common practices. The soil was low in organic carbon, total nitrogen, available phosphorus, potassium, sulfur, boron and copper. Tissue analysis indicated 100, 84, 54 and 28% deficiency of nitrogen, phosphorus, potassium and copper, respectively. Significant and positive correlations (r = 0.70, 0.40 and 0.50) of soil phosphorus, calcium and copper with tissue content were observed. Soil pH was correlated with tissue phosphorus (r = 0.4), iron (r =—0.3) and manganese (r = −0.7). Overall, the levels of calcium, magnesium, iron, manganese and zinc were adequate for maize. Therefore, fertilizer application addressing nitrogen, phosphorus, potassium and copper deficiencies is recommended for the study area.

Soil-Landscape Modeling and Remote Sensing to Provide Spatial Representation of Soil Attributes for an Ethiopian Watershed

Information about the spatial distribution of soil properties is necessary for natural resources modeling; however, the cost of soil surveys limits the development of high-resolution soil maps. The objective of this study was to provide an approach for predicting soil attributes. Topographic attributes and the normalized difference vegetation index (NDVI) were used to provide information about the spatial distribution of soil properties using clustering and statistical techniques for the 56 km2 Gumara-Maksegnit watershed in Ethiopia. Multiple linear regression models implemented within classified subwatersheds explained 6–85% of the variations in soil depth, texture, organic matter, bulk density, pH, total nitrogen, available phosphorous, and stone content. The prediction model was favorably comparable with the interpolation using the inverse distance weighted algorithm. The use of satellite images improved the prediction. The soil depth prediction accuracy dropped gradually from 98% when 180 field observations were used to 65% using only 25 field observations. Soil attributes were predicted with acceptable accuracy even with a low density of observations (1-2 observations/2 km2). This is because the model utilizes topographic and satellite data to support the statistical prediction of soil properties between two observations. Hence, the use of DEM and remote sensing with minimum field data provides an alternative source of spatially continuous soil attributes.

Effects of Lime, Vermicompost, and Chemical P Fertilizer on Selected Properties of Acid Soils of Ebantu District, Western Highlands of Ethiopia

Soil acidity is one of the major factors limiting soil fertility and crop production in large areas of Ethiopia. A two-month incubation experiment was conducted to evaluate the effects of lime, vermicompost (VC), and chemical phosphorus (P) fertilizer on selected chemical properties of Dystric Nitisols in Ebantu District, Western Ethiopia. The treatments comprised of three rates of lime (2, 4, and 6 tons CaCO3·ha−1), VC (2.5, 5, and 7.5 tons·ha−1), and mineral P fertilizer (20, 40, and 60 kg·P·ha−1) each applied alone and in various combinations. The experiment was laid down in a completely randomized design with two replications. The results showed that the highest increment of pH from 4.83 at the control to 6.05 and reduction of exchangeable Al from 1.70 to 0.09 cmolc·kg−1 were obtained from combined application of lime at 4 tons CaCO3·ha−1 and VC at 7.5 tons·ha−1. The most significant decrease in exchangeable acidity (0.17 cmolc.kg-1) was observed in soil that was treated with 6 tons CaCO3·ha−1 lime applied alone (93%) and combined application of lime at 4 tons CaCO3·ha−1 with VC at 7.5 tons·ha−1 by (81%). The highest contents of OM (4.1%) and total nitrogen (0.29%) were obtained from combined application of lime at 4 tons CaCO3·ha−1 and VC at 7.5 tons·ha−1. Integrated application of chemical P (60 kg·P·ha−1) with lime (2 tons·ha−1) plus VC (7.5 tons·ha−1) resulted in Bray-II P increased by 45% relative to control. The various combinations of the treatments also improved exchangeable Ca2+ and Mg2+. The results indicate that integrated use of lime, vermicompost, and chemical P fertilizer can improve soil acidity and availability of nutrients. However, the real potential of the amendments used in this experiment should be further assessed under field conditions using a test crop.

Physical Land Suitability Evaluation for Irrigation in the Lower Alwero River Area of Abobo, Western Ethiopia

Land suitability assessment plays an important role in identifying biophysical constraints and evaluating potential capacity of land and its sustainable use. Physical land suitability evaluation for irrigation was carried out in the lower Alwero river area of Abobo, western Ethiopia, following FAO methodology for general irrigation farming. The irrigation suitability of five land mapping units (LMUs): 1Ac, 1Bc, 1Ecl, 2Cc and 3Ccl were assessed by considering slope, drainage, top soil texture, sub soil texture, surface stoniness, surface coarse fragments, subsurface coarse fragment, rockiness, depth to solid rock or hardpan, lime, gypsum, electrical conductivity (EC) and exchangeable sodium percentage (ESP). The result revealed that LMU 1Ac, 1Bc and 2Cc, with total area of 22,367.9 ha (83.7%), were moderately suitable (S2). The moderate limiting factors were drainage, top soil texture and subsoil texture. On the other hand, LMU 1Ec1, covering an area of 3,677.6 ha (13.8%) was not suitable (N) for irrigation due to subsurface coarse fragments and depth to solid rock or hardpan. For all LMUs, parameters like lime, gypsum, EC and ESP were not considered as limiting factors.

Assessment of Soil Fertility Status at Dawja Watershed in Enebse Sar Midir District, Northwestern Ethiopia

Information on soil fertility status is key in predicting the relative response of soils to fertilizer application and adopting appropriate management practices. The present study was conducted to assess the fertility status of the soils of the Dawja Watershed in Enebse Sar Midir District. 21 composite soil samples were collected from the 0-20 cm soil depth of 7 land units, identified based on their slope and management practices. Except available phosphorus, all the soil parameters were significantly ( P < 0.05) affected by differences in land units. The textural class of the soils varied between sandy clay loam and sandy clay. The bulk density of the soils under the different land units ranged between 1.32 and 1.41 g cm -3 and the total porosity varied from 46.66 to 50.10%. The pH of the soils ranged from 5.7 to 6.8. The organic matter content of the soils was generally low and ranged between 1.17% in cultivated land unit to 2.46% in grazing land unit soils. The total nitrogen content of the soils ranged from 0.13 to 0.19%. Available P (Olsen) was generally high in all the land units and ranged between 17.92 to 23.02 mg kg -1 . The results further showed that the

Status of Selected Properties of Soils under Crop- Livestock Farming System in Eastern Ethiopia

Information 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

Phosphorus adsorption isotherm: a key aspect for soil phosphorus fertility management.

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 Original Research Article Wogi et al.; AJEA, 6(2): 74-82, 2015; Article no.AJEA.2015.066 75 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.