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Background: Land degradation reduces agricultural productivity and poses a serious threat on food security status of households. In Ethiopia, farmers have been using only urea and di-ammonium phosphate for more than 15 years. Several reports that indicate lack of response to these fertilizers, which could be due to limitation of nutrients other than nitrogen and phosphorus. Therefore, the present study was initiated to evaluate the soil fertility status of ten sites in central highlands Vertisols of Ethiopia and wheat nutrient content. Results:The physico-chemical properties of soils showed that the soils were clayey in texture, neutral to slightly alkaline (pH 7.2-7.9) and low to medium in their organic matter (1.6-3.2 %) content. Total N content was low in 100 % of the samples while 80 % of the soil samples showed P deficiency (<10 mg kg −1 ). Exchangeable K, Ca and Mg in all soil samples were high, while available sulfur was low. On the other hand, K to Mg ratio varied from 0.13:1 to 0.44:1, indicating Mg induced K deficiency. All soil samples were adequate when analyzed by ammonium bicarbonate diethylene tri-amine penta-acetic acid extractable Cu (>0.5 mg kg ) and acid ammonium oxalate extractable Mo (<0.1 mg kg −1 ) were found to be low in all soil samples. The plant analysis data showed that all samples were low in N, P and K, while high in Ca and Mg concentrations. The deficiency of tissue K content was not predicted by the soil exchangeable K test. Plant micronutrient analysis showed that Cu, Fe, Mn and Cl concentrations were within the sufficiency range while Zn was deficient in all of the samples. Conclusions:Soil and/or tissue test results are indicative of deficiency of N, P, K, S, Zn, B and Mo that could be amended by fertilizer application, although more data are needed to thoroughly support this conclusion. The highest correlation (r > 0.90) between soil and plant nutrient content was observed for P, K, Mg, Cu, Fe, Mn and Zn, implying that flag leaves at flowering stage can be used to calibrate soil and plant contents for the deficient nutrients.

Background: Understanding the landscape features of agricultural lands and soil management practices is pertinent to verify the potential and limitations of the soil resources; and devise relevant land management strategies. However, information is lacking in Wolaita, Southern Ethiopia. Thus, this study aimed at investigating the physiographic characteristics of agricultural lands, farmers' soil fertility management practices and their influences on soil fertility and crop productivity was conducted. The survey involved 789 randomly sampled agricultural lands. Soil sample as well as data on slope, topography, land use, crop rotation, fallowing, cropping intensity, crop residue management, fertilizer use and farmers' estimated crop yield were collected and evaluated. Results:The result indicated that agriculture has been practiced under diverse slope positions (1-58%). This significantly influenced most of soil physico-chemical properties in which an increase in soil bulk density, and decrease in available phosphorous, exchangeable calcium, extractable boron, copper, iron and zinc with an increase in slope positions were recorded. Furthermore, continuous cultivation without any fallow periods and complete crop residue removal (96%) were common practices. Fertilizer use was not sufficient. The average use (kg ha −1 ) was 30 and 9 for diammonium phosphate (DAP) and urea, respectively, and about 89% of study area received manure below 1.5 t ha −1 . All these limitations made farmers to experience lower crop yield than the national average estimates. Conclusion:Based on the result, it is possible to conclude that the following soil management interventions such as soil conservation, application of sufficient organic and inorganic fertilizers are recommended to restore the soil fertility and improve crop productivity.

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Background: Wastewater irrigation for vegetable production is a highly prevalent practice in Addis Ababa and a number of articles have been published on wastewater-irrigated soils and vegetables contaminated with heavy metals. However, to the best of our knowledge, an insight into assessment of human health risks associated with the consumption of vegetable crops grown on wastewater-irrigated soils is non-existent in the city. Long-term effect of wastewater irrigation on the build-up of heavy metals in soils and selected vegetable crops in Addis Ababa urban vegetable farming sites (10) was evaluated. By calculating estimated daily intakes (EDIs) and target hazard quotients (THQs) of metals, health risk associated with the consumption of the analyzed vegetables was also evaluated. Results: The heavy metal concentrations in irrigation water and soils did not exceed the recommended maximum limits (RMLs). Moreover, Cd, Co, Cr, Cu, Ni and Zn concentrations in all analyzed vegetables were lower than the RML standards. In contrast, Pb concentrations were 1.4-3.9 times higher. Results of two way ANOVA test showed that variation in metals concentrations were significant (p < 0.001) across farming site, vegetable type and site x vegetable interaction. The EDI and THQ values showed that there would be no potential health risk to local inhabitants due to intake of individual metal if one or more of the analyzed vegetables are consumed. Furthermore, total target hazard quotients (TTHQs) for the combined metals due to all analyzed vegetables were lower than 1, suggesting no potential health risk even to highly exposed local inhabitants. Conclusions: There is a great respite that toxic metals like Pb and Cd have not posed potential health risk even after long term (more than 50 years) use of this water for irrigation. However, intermittent monitoring of the metals from irrigation water, in soil and crops may be required to follow/prevent their build-up in the food chain.

A study was conducted in the Tsegede highlands of Tigray Region, northern Ethiopia to determine the changes in some physical and chemical attributes across three adjacent acidic soil sites with different elevation and three land use types. Analytical results of the collected surface layer soil samples showed significant (P  0.05) correlation of soil bulk density, OM and total N with elevation. In the lower elevation site (Indaslasie), soil OM content declined by about 43 and 52% compared with that of the two higher elevation sites (Cheguarcudo and Indamariam), respectively. Soil pH, exchangeable acidity, exchangeable Al, OM, total N and available phosphorus also exhibited significant (P  0.05) disparity across the three land use types of the area. Soils of the forest land were less acidic by 0.43 and 0.68 pH units than the cultivated and grazing lands, respectively. The soil OM content of the cultivated land was significantly lower by about 25 and 35% than the grazing and forest land soils, respectively. Available soil P status was low and showed significant correlations with pH (r = 0.65**), exchangeable acidity (r = −0.58*) and Al (r = −0.53*). In general, the study results revealed altitude did not impose any significant effect in aggravating soil acidity whereas land use type affected significantly not only soil acidity but also the important soil fertility related parameters such as OM, total N and available P contents. Therefore, it can be suggested that besides to the usual acid soil management and/or reclamation practices, introducing proper land use management systems are of paramount importance.

The yield of grain sorghum (Sorghum bicolor L. Moench) and other crops is often constrained by soil water deficits in semiarid areas of Ethiopia. The effectiveness of micro‐basin tillage, in the form of tied‐ridging, was evaluated as a means of improving soil water availability through reduced runoff and to increase grain and stover yield. Field research was conducted on a clay soil with vertic properties (Typic Pellustert) in northern Ethiopia in 2003 and 2004. Tied‐ridging conducted before planting, at planting, and after planting was compared with planting on a flat soil surface without ridging and with a traditional ridging practice known as shilshalo Planting in‐furrow was compared with planting on‐ridge. Tied‐ridging before or at planting resulted in the best soil water status throughout the season and the best crop performance, especially when planting was in‐furrow. Mean soil water content with the most effective tied‐ridge treatment was on average 42% and 49% more than with flat tillage and planting in 2003 and 2004, respectively. Overall crop performance was generally worst for flat soil surface planting and for the shilshalo treatment, where the respective grain yield was 45% and 62% of yield with in‐furrow planting, respectively. Soil water availability in the 0‐ to 0.90‐m soil depth dropped below the permanent wilting point for all treatments before the grain was physiologically mature. Yield can be increased by tied‐ridging before or at planting. The results indicate that mean yield can be improved by planting with the onset of the rains.

Background: In Addis Ababa, where irrigation water for vegetable production is commonly derived from the highly polluted Akaki river, information on microbial contamination of water and irrigated vegetable is scanty. An assessment was done to determine the microbiological quality of irrigation water and lettuce harvested from 10 urban farming sites of Addis Ababa. The efficacy of 5 lettuce washing methods were also assessed. A total of 210 lettuce and 90 irrigation water samples were analyzed for faecal coliform and helminth eggs population levels. Results: The mean faecal coliform levels of irrigation water ranged from 4.29-5.61 log 10 MPN 100 ml −1 , while on lettuce, the concentrations ranged from 3.46-5.03 log 10 MPN 100 g