66 research outputs found
Spatial assessment of land degradation through key ecosystem services: The role of globally available data
No full textLand degradation is a serious issue especially in dry and developing countries leading to ecosystem services (ESS) degradation due to soil functions' depletion. Reliably mapping land degradation spatial distribution is therefore important for policy decisions. The main objectives of this paper were to infer land degradation through ESS assessment and compare the modelling results obtained using different sets of data. We modelled important physical processes (sediment erosion and nutrient export) and the equivalent ecosystem services (sediment and nutrient retention) to infer land degradation in an area in the Ethiopian Great Rift Valley. To model soil erosion/retention capability, and nitrogen export/retention capability, two datasets were used: a ‘global’ dataset derived from existing global-coverage data and a hybrid dataset where global data were integrated with data from local surveys. The results showed that ESS assessments can be used to infer land degradation and identify priority areas for interventions. The comparison between the modelling results of the two different input datasets showed that caution is necessary if only global-coverage data are used at a local scale. In remote and data-poor areas, an approach that integrates global data with targeted local sampling campaigns might be a good compromise to use ecosystem services in decision-making
Response of maize yield to nitrogen, phosphorus, potassium and sulphur rates on Andosols and Nitisols in Ethiopia
No full textThe use of fertilizers in balanced and adequate amounts is a prerequisite for increasing crop productivity and production. Unbalanced plant nutrient management continues to be a major factor contributing to low maize (Zea mays L.) yields due to lack of information on the dose–responses to macronutrients on different soil types in Ethiopia. This study was carried out to quantify maize yield response and agronomic efficiency of varying application rates of nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) under balanced application of other nutrients across two soil types in Ethiopia. Field trials were set up on 29 farmers’ fields in four districts of Oromia and Southern Nations, Nationalities and Peoples Region (SNNPR) for three consecutive cropping seasons (2014–2017). The treatments consisted of six rates of N, P and S each and eight rates of K combined with balanced application of the remaining macronutrients, zinc (Zn) and boron (B). The treatments were laid out in randomised complete blocks design with three replicates per farm. Using nutrient dose–response modelling, the agronomic optimum rates of N, P, K and S were estimated at 46, 40, 17 and 10 kg ha−1 on Nitisols, with balanced application of the other nutrients. On Andosols, the optimum rates of N, P and S were estimated at 184, 20 and 30 kg ha−1, respectively, but the optimum K rate could not be estimated. The predicted maximum yields obtained with balanced nutrient application were lower on Andosols (3397–3640 kg ha−1) than on Nitisols (4630–6094 kg ha−1). Using the Mitscherlich dose–response model, the percentage deficiencies of N, P, K and S were estimated to be 1.3–3.3 times more on Nitisols than Andosols. Consequently, agronomic efficiencies of N, P, K and S were significantly lower on Andosols than on Nitisols. It is concluded that balanced application of 46 kg N ha−1 , 40 kg P ha−1 , 17 kg K ha−1 , 10 kg ha−1 S, 2 kg Zn ha−1 and 0.5 kg B ha−1 could be recommended for maize on Nitisols in the study area. Although this recommendation may also apply to Andosol, further research is needed as the productivity of Andosols appears to be limited by constrains other than N, P, K, S, Zn and B. We also recommend a shift from the blanket fertilizer recommendations to site-specific nutrient management based on good understanding of the variations in crop response with soil type and agroecology and appropriate soil and plant analyses
Macro and Micro Nutrients for Optimizing Maize Production at Hawassa Zuria District, Southern Ethiopia
No full textLack of practical information on the use of multi-nutrient fertilizer blends involving the actual limiting nutrients for specific site and crop is a problem for sustainable maize production. A trial was conduct to evaluate different fertilizer types for maize production in Southern Ethiopia during the main cropping season of 2016 and 2017. Fertilizer treatments were based on limiting nutrients of the area including NPS, NPSB and NPSBCu at different rate. The trial consists of ten treatments (1) no fertilizer (control) (2) NPS: 69 kg N + 23.5 kg P + 10 kg S/ha (3) NPS: 92 kg N + 31.3 kg P + 13 kg S/ha (4) NPS: 115 kg N + 39 kg P + 17 kg S/ha (5) NPSB: 69 kg N + 23.5 kg P + 10 kg S + 1.07 kg B/ha (6) NPSB: 92 kg N + 31.3 kg P + 13 kg S + 1.4 kg B/ha (7) NPSB: 115 kg N + 39 kg P + 17 kg S + 1.7 kg B/ha (8) NPSBCu: 69 kg N + 23.5 kg P + 10 kg S + 1.07 kg B + 0.625 kg Cu/ha (9) NPSBCu: 92 kg N 31.3 kg P + 13 kg S + 1.4 kg B + 0.625 kg Cu/ha and (10) NPSBCu:115 kg N + 39 kg P + 17 kg S + 1.7 kg B + 0.625 kg Cu/ha. The trial was conducted on two farms and treatments were laid out in a randomized complete block design replicated three times in each farm. Crop characteristics measured were analyzed using Proc GLM procedures in the SAS 9.3 program. Economic analysis was also performed to investigate the economic feasibility of the fertilizers for maize production. Applying the deficient soil nutrients, nitrogen, phosphorus, sulphur and boron was improved maize yield. Treatment 7 (NPSB: 115, 90, 17, 1.7) gave significantly (P < 0.05) higher maize yield compared to some fertilizer treatments and the control. Similarly, highest net benefit (31962.2 Ethiopia birr/ha) was obtained from treatment 7 with acceptable marginal rate of return (224%). Therefore, NPSB in the nutrient ratio of 115: 90: 17: 1.7 is recommended as the best option for maize producers around H/zuria district. Keywords: macro and micronutrient, maize yield, fertilizer types, economic feasibilit
Soil Phosphorus Fractions as Influenced by Different Cropping Systems: Direct and Indirect Effects of Soil properties on Different P Pools of Nitisols of Wolayta, Ethiopia
No full textData from 12 surface soils (0 – 15 cm depth)of three cropping systems (enset, maize and grazing land) and path analysis was used to evaluate effects of soil properties: pH, texture (Clay, silt and sand) , organic carbon (OC) cation exchange capacity (CEC),citrate-dithionite-bicarbonate (CDB) extractable Fe and Al (Fed and Ald) on total phosphorous (Pt), organic phosphorous (Po), Olsen P (Available P) and Chang and Jackson (1957) inorganic phosphorous (Pi) fractions. Correlation analysis was performed to study the relationships between soil properties and different soil P pools while path analysis model was used to evaluate direct and indirect effect of these soil properties on the P pools. Only soil properties that significantly contribute to the fit of the model were used. High significant values of coefficient of determination (R2) and low values of uncorrelated residual (U) values indicate the path analysis model explains most of the variations in soil Pt, Po, Olsen-P, Saloid-P, Ca-P, Al-P, and Fe-P pools. Soil pH had significantly high and positive direct effect (D = 0.618*) on Pt, (D = 1.044***) on saloid P, and (D = 1.109***) on Fe-P with modest and negative indirect effect (D= -0.478 and -0.405) on saloid P and Fe-P, respectively, through OC. The direct effect of clay on Ca-P, Al-P and Fe-P (readily available P forms) was significant and negative with a relatively higher indirect effect on Fe-P through pH suggesting that clay is dominant soil property that influences readily available P pools in Nitisols of the study area. Fed had significant and negative direct effect (D = -0.430*) on Olsen available P with low negative indirect effect ( D = -0.154) through pH results in significant and negative correlation (r = -0.657*). The significant and negative direct effect of Fed on Olsen P indicates that crystalline iron is the sink for available P. Relative influence of the soil properties on the soil P pools was in the order: pH > clay > Fed > OC. These results show that most of P pools of Nitisols of Wolayita are best predicted from pH, clay (texture), Fed and OC. On the other hand, our data also show that the inclusion of other soil variables is needed to fully predict Ca-P and stable P pools
Effect of Different Blended Fertilizers Formulae for the Productivity of Sesame at Bench Maji Zone, South Ethiopia
No full textSesame productivity in our country Ethiopia is low due to unbalanced fertilization and soil fertility degradation beyond disease and lacking using an improved variety of sesame. The experiment was conducted for two growing seasons to identify the effects of different blended fertilizer formulae applications on sesame yield and yield components at Menit Goldia. The treatments are control, nitrogen, phosphorus, sulfur and boron (NPSB) formula 1 = 46 kg.ha-1 N, 54 kg.ha-1 P,10 kg.ha-1 S, and 1.07 kg.ha-1 B; formulae 2 = 69 kg.ha-1 N,72 kg.ha-1 P,13 kg.ha-1 S, and 1.4 kg.ha-1 B, formula 3 = 92 kg.ha-1 N, 90 kg.ha-1 P, 17 kg.ha-1 S, and 1.7 kg.ha-1 B. The experiment was arranged in a randomized complete block design with three replications. The application NPSB formula resulted in the highest sesame yield and yield component as compared to the control. The economic analysis demonstrated that the maximum net benefit with the highest marginal rate of return was obtained due to the application of formula 3 as compared to control, therefore formula 3 is recommended to grow sesame at Menit Goldia and other areas with similar environment
On mapping problems in several complex variables
No full textThe thesis consists of two parts. In the first part, we study a regularity problem for CR mappings between CR manifolds. More precisely, we establish various versions of the Schwarz reflection principle in several complex variables. In particular, as a consequence of the main results, we confirm a conjecture of X. Huang in [Hu2] and provide a solution to a question raised by Forstneric [Fr1] (See Corollaries 2.1.11 and 2.1.12). It is a joint work with Shiferaw Berhanu ([BX1], [BX2]). In the second part, we study the embeddability problem from compact real algebraic strongly pseudoconvex hypersurfaces into a sphere. In a joint work with Xiaojun Huang and Xiaoshan Li ([HLX]), we prove that for any integer there is a family of compact real algebraic strongly pseudoconvex hypersurfaces in none of which can be locally holomorphically embedded into the unit sphere in This shows that the Whitney (or Remmert, respectively) type embedding theorem in differential topology (or in the Stein space theory, respectively) does not hold in the setting abovePh.D.Includes bibliographical referencesby Ming Xia
The advantages and limitations of global datasets to assess carbon stocks as proxy for land degradation in an Ethiopian case study
No full textLand degradation leads to ecosystem degradation, reducing ecosystem functioning and depleting ecosystems' resilience. The majority of factors linked to land degradation are closely related with the depletion of below- and above-ground stocks of organic carbon. Organic carbon stock is important for climate change mitigation and for restoring soil functions such as those crucial to support food security. In this study, we mapped carbon stocks to infer land degradation in a small area in the Ethiopian Great Rift Valley. The study aimed to assess carbon stock status and to identify limitations and advantages of using global data in mapping at local scale relative to using local data. Two different datasets were developed; i) a “global dataset” characterised by data from datasets with global coverage data, and ii) a “hybrid dataset” that coupled data from global datasets, soil data derived from a local survey, and land cover data derived from a supervised classification of satellite images. The results showed that i) global datasets introduced inaccuracy that must be taken into account for advocating interventions at a local scale, and ii) global datasets could be used at a small catchment level for decision-making, if a simple rank of values is sufficient, but they might provide an optimistic picture of land degradation because they overestimate stocks
LoRaWAN Class B Multicast Scalability
No full textLoRaWAN has emerged as a popular IoT commu- nications technology. It comes with three classes of operation: A, B, and C. Although many IoT use-cases, like Firmware-over- the-Air updates, require multicast, Class A cannot be used for that purpose. Class C can, but consumes a lot of energy. This leaves Class B. In this paper, we investigate Class B multicast and its scalability properties. Issues like multicast member capacity, beacon blocking, and beacon collisions are highlighted, and several approaches to mitigate them are proposed: (1) “Ping-Slot Relaying,” to allow for more multicast members, (2) a scheduling approach indicating when to best send multicast packets, and (3) “Dynamic Region Formation” to coordinate the sending of beacons over multiple gateways. The proposed solutions do not require any modifications to the LoRaWAN protocol.Virtual/online event due to COVID-19 accepted author manuscriptEmbedded System
Adoption and diffusion of no tillage practices in Southern Spain olive groves
No full textThis paper analyses the process of adoption of no tillage in South-eastern Spain’s olive groves. Olive tree groves in South-eastern Spain’s mountainous areas are subject to a high risk of soil erosion, which is the main environmental problem for this crop, and have to incur in high costs of soil conservation. This results in a greater difficulty to comply with the practices required to benefit from both the single payment and agri-environmental schemes. In many high-steeped areas, farmers have opted for non-tillage practices as an alternative to other conservation practices. Using our own data from a survey carried out in 2006 among 215 olive tree farmers from the Granada Province in Southern Spain regarding the adoption of soil conservation and management practices, we model the diffusion process of no tillage practices using several specifications (logistic, Gompertz and exponential). We also estimate an ordered probit model to analyse which socio-economic and institutional factors determine the adoption of no tillage. Our results show that 90% of farmers in the area of study perform no tillage with either localized (21%) or no localized (69%) application of weedicides. The diffusion process of no tillage has been very intense since the middle nineties, and has been based on the interactions among farmers in the area of study rather than in external factors such as EU policies or extension services. Among other relevant factors that positively affect the adoption of no tillage practices in general, such as farm size and irrigation, the probability of a farmer adopting no tillage with non-localized application of weedicides increases when there is a relative that will continue with the farming activity, what causes the farmer to incorporate long term effects in his farming decisions, when the farmer is only a manager or when he bought the farm rather than inherited it (i.e. on more professionalized farms), and with his educational level. These results confirm some findings from previous studies in other nearby areas.Spanish olive groves, soil erosion, no tillage, Crop Production/Industries, Land Economics/Use,
Bacterial isolates and their antimicrobial susceptibility pattern among patients with external ocular infections at Borumeda hospital, Northeast Ethiopia
No full textBackground: Bacteria are major cause of ocular infections and possible loss of vision. The emergence of antimicrobial resistant bacteria increases the risk of treatment failure with potentially serious consequences. The aim of this study was to determine the prevalence of bacterial isolates and their antimicrobial susceptibility pattern among patients with external ocular infections. Methods: A cross sectional study was conducted among 160 patients with external ocular infections at Borumeda hospital, Northeast Ethiopia. Socio-demographic and clinical data were collected using structured questionnaire. External ocular specimens were collected using sterile swabs and inoculated on MacConkey agar, Chocolate agar and Blood agar culture Medias. Presumptive isolates were further identified by a series of biochemical tests. The antimicrobial susceptibility patterns of the isolates were determined by disk diffusion method. Result: The overall prevalence of bacterial pathogens among external ocular samples was 59.4 %. The majority of the isolates (93.7 %; 89/95) were Gram positive and the other 6.3 % (6/95) Gram negative bacteria. The proportion of coagulase negative Staphylococci among the Gram positive bacterial isolates was 53.7 % (n = 51/95). All Gram positive isolates were susceptible for vancomycin but 67.4 % (n = 60/95) of them were resistant against amoxicillin. Moreover, drug resistance to tetracycline, norfloxacylin, ceftriaxone and ciprofloxacin were observed among Gram negative bacteria isolates. Conclusion: The prevalence of bacterial pathogens among external ocular samples was high and the predominant isolate was coagulase negative Staphylococci. Exceptionally high amoxicillin resistance was observed among Gram positive bacterial isolates that may dictate to conduct drug susceptibility test routinely.Birtukan Shiferaw, Baye GelawEmail author, Abate Assefa, Yared Assefa and Zelalem Addi
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