Purpose A field study was conducted at Dire Dawa, Eastern Ethiopia, with an objective to find out an optimum combination of inorganic (NP) fertilizer and excreta-based vermicompost for best economic yield and quality of tomato and to assess their effect on selected physicochemical properties of amended soil after crop harvest. Methods The experiment consisted of eight treatments where the mineral (NP) fertilizer and the excreta-based vermicompost were combined in different proportions being arranged in a completely randomized block design replicated three times.Results Growth, yield and quality attributes of tomato as well as the post-harvest soil nutrient status were markedly influenced by the nutrient treatments. The highest values for the various growth, yield and quality attributing parameters were recorded for the treatment combination consisting 75% of the recommended rate of NP fertilizer ? 11.25 ton ha -1 vermicompost (T6), this treatment was also observed to have the highest net benefit with acceptable economic return as well as a fairly high residual soil nutrient status. Following this treatment, is the integration of 50% of recommended rate of NP fertilizer ? 7.5 ton ha -1 vermicompost (T3) which surpassed the sole mineral fertilizer and vermicompost in terms of the crop's yield and its economic return. Conclusion 25-50% of the recommended rate of chemical fertilizer can be supplemented through vermicompost. However, in order to generate more reliable information, there is a need to conduct more such studies using more integration ratios of these nutrient sources (NP fertilizer and vermicompost) at various soil and agro-climatic conditions.

Background:Composting is one of the integrated waste management strategies used for the recycling of organic wastes into a useful product. Composting methods vary in duration of decomposition and potency of stability, maturity and sanitation. This study was aimed to investigate the comparative effectiveness of four different methods of composting viz. windrow composting (WC), Vermicomposting (VC), pit composting (PC) and combined windrow and vermicomposting (WVC) on the stabilization, maturation and sanitization of mixtures of municipal solid organic waste and dried faecal sludge. Methods:The composting treatments were arranged in a completely randomized block design with three replications. The changes in physico-chemical and biological characteristics of the compost were examined at 20 days interval for 100 days using standard laboratory procedures. The analysis of variance was performed using SAS software and the significant differences were determined using Fisher's LSD test at P ≤ 0.05 level.Results: The evolution of composting temperature, pH, EC, NHratio, OC, C:N ratio and total volatile solids varied significantly among the composting methods and with composting time. The evolution of total nitrogen and germination index also varied significantly (P ≤ 0.001) with time, but their variation among the composting methods was not significant (P > 0.05). Except for PC, all other methods of composting satisfied all the indices for stability/maturity of compost at the 60th day of sampling; whereas PC achieved the critical limit values for most of the indices at the 80th day. A highly significant differences (P ≤ 0.001) were noted among the composting methods with regard to their effectiveness in eliminating pathogens (faecal coliforms and helminth eggs). The WVC method was most efficient in eliminating the pathogens complying with WHO's standard. Conclusion:Turned windrow composting and composting involving earthworms hastened the biodegradation process of organic wastes and result in the production of stable compost earlier than the traditional pit method of composting. The WVC method is most efficient in keeping the pathogens below the threshold level. Thus, elimination of pathogens from composts being a critical consideration, this study would recommend this method for composting organic wastes involving human excreta.© The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Efficient use of plant genetic diversity is a prerequisite for the development of crop varieties in meeting the challenges of food security and poverty alleviation. Understanding the variation and diversity of the genetic resources of crop species is there utilization and genetic resource conservation. This study was therefore conducted to estimate the genetic diversity of 114 Sweet potato [Ipomoea batatas (L.) Lam] accessions obtained from Nigeria, Asia, Latin America and Local collections along with two improved varieties. Accessions were planted in 2012/13 cropping season at Haramaya University, eastern Ethiopia using Augmented design and evaluated for 17 agro traits. Significant differences among accessions were observed for all traits except four. Varying number of accessions obtained from Asia, Nigerian and Ethiopia performed better than improved varieties for all the traits. Heritability in broad sense and genetic advance ranged from 3.68 to 97.64 and 1.27 to 42.21%, respectively. The estimated genetic distance of 6670 pairs of accessions using Euclidean distance varied from 2.04 to 11. The Nigeria and Ethiopia collections were most distant as compared to other pairs of accessions. The dendrograms from Unweighted Pair-group Method with Arithmetic means (UPGMA) resulted in the formation of 12 clusters, which consisted accessions from different sources except Cluster III and XI, which contained accessions only from Asia. The research revealed t improving the crop through selection and the importance of further maintaining of these accessions for future improvement regardless of their geographical origin. Moreover, varied number of local collections performed better than higher p for all the traits and it was evident the presence of wide variation and genetic diversity among local and between other countries accessions. This suggested the importance of further collection, evaluation and maintaining of Sweet potato cultivars used by farmers in different regions of the country, which were introduced at different time.

Limited tolerance of common beans (Phaseolus vulgaris L.) to cold temperatures hinders an additional harvest during the small rainy season crop cycle (February to May) in the Ethiopian highlands that comprise two-thirds of the country. Therefore, identification of cold tolerant common bean genotypes is of paramount importance for the region. Field screening of 99 common bean genotypes originally procured from CIAT (International Center for Tropical Agriculture) was carried out for nine different plant traits associated with crop growth and yield at two locations differing in climates: Dire Dawa-higher daily maximum and minimum temperatures and absence of near zero chilling temperatures from February to May; Haramaya-lower daily maximum and minimum temperatures and occasionally near zero chilling temperatures during this period. The analysis of variance (ANOVA) showed the existence of significant variation among genotypes for the parameters measured. Principal component analysis (PCA) was carried out to assess the variation and correlation among genotypes for the traits and group them based on their performance at the two locations. The combination of first three principal components explained more than 50% of the genotypic variations. Principal component analysis was also able to discriminate the performance of genotypes between the two locations. It was grouped into at least 17 genotypes that were specific to Haramaya highland location. The results also revealed significant variation in performance among the 17 genotypes. These genotypes are specific to Ethiopian highlands and prominent resources for in-situ conservation of germplasms.