Proper management and effective conversion of biomass residues for biofuel production are crucial to reduce deforestation due to the cutting of trees for cooking and heating as a primary source of fuel and improving energy utilization of households. Thus, this study is aimed at investigating the effects of biomass residues of the coffee husk (CH), sawdust (SD), khat waste (KW), and dry grass (DG) and binding materials prepared from the waste paper pulp (PP) and clay soil (CS) under a low-pressure piston press densification machine. The biomass waste and binders were combined in a 3 : 1 ratio of CH : PP, CH : CS, SD : PP, SD : CS, KW : PP, KW : CS, DG : PP, and DG : CS. The briquettes were produced using a manually operated closed-end piston press machine compacted at an average pressure of 2 MPa. Briquette proximate and ultimate analysis of moisture content, volatile matter, fixed carbon, and ash content was determined using standard ASTM methods, while the calorific value was determined using a bomb calorimeter and data analysis was carried out using the R-program. Results revealed that the briquette produced from biomass residues has a mean value of fixed carbon and calorific value that ranged from 38.62 ± 1.53 to 41.75 ± 2.14 and 3979.21 ± 232.05  cal/g to 4577.34 ± 397.11  cal/g, respectively. Generally, briquettes produced from saw dust residue and the paper pulp binder had better quality of fuel and this could be used as an alternative source of energy and proper waste management option.

The high production potential of coffee and animals in the Gedeo zone that could produce huge amounts of coffee pulp and animal manure wastes has been polluting the environment. In this sense, this study was aimed at averting pollution and managing plant and animal wastes, focusing on the effect of coffee pulp and animal manure in the form of vermicompost, biochar, and ordinary compost on hot pepper vegetative and reproductive growth. A 15 ton per hectare of each treatment was applied in a randomized complete block design replicated three times. Vegetative and reproductive growth parameters (plant height, leaf number, number of branches, days to 50% flowering, total fresh biomass, number of fruits per plant, single fruit length, and fruit yield per hectare) were recorded, and the statistical difference was determined at 5% significance level using R-program. The result showed that there was a significant difference among treatments. Coffee pulp vermicompost prepared using Eisenia fetida earthworm had significantly ( P < 0.05 ) higher results in plant height, leaf number, number of branches, total fresh biomass, number of fruits per plant, single fruit length, and total yield, while the minimum values were recorded in topsoil (control treatment) and animal manure compost. The direct and residual effects of vermicompost and biochar organic amendments were the potential organic fertilizers for hot pepper fast growth and to produce enormous yield, which might be due to their nature in improving soil physicochemical and biological properties as well as nutrient uptake.

Urban forests have an important role in biodiversity conservation, environmental improvement, and ecosystem services including climate change mitigation enhancement. The objectives of the current study were to: assess plant types and management strategies of the owners; woody species’ composition, structure, and diversity; and estimate aboveground biomass of trees and associated carbon stock in private residential green infrastructure (PRGI) at Dilla town. This study was conducted at three kebeles, the lowest administrative unit in Ethiopia. Ninety-four households were randomly selected from a proportional sample size for each kebele. A complete inventory of woody species was done after measuring the area occupied by plants at each household. At plot level, the aboveground biomass of sampled trees was calculated by using an allometric biomass equation developed for agroforestry species. Diversity was described by using different indices The free software EstimateS 9.1.0 was used to generate data for the construction of sample-based rarefaction curves and SPSS version 20 for descriptive statistics. Based on plant types and arrangement, the households manage their PRGI in 15 categories on area size, ranging from 10 m2 to 1229 m2, with an average holding size of 207.5 m2. A total of 66 plant species belonging to 45 families were identified. Overall, a total of 1220 stem ha−1 contributed to an aboveground carbon stock of 64.35 ton ha−1 of which 50.4% is from fruit trees and the rest from timber trees. The results suggest that PRGIs can serve as reservoirs of non-native and native plant species, including five native tree species currently facing conservation concerns.