Biochar addition reduces non-CO2 greenhouse gas emissions during composting of human excreta and cattle manure.

Ecological sanitation combined with thermophilic composting is a viable option to transform human excreta into a stabilized, pathogen-free, and nutrient-rich fertilizer. In combination with suitable bulking materials such as sawdust and straw, and additives such as biochar, this could also be a suitable waste management strategy for reducing greenhouse gas (GHG) emissions. In this study, we conducted a 143-days thermophilic composting of human excreta or cattle manure together with teff straw, organic waste, and biochar to investigate the effect that biochar has on GHG (CO2 , N2 O, and CH4 ) and NH3 emissions. The composting was performed in wooden boxes (1.5 × 1.5 × 1.4 m3 ), GHG were measured by using a portable FTIR gas analyzer and NH3 was sampled as ammonium in an H2 SO4 trap. We found that the addition of biochar significantly reduced CH4 emissions by 91% in the cattle manure compost, and N2 O emissions by 56%-57% in both humanure and cattle manure composts. Overall, non-CO2 GHG emissions were reduced by 51%-71%. In contrast, we did not observe a significant biochar effect on CO2 and NH3 emissions. Previous data already showed that it is possible to sanitize human fecal material when using this composting method. Our results suggest that thermophilic composting with biochar addition is a safe and cost-effective waste management practice for producing a nutrient-rich fertilizer from human excreta, while reducing GHG emissions at the same time.

Assessment of implemented physical designs and determinant factors of soil and water conservation measures: Wenago district, southern Ethiopia.

Soil erosion and its consequences is one of the major serious problems in Ethiopia. Even though adoption of soil and water conservation (SWC) measures has been underway for the past three decades, the implementation and use of introduced technologies were below the expectation and the problem is still has continued in the country. The study was aimed at assessing the implemented physical designs of soil and water conservation structures in respect to the standards and identifying the major adoption determinant factors in Wenago district, southern Ethiopia. The data for this studywas collected from a survey of 262 total household farmers selected through simple random sampling techniques in the year 2020/21 and the datawas analyzed using descriptive statistics, chi-square and logistic regression model via SPSS and Stata soft wares. Focus group discussion, key informant interview and personal observation were also undertaken to gather data having qualitative nature. (i) About 55.6% of the implemented physical design failed to meet the standards (ii) Adoption of SWC measures were determined by 47.4% of the tested variables (iii) 55.5% of the variables were significantly associated at 5% probability level between adopters and non-adopters in terms of adoption of SWC measures in the study area. Overall, we conclude that construction of conservation structures should be focused on minimizing the observed mismatch of the implemented physical designs against the standards. This study is expected to contribute in achieving sustainable land management schemes, agricultural productivity and smallholder farmers livelihood improvement in international, national, regional and local level and it is strongly recommended that policy makers and technical institutions should address SWC related issues to ensure rural farmers food security.

Nutrient dynamics during composting of human excreta, cattle manure, and organic waste affected by biochar.

Ecological sanitation via thermophilic composting could be a promising solution to the lack of sanitation and limited access to fertilizers, particularly in developing countries. Here, we conducted a 185-d thermophilic composting experiment with human excreta, and separately with cattle manure, mixed with kitchen scraps, teff [Eragrostis tef (Zuccagni) Trotter] straw, sawdust, and biochar (BC) by using an appropriate-technology approach. We followed the dynamics of the most important macronutrients (N, P, K), temperature, moisture, pH, electrical conductivity, cation exchange capacity, as well as content of organic matter, organic C, Ca, Mg, and micronutrients throughout the process. Low N (<47%), P (<9%), K (<11%), Ca (<18%), and Mg (<21%) losses and the temperature profile indicated a well-functioning thermophilic composting process. Compost temperature was >60 °C for 7, 6, 5, and 8 consecutive days for treatments containing human excreta, human excreta amended with BC, cattle manure, and cattle manure amended with BC, respectively, suggesting a final compost product free of pathogens. The compost mixture with cattle manure and BC reached a significantly higher temperature than the same variant without BC, with a maximum value of 65.9 °C on Day 6. For all treatments, final germination index values >100% indicated compost maturity and the absence of phytotoxic substances. Biochar addition reduced losses of organic matter (18-23%), C (33-42%), and N (49-100%) and decreased the amount of extractable NO3 - (32-36%) in the final compost. The tested ecological sanitation concept via thermophilic composting is thus a promising strategy to improve access to cheap fertilizer by safe and sustainable sanitation and waste management.

Building future scenarios and uncovering persisting challenges of participatory forest management in Chilimo Forest, Central Ethiopia.

We examined the changes in forest status and people's livelihoods through building future scenarios for Chilimo Forest in Central Ethiopia where participatory forest management (PFM) is being implemented. Participatory methods were employed to collect data, and a dynamic modeling technique was applied to explore trends over time. By integrating the more quantitative model outputs with qualitative insights, information on forests and livelihoods was summarized and returned to users, both to inform them and get feedback. A scenario of open access without PFM provides higher income benefits in the short term but not over the longer term, as compared to a scenario with PFM. Follow up meetings were organized with national decision makers to explore the possibility of new provisions in the national forest proclamation related to joint community-state ownership of forests. Project implementers must constantly work towards improving short term incentives from PFM, as these may be insufficient to garner support for PFM. Other necessary elements for PFM to succeed include: ensuring active participation of the communities in the process; and, clarifying and harmonizing the rules and regulations at different levels.