A B S T R A C TIn response to the intensive tillage in maize, operating under high seasonal rainfall variability, this study examined the agronomic and economic responses of tillage and water conservation management in the central rift valley (CRV) of Ethiopia. An experiment was laid out as a split plot design with conventional tillage (CT), minimum tillage (MT) and zero tillage (ZT) as main plots and mulch, no mulch and planting basin as subplots. The MT and ZT were considered as conservation agriculture (CA) plots. Results showed that CT had 13-20% higher grain yield than MT and 40-55% higher than ZT; and MT had 27-37% higher yields than ZT. Mulching had 23-33% and 14-19% higher grain yield than no mulch and planting basin respectively. The CT had 28 and 89% higher labor productivity and 6 and 60% higher gross margin than MT and ZT respectively. The MT had 37% higher gross margin than ZT. The highest yield response in CT resulted in its highest gross margin and labor productivity. This shows that regardless of water conservation management, CT yielded better agronomic and economic responses over CA. However, the practice of CT is highly constrained by the availability of draft power and the short window period for planting. Likewise, regardless of tillage management, mulching tended to be more attractive and promising in suppressing weed density and hence reducing labor demand for weeding, despite improving volumetric soil moisture content and maize yield. Yet the viability of practicing mulching is highly constrained by the widely practiced open grazing on stubble after harvest. Therefore, future studies are needed to further identify appropriate tillage and water conservation management which make maize more resilient to the high rainfall variability, and sustainably improve food security, and farmers' livelihoods in the CRV of Ethiopia.2014 Published by Elsevier B.V.

This study examines the agronomic response, efficiency and profitability of fertilizer microdosing in maize. An experiment with the following treatments was conducted: control without fertilizer, microdosing treatments, with the rate of 27 + 27, 53 + 53 and 80 + 80 kg ha fertilizer rate increased the grain yield by 19, 45 and 46% at Hawassa, Ziway and Melkassa, respectively, and it was equivalent to the higher rates. The value cost ratio (VCR) was highest with the lowest fertilizer rate, varying between seven and 11 in the treatment with 27 + 27 kg ha of DAP + urea rate makes it low cost, low risk, high yielding and profitable. Therefore, application of this particular rate in maize may be an option for the marginal farmers in the region with similar socioeconomic and agroecological conditions. OPEN ACCESSAgronomy 2014, 4 437

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Background: Renewable energies such as biogas are considered as clean sources of energy that minimize environmental impacts and are sustainable with regard to current and future economic and social needs. Biogas offers an attractive option for replacing the unsustainable usage of traditional energy sources such as firewood, cow dung, and charcoal in developing countries. In Ethiopia, these energy sources have been in decline. To address these challenges, mainly in rural areas, biogas technology has been domesticated since 2009, as seen in the National Program. The purpose of this study is thus to examine factors that influence households' decisions of adopting biogas technology in rural areas in southern Ethiopia. Methods: A sample of 268 households with 134 biogas adopters and 134 non-adopters were surveyed using simple random and purposive sampling techniques, respectively. The data were collected through individual interviews of households using a semistructured questionnaire. Descriptive statistics and a binary logistic regression model were used for the data analysis. The binary logistic regression model was applied to identify determinant factors affecting the adoption of biogas technology. Results: The results of the study indicated that biogas adopter and non-adopter households had significant mean differences in education level, cattle size, household income, farmland size, number of planted trees as well as the distance to water sources, market places, and firewood sources. Level of education, level of income, access to credit, distance to firewood sources, and access to electronic media had a significantly positive influence on the adoption of biogas technology. Conversely, distance to water sources and access to electricity had a significantly negative influence on the adoption of biogas technology. Conclusions: Biogas technology mostly appears in privileged households having a better socioeconomic status and other resource endowments. The beneficiaries are thus households that can afford the higher initial investment costs for bio-digester installation, maintenance services and purchasing bio-digester spare parts; as well as households that have access to credit facilities, water sources for adequate water supply, markets for purchasing spare parts and electronic media for information, and also households residing far away from firewood sources.