Land uses and soil and water conservation (SWC) structures affect topsoil moisture and carbon stocks, particularly in the water deficit semi-arid environment of the northern Ethiopian highlands. This study was undertaken to assess the effects of land use and SWC structures on topsoil moisture, biomass, and soil carbon. Soil moisture was measured manually using gravimetric methods and theta probes with data loggers. Vegetation was inventoried and soil samples collected to assess carbon stocks of biomass and soils of different land uses. Merebmiti catchment had higher average gravimetric soil moisture content (GSMC; 24%) in wetlands, with the lowest (13%) in exclosures, whereas Mayleba catchment had relatively higher GSMC (14%) in exclosures and the lowest (8%) in rangelands. In both catchments, GSMC was higher at sampling locations closer to SWC structures than farther away. Merebmiti had significantly more biomass carbon (28.9 Mg ha−1) than Mayleba (6.32 Mg C ha−1). Higher soil organic carbon stocks were found in exclosures (46.1 ± 2.20 Mg ha−1) and wetlands (62.1 ± 2.9 Mg ha−1) than in frequently cultivated croplands (24.3 ± 1.4 Mg ha−1). Effective management of land use and implementation of SWC structures remarkably improves topsoil moisture content and carbon stocks in these catchments.

The excessive use of antibiotics in the pig breeding industry leads to the accumulation of antibiotic residuals in the environment, which is attributed to the improper treatment of livestock excrements. Sulfamethoxazole (SMX) and Norfloxacin (NOR) are antibiotics used in pig breeding and veterinary medicines as growth promoters and antibacterial drugs. The aim of this study was to examine the effects of these antibiotics and thermophilic pre-treatment on methane (CH₄) yield by anaerobic co-digestion (AcoD) of pig manure and corn straw under mesophilic temperature condition (35 ± 1 °C). We used antibiotics at a concentration of 0, 20 and 60 mg L⁻¹ (three stages) in two lab-scale continuously stirred tank reactors. The first reactor was run using untreated fed and the second reactor was run with thermophilic (55 ± 1 °C) pre-treated fed. The results showed that the CH₄ productions from reactor one were 205, 163 and 128 and from reactor two were 222, 185 and 173 mL CH₄ g⁻¹ VS_added, respectively. This elucidates that the presence of antibiotics had a negative effect on CH₄ production. Moreover, thermophilic pre-treatment improved the performance of the anaerobic digestion and CH₄ production.