Coffee forests are the most valuable land-use systems that provide multiple benefits such as biodiversity conservation, carbon sequestration and source of income. This study aimed to estimate the carbon stock of coffee agroforestry systems and the contribution of coffee plants (Coffea arabicaL.) to carbon sequestration in the entire coffee agroforestry systems in southwestern Ethiopia. The carbon stock in trees was estimated by field-based measurements and allometric equations, whereas the carbon stocks in litter and soil were determined using field sampling and laboratory analysis. The carbon stocks of the coffee agroforestry systems in the study site ranged from 254.9 t C/ha in the Syzygium-shaded coffee forest to 321.8 t C/ha in the Albizia-shaded coffee forest. The overall mean carbon sequestration in the present coffee agroforestry systems was 287.1 t C/ha. The net carbon sequestered by coffee plants in the agroforestry systems ranged from 18.8 t C/ha in the Syzygium-shaded coffee stratum to 48.5 t C/ha in the Albizia-shaded coffee stratum. This demonstrates that Albizia is the most compatible shade tree for coffee plants. On average, coffee plants contributed 37.5 t C/ha, accounting for approximately 12.8% of the total carbon sequestered in the coffee agroforestry systems. Hence, we recommend coffee forests for all-in-one benefits such as climate change mitigation, sustainable landscape management and income generation.

Indigenous weather forecasting systems of Borana pastoralists are among the core elements of a Gada system that existed half a million years back and still serving as a powerful natural intelligence on adaptation to climatic hazards. The study was aimed to investigate the types of indigenous weather forecasting systems, mechanisms of climate information exchange, and how traditional forecasts have been integrated with contemporary forecasts to strengthen adaptation to climatic hazards in Borana pastoralists of southern Ethiopia. Conventional survey methods including participatory rural appraisal tools and factorial scoring technique were used for data collection and interpretation. This study indicated that four major indigenous weather forecasting systems were used by Borana pastoralists for centuries. These include Ayantu, Uchu, Waragu, and Arga-Dhageti. They varied in the kind of indicator used to predict weather events. Forecasting was mainly based on observation and unique analysis of celestial bodies, atmospheric variables, and biological features. Respondents indicated that Uchu and Ayantu systems were the most trusted and reliable sources of local climate information. Indigenous and contemporary forecasts are just different and could complement each other. Our results indicated that integrating indigenous and forecasting contemporary systems can foster the prediction efficiency and applicability of climate information. Borana pastoralists had established coping mechanisms that were performed in three phases: pre, during and post occurrence of predicted weather events; mainly aimed at improving their resilience to climatic shocks. Therefore, sustaining such sacred indigenous knowledge bank is vital, as it directly supports community-based disaster risk reduction programmes.

Ameliorating soil acidity using a combination of lime and organic amendments (OAs) can be an alternative to lime alone, but determining the appropriate OA rates can be difficult. We developed a new method for calculating the combined application rate of lime and OAs (wheat straw, faba bean straw, blended poultry litter, biochar, and compost) that is based on the titratable alkalinity of OAs and the equilibrium lime buffer capacity (LBC_eq) of acidic soils. The effect of calculated soil amendment rates on soil pH was validated at soil water contents of 60 %, 100 %, and 150 % of field capacity (FC). The soil used to develop and validate the method was a sandy loam with a soil pH in deionised water (pH_W) of 4.84 and a soil pH in 0.01 M CaCl₂ solution (pH_Ca) of 4.21. The LBC_eq of the soil was 1657 mg CaCO₃ kg⁻¹ pH⁻¹ (where “CaCO₃ kg⁻¹ pH⁻¹” denotes the amount of lime required to raise the pH of 1 kg of soil by one unit). The titratable alkalinity of the OAs ranged from 11.7 cmol H${}_{\mathrm{eq}}^{+}$ kg⁻¹ for wheat straw to 357 cmol H${}_{\mathrm{eq}}^{+}$ kg⁻¹ for compost. At 60 % FC, faba bean and wheat straw amendment increased the soil pH_W to 6.48 and 6.42, respectively, but lower pH values were reached in soil amended with less biodegradable or resistant OAs (ROAs) (i.e. blended poultry litter, biochar, and compost). At 150 % FC, the two straws increased the soil pH_W to only 5.93 and 5.75, respectively, possibly due to slower decomposition under submerged conditions, resulting in limited alkalinity production, whereas amendment with ROAs produced pH_W values close to 6.5. With an increasing lime-equivalent value (LEV) of the OA, from 5.8 g CaCO₃ kg⁻¹ (wheat straw) to 179 g CaCO₃ kg⁻¹ (compost), the lime requirement to reach pH_W 6.5 in lime–OA combinations decreased from 2.72 to 0.09 g CaCO₃ kg⁻¹. The developed method was shown to be effective in determining the appropriate rates of OAs (with or without additional lime) for the management of acidic sandy loam soils in this study and highlights the importance of the soil water content with respect to its acid-neutralising effect.

Background: Understanding the spatial variability of soil properties is useful to tailor site-specific agricultural inputs to enhance crop production on a sustainable basis. This study was aimed to assess and map the spatial patterns of soil acidity and nutrients using geostatistical methods and support site-specific lime and fertilizer recommendations in Bedele district, Southwestern Ethiopia.Methods: Soil samples were collected from agricultural land at a depth of 20 cm using grid sampling technique. The semivariogram analysis was performed for accurate spatial prediction and the kriging technique was used for interpolation of soil parameters.Results: Soil pH varied between 4.5 and 6.8. Soil organic carbon (OC) content ranged from 0.3 to 5.6% and the mean soil OC density was 0.81 kg m⁻². Available phosphorus (AvP) ranged from 0.8 to 38.6 mg kg⁻¹and nearly 80.23% of the soils exhibited very low to low AvP that could be due to fixation by strong acidity. Soils of the study area exhibited very high exchangeable potassium (K), but very low exchangeable calcium (Ca) and magnesium (Mg). The potassium to magnesium ratio (K:Mg) ranged from 0.2:1 to 10.9:1, while the values of calcium to magnesium ratio (Ca:Mg) varied between 0.3 and 3.4. Among the soil parameters, exchangeable Ca (CV = 54%) and K:Mg ratio (CV = 57.62%) were more variable than other soil parameters. Spatial variability was lowest for soil pH (CV = 10%).Conclusions: Major portions of the study site were affected by strong acidity (pH ≤ 5.5). Accordingly, about 89% of the soils require lime that varied between 0.09 and 3.6 tons ha⁻¹. In addition to soil acidity, deficiency of available P, Ca, and Mg were the major liming factors affecting crop production in the study area. Digital soil mapping was used to show the spatial variability of soil acidity and nutrients across agricultural land and applied for efficient lime and nutrients advisory works.

The study examined the impact of deforestation and subsequent cultivation on soil fertility and acidity conditions under varying soil depths. Soil profiles were opened in two adjacent land units, namely forestland and arable land and samples were collected from genetic horizons. Deterioration of soil fertility was observed after deforestation and traditional cultivation. The main aim of deforestation was agricultural expansion. Soil pH consistently decreased with depth in both land units and it was relatively lowest in arable land perhaps due to depletion of organic matter (OM) and decrease in buffering capacity of the soil. The OM and total nitrogen (N) ranged from 0.78 and 0.06% in the 75 to160 cm layer of arable land to 15 and 0.61% in the 0 to10 cm layer of forestland, respectively. Total N was strongly and positively correlated with soil OM (r = 0.99). Exchangeable Al was poorly and negatively correlated with available phosphorous (r = -0.41). Conversion of forestland to arable land reduced the mean available phosphorus (P) from 4.04 ppm to 1.95 ppm most probably due to decline in OM, soil acidification and erosion. Deforestation and subsequent continuous cultivation over the past 25 years apparently amplified the mean exchangeable acids from 0.83 cmol (+) kg-1 to 5.96 cmol (+) kg-1. Soil acidification and related problems were the major challenges of continuous cultivation in the study area. The study indicated that land use change and management practices have had a considerable negative effect on soil physical and chemical properties. Key words: Deforestation, continuous cultivation, land use change, soil properties, soil fertility, soil acidity, Western Ethiopia.