This study aims to investigate soil organic carbon (SOC) and total nitrogen (TN) contents and stocks, CO₂emissions and selected soil properties in croplands, grazing lands, exclosures and forest lands of semi-arid Ethiopia. Sampling was done at 0–30, 30–60 and 60–90 cm soil depths and concentration and stocks of SOC, TN and selected soil properties were determined using standard routine laboratory procedures. There were variations in distribution of SOC and TN stock over 90 cm depth across land use types and locations, decreasing from topsoils to subsoil, with average values ranging from 48.68 Mg C ha⁻¹and 4.80 Mg N ha⁻¹in Hugumburda cropland to 303.53 Mg C ha⁻¹and 24.99 Mg N ha⁻¹in Desa’a forest respectively. Forest sequestered significant higher SOC and TN stock, decreasing with depth, compared with other land use types. In Desa'a and Hugumburda, the conversion of forest to cropland resulted in a total loss of SOC stock of 9.04 Mg C ha⁻¹and 2.05 Mg C ha⁻¹, respectively, and an increase in CO₂emission of 33.16 Mg C ha⁻¹and 7.52 Mg C ha⁻¹ yr⁻¹, respectively. The establishment of 10 years (Geregera) and 6 years (Haikihelet) exclosures on degraded grazing land increased SOC stock by 13% and 37% respectively.

The consequences of prolonged precipitation-deficient periods are primarily substantial water deficit. The spatial characteristics of drylands and various socioeconomic factors worsen droughts’ impacts and deepen poverty among agrarian communities, with attendant food security (stability dimension) implications. This study utilizes a combination of climate, remote sensing and field survey data to obtain first-hand information on the impacts of recent (2015 and 2017) droughts on crop yield in southern Tigray, northern Ethiopia. Annual and seasonal rainfall, annual and seasonal Normalized Difference Vegetation Index (NDVI) and Deviation of NDVI (Dev-NDVI), and monthly Standardized Precipitation Index (SPI) (SPI-1, SPI-3 and SPI-12) for June to October, were considered as likely factors that could relate with yield and yield loss in the area. Correlation and multiple linear stepwise regression statistical techniques were used to determine drought-yield relationships, and identify more accurate predictors of yield and yield losses in each of the drought years. The area witnessed a more widespread precipitation deficit in 2015 than in 2017, where the lowland area recorded entire crop (sorghum) losses. Also, droughts manifested spatiotemporal variations and impacts across the two different agroecologies—primarily reduction in vegetation amounts, coinciding with the planting and maturing stages of barley and sorghum. Crop failures, therefore, translated to food shortages and reduced income of smallholder farmers, which denotes food insecurity in the time of droughts. Seasonal rainfall and June Dev-NDVI predicted 66.9% of 2015 barley and sorghum yield-loss, while NDVI predicted 2017 sorghum yield by 96%. Spate irrigation should be further popularized in the low-lying areas of Raya Azebo to augment for future deficiencies in the kiremt rainfall.

Enyigba in south-eastern Nigeria is one of the agrarian communities facing water scarcity challenges. The open cast mining activities in the region are also compounding the water problems as a result of leakage of heavy metals that pollute the limited water resources. This study is conducted to document the current state of surface water contamination by heavy metals and its impact on domestic and agricultural uses. Thirty water samples were collected from five sources at both the upstream, middle stream and downstream of each of the selected sites. The heavy metals were analysed using the standard laboratory methods. Generally, the average concentrations of As, Cd, Cu, Pb and Zn in the studied water bodies were 17.68, 4.30, 3.14, 0.05 and 35.57 mg/l, respectively, which were above the WHO permissible limit. Contamination of water above WHO permissible limits with heavy metals in the surface waters, because of open cast mining, is considered a serious threat to both domestic and agricultural usage. The need for establishment of treatment facility, periodic monitoring of heavy metal levels, recycling plants and principal technologies to monitor the mine sites are hereby recommended.

In the face of climate change and global warming, scientists globally are striving for effective techniques on how best to sequester carbon in order to reduce global warming and achieve environmental sustainability. This paper reviews the available literature on the influence of various land use changes on gains and/or losses of soil carbon (C) stocks in Ethiopia. Our review indicated that 33.3% of the studies reported soil organic carbon (SOC) concentration, 13.9% reported only SOC stock while 52.8% reported both SOC concentration and stock. Studies focusing on 0–30 cm only were 44%, other studies extending up to 40 to 100 cm were 50%, and studies extending to more than 100 cm accounted for 2.8% while studies without any depth specification accounted for 2.8%. Irrespective of soil type, C stocks in the top soil (0–30 cm) were found to be higher than at subsoil depths. Even though there is significant improvement in C sequestration in exclosures and community forests, the level of C sequestered is still below that of church forests. Conversion of native forest to other land uses resulted in a significant decrease in the SOC stocks across Ethiopia. Absence of long-term field trials and non-existence of SOC database are among the major drawbacks of SOC studies in Ethiopia identified in this review. With better management practices, it is possible to restore depleted C concentrations and stocks even in degraded lands and to conserve C in more pristine lands across the rugged landscapes of Ethiopia.

The purpose of this study was to explore how soil fertility management and farm nutrient balances varied across socio-economic groups in northern Ethiopia. Field surveys were carried out in 32 farms in Tigray, northern Ethiopia using different socio-economic groups, viz.: model/non model and female/male farmers. The nutrient input flows and output flows were monitored and analysed using Monitoring for Quality Improvement (MonQI) toolbox. Results of the study showed that average nitrogen (N), phosphorus (P) and potassium (K) balances in the highlands were − 30.8, 4.08 and − 42.75 kg ha⁻¹, respectively while in the lowland the average nutrient balance were − 19.5, 2.09 and − 15.35 kg ha⁻¹ for N, P and K, respectively. All farms had negative N and K nutrient balances, with lower negative N and K balance recorded in highlands than the lowlands. The reported values account about 0.6% and 2.7% of the total soil N and K pools in the highland and 0.3% and 0.8% in the lowland, respectively. Nutrient depletion rates in the highlands were 0.6% year⁻¹ and 2.7% year⁻¹ for N and K, respectively while for the lowlands the rates were 1.5% year⁻¹ and 3.4% year⁻¹ for N and K, respectively. Depletion rates were higher in the lowlands than highlands due to monocropping, crop residue removal and absence of soil water conservation. Most farms belonging to model farmers of both categories and non-model male farmers show more negative nutrient balance. We conclude that socio-economic status and being model farmers had less role in soil fertility maintenance. However, the more positive balance in female-headed households points to the need for adequate attention and support for the female-headed households. This study underscores the need for sustainable nutrient management. More so, agricultural policy should target female-headed households to help reduce the productivity gap between male-headed households and female-headed households.