We have created this Blog and the database to provide a place where the scientific community can share and update the fast growing knowledge and data on the study of greenhouse gas CO2, CH4, and N2O fluxes in Africa.

We are grateful for the numerous researchers and technicians who provide invaluable data. It is impossible to cite all the references due to limited space allowed and we apologize for the authors whose work has not been cited.

Bateganya et al. 2015. Carbon and nitrogen gaseous fluxes from subsurface flow wetland buffer strips at mesocosm scale in East Africa.

Bateganya, N.L., Mentler, A., Langergraber, G., Busulwa, H. and Hein, T., 2015. Carbon and nitrogen gaseous fluxes from subsurface flow wetland buffer strips at mesocosm scale in East Africa. Ecological Engineering, 85: 173-184.


This study investigated carbon (CH4, CO2) and nitrogen (N2O) gaseous fluxes as finger prints for microbial wastewater treatment processes in vertical (VF) and horizontal (HF) subsurface flow mesocosms, planted with Cyperus papyrus and operated under batch hydraulic loading. The closed chamber method was used to measure gaseous emissions for 12 weeks (April–June 2014) in Kampala, Uganda. Organic matter (OM) (BOD5 and COD) and inorganic nitrogen (NH4+ and NO3) nutrient concentrations were monitored to estimate OM degradation rates and potential nitrification and denitrification. The highest mean CH4 flux (mg CH4single bondC m−2 h−1) was 38.3 ± 3.3 in unplanted HF compared to the lowest (3.3 ± 0.4) established in planted VF mesocosms. CO2 fluxes (mg CO2single bondC m−2 h−1) were significantly higher (P < 0.05) in planted mesocosms, with no significant difference (P > 0.05) between the planted HF (2213.5 ± 122.4) and VF (2272.8 ± 191.0) mesocosms. The high CO2 flux was attributed to efficient degradation of the inflow organic carbon facilitated by sufficient oxygen supply especially in the planted mesocosms. Although N2O flux was relatively higher in HF mesocosms, it did not vary significantly (P > 0.05) in all treatments. Generally the results indicated significant nitrification, especially in the planted mesocosms. However, high fluxes of N2O comparable to other denitrifying CWs suggested potential for coupled nitrification and denitrification in these systems. Overall, compared to CH4 and N2O, CO2 was found to be the most significant gaseous flux under induced aerobic conditions enhanced by use of C. papyrus plants and an intermittent loading regime.

Pelster et al. 2015. Smallholder African farms in western Kenya have limited greenhouse gas fluxes

Pelster, D.E., Rufino, M.C., Rosenstock, T., Mango, J., Saiz, G., Diaz-Pines, E., Baldi, G., Butterbach-Bahl, K., 2015. Smallholder African farms in western Kenya have limited greenhouse gas fluxes. Biogeosciences Discuss. 12, 15301-15336.

Few field studies examine greenhouse gas (GHG) emissions from African agricultural systems resulting in high uncertainty for national inventories. We provide here the most comprehensive study in Africa to date, examining annual CO2, CH4 and N2O emissions from 59 plots, across different vegetation types, field types and land classes in western Kenya. The study area consists of a lowland area (approximately 1200 m a.s.l.) rising approximately 600 m to a highland plateau. Cumulative annual fluxes ranged from 2.8 to 15.0 Mg CO2-C ha−1, −6.0 to 2.4 kg CH4-C ha−1 and −0.1 to 1.8 kg N2O-N ha−1. Management intensity of the plots did not result in differences in annual fluxes for the GHGs measured (P = 0.46, 0.67 and 0.14 for CO2, N2O and CH4 respectively). The similar emissions were likely related to low fertilizer input rates (≤ 20 kg ha−1). Grazing plots had the highest CO2 fluxes (P = 0.005); treed plots were a larger CH4 sink than grazing plots (P = 0.05); while N2O emissions were similar across vegetation types (P = 0.59). This case study is likely representative for low fertilizer input, smallholder systems across sub-Saharan Africa, providing critical data for estimating regional or continental GHG inventories. Low crop yields, likely due to low inputs, resulted in high (up to 67 g N2O-N kg−1 aboveground N uptake) yield-scaled emissions. Improving crop production through intensification of agricultural production (i.e. water and nutrient management) may be an important tool to mitigate the impact of African agriculture on climate change.

Borges et al. 2015. Globally significant greenhouse-gas emissions from African inland waters

Borges A V, Darchambeau F, Teodoru C R, Marwick T R, Tamooh F, Geeraert N, Omengo F O, Guerin F, Lambert T, Morana C, Okuku E and Bouillon S 2015 Globally significant greenhouse-gas emissions from African inland waters. Nature Geosci doi:10.1038/ngeo2486.


Carbon dioxide emissions to the atmosphere from inland waters—streams, rivers, lakes and reservoirs—are nearly equivalent to ocean and land sinks globally. Inland waters can be an important source of methane and nitrous oxide emissions as well, but emissions are poorly quantified, especially in Africa. Here we report dissolved carbon dioxide, methane and nitrous oxide concentrations from 12 rivers in sub-Saharan Africa, including seasonally resolved sampling at 39 sites, acquired between 2006 and 2014. Fluxes were calculated from published gas transfer velocities, and upscaled to the area of all sub-Saharan African rivers using available spatial data sets. Carbon dioxide-equivalent emissions from river channels alone were about 0.4 Pg carbon per year, equivalent to two-thirds of the overall net carbon land sink previously reported for Africa. Including emissions from wetlands of the Congo river increases the total carbon dioxide-equivalent greenhouse-gas emissions to about 0.9 Pg carbon per year, equivalent to about one quarter of the global ocean and terrestrial combined carbon sink. Riverine carbon dioxide and methane emissions increase with wetland extent and upland biomass. We therefore suggest that future changes in wetland and upland cover could strongly affect greenhouse-gas emissions from African inland waters.

Kimaro et al. 2015. Is conservation agriculture ‘climate-smart’for maize farmers in the highlands of Tanzania?

Kimaro, A. A., Mpanda, M., Rioux, J., Aynekulu, E., Shaba, S., Thiong’o, M., ... & Rosenstock, T. S. (2015). Is conservation agriculture ‘climate-smart’for maize farmers in the highlands of Tanzania?. Nutrient Cycling in Agroecosystems, 1-12.


Conservation agriculture (CA) is promoted extensively to increase the productivity and environmental sustainability of maize production systems across sub-Saharan Africa and is often listed as a climate-smart agriculture (CSA) practice. However, the impacts of CA on food security, resilience/adaptive capacity and climate change mitigation are location-dependent and it is unknown whether CA can simultaneously address CSA’s multiple objectives. Here we evaluate four variations of CA: reduced tillage plus mulch (mulch), reduced tillage plus mulch and leguminous cover crop (Lablab), reduced tillage plus mulch and leguminous trees (CAWT), and reduced tillage plus mulch and nitrogen fertilizer (CA + F)—for their effect on CSA-relevant outcomes in highland Tanzania maize production. By comparison to conventional practice in the region, intensification of maize production by Lablab, CAWT, and CA + F significantly increases yields by 40, 89 and 77 %, respectively. Likewise, rainfall use efficiency was highest in these three treatments and significantly greater than conventional practices in 7 of 12 comparisons. Seasonal and annual greenhouse gas fluxes were similar across all treatments; however, yield-scaled global warming potential (Mg CO2 eq Mg grain−1) was lower in CAWT (2.1–3.1) and CA + F (1.9–2.3) than conventional practice (1.9–8.3), averaging 62 and 68 % of the emission intensity of conventional practice, respectively. The findings demonstrate that CA can deliver benefits consistent with the objectives of CSA for farmers in this region, particularly when soil nitrogen limitation is alleviated, providing other constraints to adoption are removed.


Goenster et al. 2015. Gaseous emissions and soil fertility of homegardens in the Nuba Mountains, Sudan

Goenster, S., Wiehle, M., Predotova, M., Gebauer, J., Ali, A. M., and Buerkert, A.: Gaseous emissions and soil fertility of homegardens in the nuba mountains, sudan, J. Plant Nutr. Soil Sci., 178, 413-424, 10.1002/jpln.201400292, 2015.


Intensification of homegardens in the Nuba Mountains may lead to increases in C and nutrient losses from these small-scale land-use systems and potentially threaten their sustainability. This study, therefore, aimed at determining gaseous C and N fluxes from homegarden soils of different soil moisture, temperature, and C and N status. Emissions of CO2, NH3, and N2O from soils of two traditional and two intensified homegardens and an uncultivated control were recorded bi-weekly during the rainy season in 2010. Flux rates were determined with a portable dynamic closed chamber system consisting of a photo-acoustic multi-gas field monitor connected to a PTFE coated chamber. Topsoil moisture and temperature were recorded simultaneously to the gas measurements. Across all homegardens emissions averaged 4,527 kg CO2-C ha−1, 22 kg NH3-N ha−1, and 11 kg N2O-N ha−1 for the observation period from June to December. Flux rates were largely positively correlated with soil moisture and predominantly negatively with soil temperature. Significant positive, but weak (rs < 0.34) correlations between increasing management intensity and emissions were noted for CO2-C. Similarly, morning emissions of NH3 and increasing management intensity were weakly correlated (rs  = 0.17). The relatively high gaseous C and N losses in the studied homegardens call for effective management practices to secure the soil organic C status of these traditional land-use systems.

Hickman et al. 2015. A potential tipping point in tropical agriculture: Avoiding rapid increases in nitrous oxide fluxes from agricultural intensification in kenya

Hickman, J. E., Tully, K. L., Groffman, P. M., Diru, W., and Palm, C. A. C. J. G.: A potential tipping point in tropical agriculture: Avoiding rapid increases in nitrous oxide fluxes from agricultural intensification in Kenya, Journal of Geophysical Research: Biogeosciences, doi: 10.1002/2015jg002913, 10.1002/2015jg002913, 2015.


There are national and regional efforts aimed at increasing fertilizer use in sub-Saharan Africa, where nitrogen (N) inputs must be increased by an order of magnitude or more to reach recommended rates. Fertilizer inputs increase N availability and cycling rates and subsequently emissions of nitrous oxide (N2O), a powerful greenhouse gas and the primary catalyst of stratospheric ozone depletion. We established experimental maize (Zea mays L.) plots in western Kenya to quantify the relationship between N inputs and N2O emissions. Mean N2O emissions were marginally, but not significantly, better described by an exponential model relating emissions to N input rate in 2011; in 2012, an exponential relationship provided the best fit compared to linear and other nonlinear models. Most N2O fluxes occurred during the 30 days following the second fertilizer application. Estimates of fertilizer N lost as N2O annually were well below the 1% Intergovernmental Panel on Climate Change default emission factor, ranging from 0.07% to 0.11% in 2011 and from 0.01% to 0.09% in 2012. In both years, the largest impact on annual N2O emissions occurred when inputs increased from 100 to 150 kg N ha−1: fluxes increased from 203 to 294 g N2O-N ha−1 yr−1 in 2011 and from 168 to 254 kg N ha−1 in 2012. Our results suggest that exponential emission responses are present in tropical systems and that agricultural intensification in western Kenya may be managed for increasing crop yields without immediate large increases in N2O emissions if application rates remain at or below 100 kg N ha−1.

Sommer et al. 2015. Nitrogen dynamics and nitrous oxide emissions in a long-term trial on integrated soil fertility management in western Kenya

Sommer, R., Mukalama, J., Kihara, J., Koala, S., Winowiecki, L., and Bossio, D.: Nitrogen dynamics and nitrous oxide emissions in a long-term trial on integrated soil fertility management in western kenya, Nutrient Cycling in Agroecosystems, 10.1007/s10705-015-9693-6, 2015.


Integrated soil fertility management (ISFM) is a concept that includes the management of organic matter in smallholder farming systems for sustainable intensification. To determine whether ISFM is also eco-efficient, we measured and simulated nitrogen (N)-dynamics and nitrous oxide (N2O) emissions in an ISFM long-term maize trial in Western Kenya. The total annual N-balance averaged over 10.5 years was negative for all continuous maize treatments that received only inorganic N-fertilizer. The N-balance was zero or positive when maize was grown in rotation with the green manure cover crop, Tephrosia candid, and/or to which 4 Mg ha−1 season−1 farm yard manure (FYM) added. These results thus substantiate the importance of organic matter management in tropical ecosystems. They also underpin that mineral N-fertilizer application alone does not guarantee agro-ecosystem sustainability, which should be considered in fertilizer (subsidy) policies. Treatments that included Tephrosia and FYM application emitted the largest amounts of N2O. Highest emissions (12.0 kg N2O–N ha−1) were simulated for the maize–Tephrosia rotation to which FYM and 30 kg ha−1 of mineral fertilizer N was added and 2 Mg ha−1 maize stovers retained. Such treatments had the highest N-emission intensity. The slope of the linear regression equation describing the N2O emission–N-input relationship of all considered treatments (0.023) was twice as high as the IPCC-Tier-1 emission factor. Maize–Tephrosia treatments had the highest seasonal maize yields. These were, however, not high enough to compensate for the inclusion of Tephrosia into the system as compared to growing maize continuously, compromising adoption by smallholder farmers.

Valentini et al., 2014. A full greenhouse gases budget of Africa: synthesis, uncertainties, and vulnerabilities

Valentini, R., Arneth, A., Bombelli, A., Castaldi, S., Cazzolla Gatti, R., Chevallier, F., Ciais, P., Grieco, E., Hartmann, J., Henry, M., 2014. A full greenhouse gases budget of Africa: synthesis, uncertainties, and vulnerabilities. Biogeosciences 11, 381-407.

This paper, developed under the framework of the RECCAP initiative, aims at providing improved estimates of the carbon and GHG (CO2, CH4 and N2O) balance of continental Africa. The various components and processes of the African carbon and GHG budget are considered, existing data reviewed, and new data from different methodologies (inventories, ecosystem flux measurements, models, and atmospheric inversions) presented. Uncertainties are quantified and current gaps and weaknesses in knowledge and monitoring systems described in order to guide future requirements. The majority of results agree that Africa is a small sink of carbon on an annual scale, with an average value of −0.61±0.58 PgC yr−1. Nevertheless, the emissions of CH4 and N2O may turn Africa into a net source of radiative forcing in CO2 equivalent terms. At sub-regional level, there is significant spatial variability in both sources and sinks, due to the diversity of biomes represented and differences in the degree of anthropic impacts. Southern Africa is the main source region; while central Africa, with its evergreen tropical forests, is the main sink. Emissions from land-use change in Africa are significant (around 0.32±0.05 PgC yr−1), even higher than the fossil fuel emissions: this is a unique feature among all the continents. There could be significant carbon losses from forest land even without deforestation, resulting from the impact of selective logging. Fires play a significant role in the African carbon cycle, with 1.03±0.22 PgC yr−1 of carbon emissions, and 90% originating in savannas and dry woodlands. A large portion of the wild fire emissions are compensated by CO2 uptake during the growing season, but an uncertain fraction of the emission from wood harvested for domestic use is not. Most of these fluxes have large interannual variability, on the order of ±0.5 PgC yr−1 in standard deviation, accounting for around 25% of the year-toyear variation in the global carbon budget. Despite the high uncertainty, the estimates provided in this paper show the important role that Africa plays in the global carbon cycle, both in terms of absolute contribution, and as a key source of interannual variability.

Nyamadzawo et al., 2014. Nitrous oxide and methane emissions from cultivated seasonal wetland (dambo) soils with inorganic, organic and integrated nutrient management

Nyamadzawo, G., Wuta, M., Nyamangara, J., Smith, J., Rees, R., 2014. Nitrous oxide and methane emissions from cultivated seasonal wetland (dambo) soils with inorganic, organic and integrated nutrient management. Nutrient Cycling in Agroecosystems 100, 161-175.

In many smallholder farming areas southern Africa, the cultivation of seasonal wetlands (dambos) represent an important adaptation to climate change. Frequent droughts and poor performance of rain-fed crops in upland fields have resulted in mounting pressure to cultivate dambos where both organic and inorganic amendments are used to sustain crop yields. Dambo cultivation potentially increases greenhouse gas (GHG) emissions. The objective of the study was to quantify the effects of applying different rates of inorganic nitrogen (N) fertilisers (60, 120, 240 kg N ha−1) as NH4NO3, organic manures (5,000, 10,000 and 15,000 kg ha−1) and a combination of both sources (integrated management) on GHG emissions in cultivated dambos planted to rape (Brassica napus). Nitrous oxide (N2O) emissions in plots with organic manures ranged from 218 to 894 µg m−2 h−1, while for inorganic N and integrated nutrient management, emissions ranged from 555 to 5,186 µg m−2 h−1 and 356–2,702 µg m−2 h−1 respectively. Cropped and fertilised dambos were weak sources of methane (CH4), with emissions ranging from −0.02 to 0.9 mg m−2 h−1, while manures and integrated management increased carbon dioxide (CO2) emissions. However, crop yields were better under integrated nutrient management. The use of inorganic fertilisers resulted in higher N2O emission per kg yield obtained (6–14 g N2O kg−1 yield), compared to 0.7–4.5 g N2O kg−1 yield and 1.6–4.6 g N2O kg−1 yield for organic manures and integrated nutrient management respectively. This suggests that the use of organic and integrated nutrient management has the potential to increase yield and reduce yield scaled N2O emissions.

Masaka et al., 2014. Nitrous oxide emissions from wetland soil amended with inorganic and organic fertilizers

Masaka, J., Nyamangara, J., Wuta, M., 2014. Nitrous oxide emissions from wetland soil amended with inorganic and organic fertilizers. Archives of Agronomy and Soil Science 60, 1363-1387.

Agricultural soils are a primary source of anthropogenic trace gas emissions, and the subtropics contribute greatly, particularly since 51% of world soils are in these climate zones. A field experiment was carried out in an ephemeral wetland in central Zimbabwe in order to determine the effect of cattle manure (1.36% N) and mineral N fertilizer (ammonium nitrate, 34.5% N) application on N2O fluxes from soil. Combined applications of 0 kg N fertilizer + 0 Mg cattle manure ha−1 (control), 100 kg N fertilizer + 15 Mg manure ha−1 and 200 kg N fertilizer + 30 Mg manure ha−1 constituted the three treatments arranged in a randomized complete block design with four replications. Tomato and rape crops were grown in rotation over a period of two seasons. Emissions of N2O were sampled using the static chamber technique. Increasing N fertilizer and manure application rates from low to high rates increased the N2O fluxes by 37–106%. When low and high rates were applied to the tomato and rape crops, 0.51%, 0.40%, and 0.93%, 0.64% of applied N was lost as N2O, respectively. This implies that rape production has a greater N2O emitting potential than the production of tomatoes in wetlands.

Fan et al., 2014. Modeling pulsed soil respiration in an African savanna ecosystem.

Fan, Z., Neff, J.C., Hanan, N.P., 2014. Modeling pulsed soil respiration in an African savanna ecosystem. Agricultural and Forest Meteorology 200, 282-292.

Savannas cover 60% of the African continent and play an important role in the global carbon (C) emissions from fire and land use. To better characterize the biophysical controls over soil respiration in these settings, half-hourly observations of volumetric soil–water content, temperature, and the concentration of carbon dioxide (CO2) at different soil depths were continually measured from 2005 to 2007 under trees (“sub-canopy”) and between trees (“inter-canopy”) in a savanna vegetation near Skukuza, Kruger National Park, South Africa. The measured soil climate and CO2 concentration data were assimilated into a process-based model that estimates the CO2 production and flux with coupled dynamics of dissolved organic C (DOC) and microbial biomass C. Our results show that temporal and spatial variations in CO2 flux were strongly influenced by precipitation and vegetation cover, with two times greater CO2 flux in the sub-canopy plots (∼2421 g CO2 m−2 yr−1) than in the inter-canopy plots (∼1290 g CO2 m−2 yr−1). Precipitation influenced soil respiration by changing soil temperature and moisture; however, our modeling analysis suggests that the pulsed response of soil respiration to precipitation events (known as “Birch effect”) is a key control on soil fluxes at this site. At this site, “Birch effect” contributed to approximately 50% and 65% of heterotrophic respiration or 20% and 39% of soil respiration in the sub-canopy and inter-canopy plots, respectively. These results suggest that pulsed response of respiration to precipitation events is an important component of the C cycle of savannas and should be considered in both measurement and modeling studies of carbon exchange in similar ecosystems.

Teodoru et al. 2015. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget.

Teodoru, C.R., Nyoni, F.C., Borges, A.V., Darchambeau, F., Nyambe, I., Bouillon, S., 2015. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget. Biogeosciences 12, 2431-2453.

Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. We present data on greenhouse gas (GHG: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes, as well as data that allow for characterization of sources and dynamics of carbon pools collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHG concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e., decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands as well as the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the main channel were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic of the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of the floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River, whereas low values were characteristic of more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to 2-fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced, but higher values were generally found during the dry season. Overall, both concentrations and fluxes of CO2 and CH4 were well below the median/average values for tropical rivers, streams and reservoirs reported previously in the literature and used for global extrapolations. A first-order mass balance suggests that carbon (C) transport to the ocean represents the major component (59%) of the budget (largely in the form of dissolved inorganic carbon, DIC), while 38% of the total C yield is annually emitted into the atmosphere, mostly as CO2 (98%), and 3% is removed by sedimentation in reservoirs.