Work package numberWP3Lead beneficiaryKarlsruhe Institute of Technology (KIT)
TitleNatural and anthropogenic emissions, livestock and agriculture  
Start month1 (Feb 2020)End month48 (Jan 2024)


WP3 deals with the establishment of N flows from site, to regional and continental scales with regards to fluxes of the N gaseous compounds NO, N2O, NH3 and N2 (incl. both denitrification N losses as well as biological N2 fixation), and leaching of N compounds from soils (mainly nitrate) with regard to

  • natural and semi-natural systems (e.g. pastoral systems of the Sahel),
  • agriculture (livestock systems and cropping systems) and
  • anthropogenic emissions and losses due to energy generation and waste disposal and management

The aim is to synthesize current knowledge, using as well information from work package 2 (deposition, lateral N transport and export of N by rivers), to identify knowledge and research gaps at various scales, identify opportunities and methods for extrapolating site and regional studies to regional and continental scale and to support individual studies by partners, both experimental as well as modelling, by staff exchange. WP3 will finally deliver consolidated environmental N flows of terrestrial systems in
Africa on various spatial-temporal scales, identify hotspots and coldspots of N flows and an assessment of uncertainty of N flows and research demands. In close cooperation with work package 2 N budgets for selected watersheds (e.g. Nile, Zambezi) and the entire continent using the net anthropogenic nitrogen input (NANI) approach will be developed.

The NANI approach is an effective method to assess human-induced N inputs to landscapes or even larger regions and to evaluate their potential impacts on riverine export from large basins. The NANI model approach is based on the calculation of the sum of atmospheric N deposition, fertilizer N application, agricultural N2 fixation and net food and feed imports. Sewage and animal wastes do not necessarily need to be included as inputs to a given study region as nitrogen in waste is not newly fixed and mostly not imported, but represent a pathway of redistribution or recycling of nitrogen within a region.

Description of work and role of partners

Task 3.1: Literature review, study selection and NANI (lead: Karlsruhe Institute of Technology (KIT))

The Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU) of KIT the  will carry out a literature review and a synthesis of current knowledge on N flows in terrestrial systems on various spatial-temporal scales. This review will allow identifying relevant catchments and watershed for which a NANI is feasible. Envisaged is specifically the Nile catchment as for the upper Nile, i.e. the Lake Victoria watershed, a NANI has recently been done. The KIT staff has long-term experiences in working in Africa and in establishing site, regional and continental N balances
for livestock and cropping system. KIT is mainly active in East- and West-Africa, but is also networked to other regions in Africa. The expertise of KIT staff involved are covering all relevant fields from measurement to modeling and integration.

Task 3.2 : N flows in natural and semi-natural systems (including pastoral systems in semi-arid environments such as the Sahel) (lead: Toulouse III – Paul Sabatier University (UT3))

The study of nitrogen compound exchanges in tropical ecosystems is of specific interest: high temperatures, associated with drastic changes in soil moisture when dry and wet seasons alternate, lead to an important seasonality in deposition, emission and transformation of nitrogen in soils. Pulses emissions occur when dry soils are wetted by the first rains (especially in the Sahel region), due to the rapid decomposition and subsequent mineralization of organic matter. In this task we propose to give an insight in N cycle (and its connection to C and P cycles) in tropical African ecosystems by analyzing transformation mechanisms in the soil, linked to reactive N compound exchanges between the terrestrial
surface and the atmosphere, and define the role of natural emissions (and their anthropogenic forcing by livestock impact) on the N atmospheric burden. Microbial processes in the soil, their link with soil respiration, N uptake by vegetation, will be focused on. This task will revisit existing modelling, satellite and in situ observations studies of natural N emissions in Africa, especially for NO, NH3, N2O and CO2, and particles in the nutrient budget (N and P), connected to deposition fluxes developed in Task 2.4 under work package 2. Site scale studies will be performed for example in the Sahel, where past studies by UT3 Paul Sabatier have measured greenhouse and reactive gas emissions, and at Yangambi site, central Congo where a flux tower is equipped by the University of Ghent to monitor greenhouse gas emissions. Taking into account the strong seasonality and the large spatial variability of these emissions is of prime importance to propose an interactive interface between the surface and the atmosphere.

Task 3.3 : N flows in livestock systems with a specific emphasis on manure management (lead: International Livestock Research Institute (ILRI)

Within this task, the Aarhus University and ILRI will collect existing data on N flows in dominant livestock systems in East Africa and also if possible in other regions of Africa (in collaboration with the Pastoralisme Conseil (PASTOC)), and summarize available knowledge on N flows as driven by livestock production. A specific focus will thereby be given on the one hand on to feed availability and feeding systems and on the other hand on manure and manure management, with a link to agricultural and social practices. Both factors, including livestock numbers, will be used to constrain input-output balances of N in livestock production systems. Information will be spatially explicited using e.g. information as provided by the LivestockWiki, so that hot spots of N use and N release due to livestock production can be identified. The International Livestock Research Institutes Mazingira Centre located in Nairobi is a stateof-the-art environmental and education laboratory. The Center’s mandate is to derive baseline greenhouse gas emissions and nitrogen flows from agricultural production systems in developing countries. Thereby a strong focus is given to East Africa and livestock production systems in that region. PASTOC will bring its expertise in livestock systems of West Africa.

Task 3.4: N flows in cropping and agro-forestry systems (lead: University of Ghent)

Smallholder agriculture is key driver of many African countries economies. Synthetic N use is still low in this kind of agricultural practices so that most countries have not been able to meet the fertilizer target of 50 kg nutrients ha-1 advocated in the 2006 Abuja declaration. As over 65% of the smallholder farmers in Africa do not use fertilizer, 75% of the agricultural soils are affected by nutrient depletion. In this task we will revisit current knowledge and identify trends in N use and we will provide estimates on N inputs by legumes as part of cropping systems. Agricultural practices, manure imports and NUE modifications will be investigated. The N gains due to fixation by legume crops and N losses due to crop residue management, including crop waste burning will be targeted. The use of fire for crop clearing
and crop residue burning will be further analyzed for a better understanding of the social underlying causes and the future evolution of this practice. Based on agricultural statistics (e.g. FAO database) and site, regional and national studies, gathered by participating organizations (Justus Liebig University Giessen, International Institute of Tropical Agriculture, University of Ghent in Belgium, Institute of Agricultural Research & Training in NigeriaToulouse III – Paul Sabatier University) we aim at estimating total N balances of cropping systems at regional scale, e.g. as a contribution to the NANI approach.

Task 3.5: Anthropogenic environmental N losses due to energy generation, transport, and waste management (lead: Toulouse III Paul Sabatier University)

This task will deal with the impact of human activities on nitrogen losses in the environment. There are still many gaps and uncertainties in the existing emission inventories linked with combustions. Regional scale inventories of combustion sources will be developed for the present .The contribution of domestic fires, traffic, industries, waste burning and flaring emissions to NOx and NH3 emissions will be estimated according to the work of Keita et al. (2018), dealing with African emission inventories for the years 1990-2015. In the framework of the INSA MSCA-RISE project, such inventories will be first extended to the years 2016-2020. Second, thanks to a parallel program called PASMU with planned experiments in 2019 and 2020, emission factor values of NOx and NH3 used in such inventories will be improved from new measurements. The contribution of biomass burning to NOx and NH3 emissions will be also studied. Main uncertainties dealing with vegetation parameterization in emission calculation algorithms from satellite data and with emission factors values will be improved benefiting from FAO project to be undertaken in the 2019-2020 dry season. Then biomass burning inventories will be developed for the years 2015-2020. Finally emission inventories for combustion sources will
be developed for scenarios in 2050 using the methodology developed in Liousse et al. (2014). Another important issue in the rapidly growing regions of high density of population relates to high nitrogen loads rejected in natural environment due to the poor treatment (less than 8% in quantity) of effluents from the industrial and municipal facilities. Poor land use practices have also increased the transport and loss of nitrogen and phosphorus from the agricultural land to the rivers, lakes and lagoons. High losses of nitrogen and phosphorus have resulted on one side to the decline in soil nutrients and
crop productivity and on the other side to the deterioration of water quality in aquatic bodies. More work is needed to understand processes regulating N transformations along the transport from terrestrial to aquatic systems, and to quantify the final N load in the environment. This is the first step in the view to evaluate the impact of those transfer on the ecosystem and human health and possibly mitigate those effects.

Description of deliverables

D3.1: Training manual for implementing NANI approaches and methods for assessing N fluxes via
hydrological and gaseous pathways (month 22, Nov 2021)

D3.2: Data compilation from literature and synthesis of current knowledge (month 26, March 2022)

D3.3: Nitrogen species (NOx, NH3) emission inventory for the 2015-2020 period and beyond (combustions) (month 36, Jan 2023)

D3.4: Report on N balances for selected regions in Africa to be included in the policy brief (month 44, Sept 2023)

D3.5: Report on NANI for major continental watersheds (month 46, Nov 2023)

D3.6: Quantification of nitrogen loads and transfers from terrestrial to aquatic systems (waste water) (month 46, Nov 2023)