Reducing uncertainty in nitrogen budgets for African livestock systems

Summary

This literature review examines nitrogen budget estimates for the African continent, highlighting how livestock systems are poorly represented due to reliance on modelled rather than observational data. The authors identify critical uncertainties arising from constant excretion rate assumptions, crude manure distribution models, and emission factors not calibrated to African conditions, and propose that future research integrate spatial data collection, crop–livestock flow quantification, and multi-pathway nitrogen loss measurements to improve continental-scale assessments.

Regional applicability

Whilst focused on Africa, this review's identification of methodological gaps in nitrogen budgeting—particularly the need for field-calibrated emission factors and improved manure management data—has relevance to United Kingdom livestock system assessments. The emphasis on integrating crop–livestock flows and multi-pathway loss quantification aligns with United Kingdom policy priorities for reducing agricultural nitrogen pollution.

Key measures

Sources and magnitudes of uncertainty in nitrogen flows, livestock density estimates, manure management fractions, emission factors, crop residue use, nitrogen loss pathways (leaching, run-off, volatilisation, greenhouse gas emissions)

Outcomes reported

The study identified major sources of uncertainty in nitrogen budgets for African livestock systems through literature review, including livestock density modelling, constant excretion rate assumptions, manure management fractions, and emission factors. It proposes frameworks for improved spatial data collection and nested systems definitions to enhance the accuracy of continental-level nitrogen budgets.

Topic tags