Nitrogen budget and critical load estimate in a semi-arid grazed ecosystem

A nitrogen budget was calculated in a semi-arid grazed ecosystem in Senegal (Dahra site), including nitrogen inputs (wet and dry deposition, biological nitrogen fixation (BNF)) and outputs (natural emissions of NO, N2O, volatilization of NH3 from animal excreta, anthropogenic emissions of NO and NH3 from fires, nitrogen uptake by trees and animals, soil leaching). Nitrogen soil leaching was measured in situ for the first time in the Sahel. Calculated nitrogen inputs did not exceed the critical load estimated for this specific ecosystem.