Toward a nitrogen footprint calculator for Tanzania

We present the first nitrogen footprint model for a developing country: Tanzania. Nitrogen (N) isa crucial element for agriculture and human nutrition, but in excess it can cause seriousenvironmental damage. The Sub-Saharan African nation of Tanzania faces a two-sided nitrogenproblem: while there is not enough soil nitrogen to produce adequate food, excess nitrogen thatescapes into the environment causes a cascade of ecological and human health problems. Toidentify, quantify, and contribute to solving these problems, this paper presents a nitrogenfootprint tool for Tanzania. This nitrogen footprint tool is a concept originally designed for theUnited States of America (USA) and other developed countries. It uses personal resourceconsumption data to calculate a per-capita nitrogen footprint. The Tanzania N footprint tool is aversion adapted to reflect the low-input, integrated agricultural system of Tanzania. This isreflected by calculating two sets of virtual N factors to describe N losses during food production:one for fertilized farms and one for unfertilized farms. Soil mining factors are also calculated forthe first time to address the amount of N removed from the soil to produce food. The averageper-capita nitrogen footprint of Tanzania is 10 kg N yr1. 88% of this footprint is due to foodconsumption and production, while only 12% of the footprint is due to energy use. Although91% of farms in Tanzania are unfertilized, the large contribution of fertilized farms to N lossescauses unfertilized farms to make up just 83% of the food production N footprint. In adeveloping country like Tanzania, the main audiences for the N footprint tool are communityleaders, planners, and developers who can impact decision-making and use the calculator to planpositive changes for nitrogen sustainability in the developing world.JRC.D.5-Food Securit