Toward a nitrogen footprint calculator for Tanzania

Abstract

We present the first nitrogen footprint model for a developing country: Tanzania. Nitrogen (N) is\na crucial element for agriculture and human nutrition, but in excess it can cause serious\nenvironmental damage. The Sub-Saharan African nation of Tanzania faces a two-sided nitrogen\nproblem: while there is not enough soil nitrogen to produce adequate food, excess nitrogen that\nescapes into the environment causes a cascade of ecological and human health problems. To\nidentify, quantify, and contribute to solving these problems, this paper presents a nitrogen\nfootprint tool for Tanzania. This nitrogen footprint tool is a concept originally designed for the\nUnited States of America (USA) and other developed countries. It uses personal resource\nconsumption data to calculate a per-capita nitrogen footprint. The Tanzania N footprint tool is a\nversion adapted to reflect the low-input, integrated agricultural system of Tanzania. This is\nreflected by calculating two sets of virtual N factors to describe N losses during food production:\none for fertilized farms and one for unfertilized farms. Soil mining factors are also calculated for\nthe first time to address the amount of N removed from the soil to produce food. The average\nper-capita nitrogen footprint of Tanzania is 10 kg N yr1. 88% of this footprint is due to food\nconsumption and production, while only 12% of the footprint is due to energy use. Although\n91% of farms in Tanzania are unfertilized, the large contribution of fertilized farms to N losses\ncauses unfertilized farms to make up just 83% of the food production N footprint. In a\ndeveloping country like Tanzania, the main audiences for the N footprint tool are community\nleaders, planners, and developers who can impact decision-making and use the calculator to plan\npositive changes for nitrogen sustainability in the developing world.