Calculating Your Country's N footprint
Are you interested in calculating your country's nitrogen footprint? This page explains some of the data requirements and what is required for the calculation. The N Footprint tool is country-specific and requires data from multiple sources (national and international) to determine the average amount of reactive nitrogen lost to the environment as a result of personal consumption patterns in a given country. In the online N-Calculator, the average per capita N footprint is scaled based on the user's lifestyle choices, such as their food choices, transport mode, and household energy use.
The N-Calculator focuses on four main consumption areas. More information can be found below for each sector.
Goods & services
The food nitrogen footprint has two components: food consumption and food production. The food consumption nitrogen footprint is the amount of nitrogen contained in the food consumed, which is ultimately lost as human waste. The food consumption N footprint is calculated using country-specific food supply and food waste data from FAOSTAT. Before being lost to the environment, the reactive nitrogen in human waste may be removed from the wastewater stream or denitrified to N2 at a sewage treatment facility. Sewage treatment factors are collected to account for any N removal.
The food production nitrogen footprint is the reactive nitrogen lost to the environment during the food production process. This also referred to as virtual nitrogen. The food production N footprint is calculated using virtual N factors, which are country-specific and are calculated for major food categories. These factors account for each stage of the food production process (e.g., fertilizer application, processing, food waste). The losses are summed and divded by the N contained in the final consumed food product. Data requirements for calculating your country's virtual N factors include crop-specific N uptake factors, processing losses, and livestock feed conversion ratios. If your country imports a significant proportion of its food, then the virtual N factors of the producing country should also be accounted for in your country's per capita N footprint. N losses from energy use during food production are accounted for through a "top-down" approach: an environmentally-extended input-output analysis that allocates national N emissions to personal consumption patterns.
Key data requirements for the food nitrogen footprint are the country's food protein consumption by food type, rate of food waste, and food production losses (i.e., virtual N factors).
Energy (housing and transport):
The housing and transport N footprints account for the N emitted from fossil fuel combustion associated with housing energy and transportation, respectively. Data requirements for these sectors include average energy consumption (e.g., household electricity used per month, average kilometers traveled by car) and the associated N emission factors. The energy consumption data and associated emission factors are used to calculate the "bottom-up" portion of the energy N footprint. A small portion of the energy N footprint is calculated through a "top-down" approach: an environmentally-extended input-output analysis.
Goods and services:
The smallest sector, the goods and services N footprint accounts for the average per capita N released to produce goods (e.g., clothing) and provide services (e.g., hospital services) in a country. This portion of the N footprint is calculated through an environmentally-extended input-output analysis.
A note on uncertainty:
It is important to note that the N-Calculator calculates the average per capita N footprint for a country. Food production N losses and other N emission factors can vary throughout a country. The N-Calculator aims to present the average situation to help communicate nitrogen pollution issues to consumers.
Would you like to calculate your country's N footprint?
We work directly with partners in countries to develop their country-specific N-Calculator. The country partner typically is expected to lead the data collection because many of a country's data sources are available through national databases, and the country partner will be most familiar with nitrogen dynamics in their country. Our team can provide the N-Calculator tools, support during the data collection, and a final review of the data. Depending on the complexity of a country's nitrogen dynamics, our team may require funding to assist you in the development of your country's N-Calculator.
For more information, please contact the N-Print team at Allison.Leach @ unh.edu