Toward sustainable development goals: Virtual nitrogen factors and nitrogen footprint in Thailand

Abstract

The nitrogen (N) footprint is an index of quantitative determination of nitrogen emissions (all species of N except N2) or the anthropogenic release of reactive nitrogen (Nr). This work evaluates the first assessment of the Nr in Thailand which covers the major human activities, including food, housing, transportation, goods, and services. This study calculated specific virtual nitrogen factors (VNFs) of eight food categories: cereal (rice), vegetable (baby corn), fruit (pineapple), poultry, pork, beef, milk and egg. The system boundary along the food production and consumption chains starts from N fertiliser applied to crops and ends with sewage treatment. Effect of the international trade of food was considered. The results showed that the average per capita N footprint of consumption based on international and national trading in Thailand was 19.07 and 19.33 kg Ncapita−1 yr−1 in 2017. The footprint was dominated by food (11.08−11.35 kg Ncapita−1 yr−1), followed by the sectors of transportation (6.83 kg Ncapita−1 yr−1), housing (0.79 kg Ncapita−1 yr−1), and the goods & services (0.37 kg Ncapita−1 yr−1). 58.13−58.70% of food N consumption in Thailand is from crops. Among crops, rice consumption and production was the major contributor to high food N footprint (34.97−35.26%), followed by poultry (32.65−33.13%). The high domestic consumption and international trade values resulted in the highest rice N footprint (3.87−4.00 kg N capita−1 yr−1), which was moderately 1.40−1.67 times greater than that of other countries (Austria, Australia, the US, and the UK). Thailand has a high value of N footprint for poultry (3.62−3.76 kg N capita−1 yr−1) because of less efficiency of fertiliser use, which was leached to the soil during plantation. The VNFs for crops were 1.10−24.48 while that of livestock products were 0.59−24.77. Similarly, the high VNFs of food crops were caused by a small edible portion of baby corn and pineapple (25.0.7−38.2%) and the inefficiency of N fertiliser use in the production (7.17−9.63%). Our results provide the opportunities to reduce N pollution by increasing N utilisation in food and feed productions, using clean energy sources with potential for fossil energy substitution, and managing dietary structure to reduce N footprint. © 2021