Modeling Nutrient Flows in the Food Chain of China

Abstract

Increasing nitrogen (N) and phosphorus (P) inputs have greatly contributed to the increasing food production in China during the last decades, but have also increased N and P losses to the environment. The pathways and magnitude of these losses are not well quantified. Here, we report on N and P use efficiencies and losses at a national scale in 2005, using the model NUFER (NUtrient flows in Food chains, Environment and Resources use). Total amount of "new" N imported to the food chain was 48.8 Tg in 2005. Only 4.4.Tg reached households as food. Average N use efficiencies in crop production, animal production, and the whole food chain were 26, 11, and 9%, respectively. Most of the imported N was lost to the environment, that is, 23 Tg N to atmosphere, as ammonia (57%), nitrous oxide (2%), dinitrogen (33%), and nitrogen oxides (8%), and 20 Tg to waters. The total P input into the food chain was 7.8 Tg. The average P use efficiencies in crop production, animal production, and the whole food chain were 36, 5, and 7%, respectively. This is the first comprehensive overview of N and P balances, losses, and use efficiencies of the food chain in China. It shows that the N and P costs of food are high (for N 11 kg kg(-1), for P 13 kg kg(-1)). Key measures for lowering the N and P costs of food production are (i) increasing crop and animal production, (ii) balanced fertilization, and (iii) improved manure management.

International trade of animal feed: its relationships with livestock density and N and P balances at country level

“…However, output from the crop and Agroecosyst (2018) 110:197-211 207 animal production sectors used for industrial purposes, including bioenergy production, was neglected due to lack of data. The N in non-food output at country level is likely to be \ 10% and the P in non-food output is likely to be \ 20% (Ma et al 2010;Van Dijk et al 2016). Hence, our N and P balances are likely overestimates, because of the neglect of non-food output.…”

“…Estimations for China were made with the NUFER model, and for European countries with the MITERRA-Europe model. NUFER model is a static mass flow model for the whole food productionconsumption chain in China and operates at the regional level (Ma et al 2010). MITERRA-Europe model is an environmental assessment model for nutrient losses and greenhouse gases emission in EU-27 at regional and country level (Lesschen et al 2011).…”

“…Output was defined as the net food output for domestic use and the net export of food and feed, as follows from the FAO databases. The calculation procedure of output follows the one outlined by Ma et al (2010Ma et al ( , 2012. However, output from the crop and Agroecosyst (2018) 110:197-211 207 animal production sectors used for industrial purposes, including bioenergy production, was neglected due to lack of data.…”

Modelling nitrogen and phosphorus export by the Pearl River in China 1970–2050

“…China is a country with a rapid economic development and a fast growing population [13][14][15][16][17][18][19]. For example, the number of cities in China more than quadrupled and the urban population increased by over 20 times between the 1950s and 2008 [17].…”

River export of nutrients to the coastal waters of China: the MARINA model to assess sources, effects and solutions

“…Part of the available animal manure is discharged directly to water bodies or landfilled as waste (Li et al 2011a;Ma et al 2010;Ma et al 2012). Our results indicate that TN and TP inputs to land from animal manure have at least doubled since 1970 (Table 2.2).…”