Improving Nitrogen Use Efficiency in the Chinese Food Chain to Reduce Air and Water Pollution

Mengru Wanga,b, Lin Mab, Maryna Strokala,c, Yanan Chuc, Ang Lia,b, Carolien Kroezea

a Water Systems and Global Change Group, Wageningen University, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands, https://www.wageningenur.nl/en/Persons/Mengru-M-Mengru-Wang-MSc.htm, [email protected]

b Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 286 Huaizhong Road, Shijiazhuang 050021, China

c Environmental Systems Analysis Group, Wageningen University, Droevendaalsesteeg 4, 6708 PB Wageningen, The Netherlands

Abstract

Nitrogen (N) use efficiency is low in Chinese agriculture. This results in large N losses to air and water. We aim to explore effective nutrient management options to increase N use efficiencies in the food chain, and thus to reduce N losses to the environment for 2020 and 2050 in China by scenario analysis. Three scenarios were developed and implemented assuming Business As Usual (BAU) trends, Zero Fertilizer (ZF) growth from 2020, and Improved Nutrient Management (INM). N use efficiencies in agriculture, and N losses were quantified using the NUFER (NUtrient flows in Food chains, Environment and Resources use) model. Results show that N use efficiency in 2013 is low at about 20%. Thus the losses to air (14 Tg of N) and water (12 Tg of N) are high in 2013. The N use efficiencies will likely remain at their low 2013 levels in 2020 and 2050 under BAU, resulting in large increase in N losses to air and water between 2013 and 2050. INM is projected to increase N use efficiency to 33% in 2050. N losses to water in 2050 are almost half of that in 2013, and to air are 20% lower. Scenario ZF incorporates recent Chinese policies aiming at a zero growth in synthetic fertilizer use from the year 2020 onwards. ZF is projected to be much less effective than INM. We conclude that nutrient management that simultaneously reduces fertilization, improves manure management, and reduces nutrient excretion in animal manure, is needed for Chinese agriculture.