Long-term dynamics of nitrogen flow in a typical agricultural and pastoral region on the Qinghai-Tibet Plateau and its optimization strategy

Food Nitrogen Footprint Increased by 35% on the Third Pole During 1998–2018

“…Mean annual precipitation reaches 486 mm, and the average annual temperature is generally between −6° and 3°C. With a total area of 546.34 billion m 3 of water resources, the plateau is the birthplace of important rivers in China, known as the “Asian water tower” (Wang, Liu, et al., 2021 ). Its excellent location and climate support the valley agriculture and livestock industry.…”

“…(1) Crop production: Fertilizer N (new N and recycled N) inputs to the CPS, and only a fraction of these inputs can be used by grain and straw to enter the next process, or denitrified into N 2 ; the remaining N is lost to the atmosphere and water when soil N is assumed to be constant (Cui et al., 2016 ). Due to the complexity of the soil N cycle and the indirect calculation of accumulated N (Cui et al., 2016 ; Wang, Liu, et al., 2021 ), the calculation of the FNF did not take N losses into the soil into account. …”

“…(1) Crop production: Fertilizer N (new N and recycled N) inputs to the CPS, and only a fraction of these inputs can be used by grain and straw to enter the next process, or denitrified into N 2 ; the remaining N is lost to the atmosphere and water when soil N is assumed to be constant (Cui et al., 2016). Due to the complexity of the soil N cycle and the indirect calculation of accumulated N (Cui et al., 2016; Wang, Liu, et al., 2021), the calculation of the FNF did not take N losses into the soil into account. $$${\mathrm{F}\mathrm{N}\mathrm{F}}_{(1)}={N}_{\mathrm{f}\mathrm{e}\mathrm{r}\mathrm{t}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{z}\mathrm{e}\mathrm{r}}+{N}_{\mathrm{B}\mathrm{N}\mathrm{F}}+{N}_{\mathrm{d}\mathrm{e}\mathrm{p}\mathrm{o}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}+{N}_{\mathrm{s}\mathrm{e}\mathrm{e}\mathrm{d}}+{N}_{\mathrm{i}\mathrm{r}\mathrm{r}\mathrm{i}\mathrm{g}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}+{N}_{\mathrm{m}\m...$$…”

“…The above studies have improved our understanding of N production from human activities, thus providing feasible strategies for N management. Due to natural factors, socioeconomic levels, and spatial differences in N sources, the FNF varies widely among regions, and few quantitative studies have been conducted on the Qinghai‐Tibet Plateau (QTP) (Wang, Liu, et al., 2021 ). Moreover, the study of N flow on the QTP is limited to the temporal scale, and lack spatial consideration or comparison.…”

“…In recent decades, from N fertilizer to crop products, feed, livestock and poultry products and household consumption, a series of N cascades have led to an increase in N losses (Gao et al., 2018 ; Li et al., 2018 ). The three systems of crop production, animal husbandry and household consumption have become the main body of the N flow research system (Gao et al., 2020 ; Wang, Cai, et al., 2021 ; Wang, Liu, et al., 2021 ). Studies have shown that the N losses caused by food‐related production and consumption are the most important contributor to China's N footprint and have become a major environmental issue (Gu et al., 2013 ).…”