population has been fed by the application of chemical N fertilizer (Erisman et al.
2008). Given the increased food and biofuel demands of the growing world population, global crop production in 2050 must double compared to that of 2005; thus,
the consumption of N fertilizer could increase by as much as 2.7 times (Tilman et al.
2011; Tilman et al. 2002).
Indeed, N plays an important role in increasing grain production that provides
humans’ food including calories and proteins. However, only 10% of the N used for
food production is consumed by the human beings (Robertson and Vitousek 2009).
On average, the global crop N use efficiency (NUE) is only approximately 42–47%
(Mueller et al. 2017; Zhang et al. 2015). A substantial fraction of Nr that is lost into
the environment through emission, runoff, etc. can cause enormous adverse environmental problems such as water pollution, climate forcing, biodiversity loss, and
air pollution (Galloway et al. 2004; Zhang et al. 2015; Yu et al., 2019). Furthermore,
N pollution costs between €70 billion and €320 billion per year in the European
Union based on the damage of Nr on human health and ecosystems (Sutton et al.
2011a). Therefore, increasing crop production while decreasing environmental costs
and protecting human health is urgently needed for N management in agricultural
systems (Lassaletta et al. 2016; Li et al. 2017b; Sutton et al. 2011b; Tilman et al.
2002).
As the world’s largest developing country, China has applied approximately 30%
of the global annual production of chemical N fertilizer for crop production in
croplands (Hou et al. 2013; Huang et al. 2017). China’s grain production has
doubled over the last several decades, from 305Mt in 1978 to 621Mt in 2015
(National Bureau of Statistics of China 2016). The total chemical N fertilizer use
increased from 9.4 Tg to 29.5 Tg from 1980 to 2010 (Yan et al. 2014). Per hectare N
addition was 209, 210, and 220 kg N ha
À1 for rice, wheat, and corn, respectively, in
recent years (Chen et al. 2014). And there were much higher N application rates for
intensive double-cropping systems (550–600 kg N ha
À1 ) and some greenhouse
vegetables, >1000 kg N ha
À1 , compared to the major crops (Ju et al. 2009; Shi
et al. 2009).
A large amount of N fertilizer applied to croplands plays a vital role in ensuring
China’s food security. The relationship between the application of fertilizer and food
production is significant (Jiao et al. 2016; Zhang et al. 2012a; Zhu and Chen 2002).
However, excessive N use has resulted in a low NUE. The in-season NUE was
30–35% in the 1990s in China from field monitoring results (Zhu and Chen 2002),
and it decreased to 26–28% in 2001–2005 (Zhang et al. 2007), which was much
lower than that in America and Europe (Ladha et al. 2005). Much of the N in the
form of ammonia, nitrate, and N oxides is lost to the environment, which are
considered expensive and environmentally damaging waste in China (Guo et al.
2010; Liu et al. 2013; Wang et al. 2016; Wang and Zhao 2014).
Presently, environmental sustainability is a policy priority in China; however,
China needs to produce more grain yield to meet the demand of an increasing
population in the near future, along with a change in diet and energy needs (Miao
et al. 2011). Therefore, regulations for N to optimize benefits for food production
while minimizing damage to human health and ecosystem pollution from
298
C. Ti and X. Yan
2008). Given the increased food and biofuel demands of the growing world population, global crop production in 2050 must double compared to that of 2005; thus,
the consumption of N fertilizer could increase by as much as 2.7 times (Tilman et al.
2011; Tilman et al. 2002).
Indeed, N plays an important role in increasing grain production that provides
humans’ food including calories and proteins. However, only 10% of the N used for
food production is consumed by the human beings (Robertson and Vitousek 2009).
On average, the global crop N use efficiency (NUE) is only approximately 42–47%
(Mueller et al. 2017; Zhang et al. 2015). A substantial fraction of Nr that is lost into
the environment through emission, runoff, etc. can cause enormous adverse environmental problems such as water pollution, climate forcing, biodiversity loss, and
air pollution (Galloway et al. 2004; Zhang et al. 2015; Yu et al., 2019). Furthermore,
N pollution costs between €70 billion and €320 billion per year in the European
Union based on the damage of Nr on human health and ecosystems (Sutton et al.
2011a). Therefore, increasing crop production while decreasing environmental costs
and protecting human health is urgently needed for N management in agricultural
systems (Lassaletta et al. 2016; Li et al. 2017b; Sutton et al. 2011b; Tilman et al.
2002).
As the world’s largest developing country, China has applied approximately 30%
of the global annual production of chemical N fertilizer for crop production in
croplands (Hou et al. 2013; Huang et al. 2017). China’s grain production has
doubled over the last several decades, from 305Mt in 1978 to 621Mt in 2015
(National Bureau of Statistics of China 2016). The total chemical N fertilizer use
increased from 9.4 Tg to 29.5 Tg from 1980 to 2010 (Yan et al. 2014). Per hectare N
addition was 209, 210, and 220 kg N ha
À1 for rice, wheat, and corn, respectively, in
recent years (Chen et al. 2014). And there were much higher N application rates for
intensive double-cropping systems (550–600 kg N ha
À1 ) and some greenhouse
vegetables, >1000 kg N ha
À1 , compared to the major crops (Ju et al. 2009; Shi
et al. 2009).
A large amount of N fertilizer applied to croplands plays a vital role in ensuring
China’s food security. The relationship between the application of fertilizer and food
production is significant (Jiao et al. 2016; Zhang et al. 2012a; Zhu and Chen 2002).
However, excessive N use has resulted in a low NUE. The in-season NUE was
30–35% in the 1990s in China from field monitoring results (Zhu and Chen 2002),
and it decreased to 26–28% in 2001–2005 (Zhang et al. 2007), which was much
lower than that in America and Europe (Ladha et al. 2005). Much of the N in the
form of ammonia, nitrate, and N oxides is lost to the environment, which are
considered expensive and environmentally damaging waste in China (Guo et al.
2010; Liu et al. 2013; Wang et al. 2016; Wang and Zhao 2014).
Presently, environmental sustainability is a policy priority in China; however,
China needs to produce more grain yield to meet the demand of an increasing
population in the near future, along with a change in diet and energy needs (Miao
et al. 2011). Therefore, regulations for N to optimize benefits for food production
while minimizing damage to human health and ecosystem pollution from
298
C. Ti and X. Yan