fertilizer, and an optimal N rate based on soil N tests, could significantly increase
crop production and reduce Nr losses in China (Xia et al. 2017a). Even the simple
practice of using a urease inhibitor (e.g., Limus) application can lead to a yield
increase of 0–5%, NUE increase of 13–14%, and NH 3 loss decrease by 80–84%
(Li et al. 2015, 2017a). Otherwise, application of livestock manure in croplands to
substitute chemical N fertilizer significantly increased crop yield and annual SOC
sequestration while reducing Nr losses via NH 3 emission, N leaching, and N runoff
(Xia et al. 2017b).
Much research has focused on technological innovation to improve NUE in crop
production, but the socioeconomic constraints are at present poorly understood.
Fertilizer use on a per area basis sharply decreased with the increase in farm size,
and the crop yield is higher at large-scale farms compared to that in smallholder
farms in China. The high labor cost suggests a low machinery level at smallholder
farms, which inhibits the application of precise fertilization technologies and management based on scientific knowledge (Ju et al. 2016). Considering the benefits of
N fertilizer use to ecological and social systems based on 156 farm sites with five
different N levels, agronomically, privately, ecologically, and socially optimized,
Ying et al. (2017) indicated that N management using the ecologically and socially
optimized N rate provides a win-win opportunity with a significant increase in grain
yield while reducing Nr loss of wheat; it should be prioritized in agricultural research
and practice.
In fact, to seek food and environmental security, the central government of China
has officially established a series of programs, projects, and regulations to enhance
NUE and reduce environmental risk in search of sustainable agriculture development. For example, a soil testing and fertilizer recommendation (STFR) program
used to decrease N fertilizer application was implemented by the Ministry of
Agriculture (MOA) since the late 1990s. Following implementation of the program,
approximately 66.7 million hectares of croplands had been incorporated by 2009. An
announcement of “Zero Increase Action Plan for Fertilizer Use” was launched in
2015; it is reasonable to be confident that the NUE for crop production in China
could be further increased. According to this announcement, China plans to develop
precision agriculture, adjust the fertilizer consumption structure, and use more
organic fertilizer to replace chemical fertilizers. Based on these policies, research
has shown that under a no more chemical fertilizer input scenario from 2020, NUE
would be a few percentage points higher than it is in the current scenario, but its
effect on nutrient pollution reduction was not effective in reducing nutrient pollution
in China (Wang et al. 2017).
13.5 Summary/Policy Implications
The issue of N fertilizer overuse has long been recognized. N management practices
and mitigate strategies should be considered when policy-makers wish to increase
the NUE or decrease N fertilizer use. More regulations need to be developed and
13 Nitrogen Regulation in China’s Agricultural Systems
305
crop production and reduce Nr losses in China (Xia et al. 2017a). Even the simple
practice of using a urease inhibitor (e.g., Limus) application can lead to a yield
increase of 0–5%, NUE increase of 13–14%, and NH 3 loss decrease by 80–84%
(Li et al. 2015, 2017a). Otherwise, application of livestock manure in croplands to
substitute chemical N fertilizer significantly increased crop yield and annual SOC
sequestration while reducing Nr losses via NH 3 emission, N leaching, and N runoff
(Xia et al. 2017b).
Much research has focused on technological innovation to improve NUE in crop
production, but the socioeconomic constraints are at present poorly understood.
Fertilizer use on a per area basis sharply decreased with the increase in farm size,
and the crop yield is higher at large-scale farms compared to that in smallholder
farms in China. The high labor cost suggests a low machinery level at smallholder
farms, which inhibits the application of precise fertilization technologies and management based on scientific knowledge (Ju et al. 2016). Considering the benefits of
N fertilizer use to ecological and social systems based on 156 farm sites with five
different N levels, agronomically, privately, ecologically, and socially optimized,
Ying et al. (2017) indicated that N management using the ecologically and socially
optimized N rate provides a win-win opportunity with a significant increase in grain
yield while reducing Nr loss of wheat; it should be prioritized in agricultural research
and practice.
In fact, to seek food and environmental security, the central government of China
has officially established a series of programs, projects, and regulations to enhance
NUE and reduce environmental risk in search of sustainable agriculture development. For example, a soil testing and fertilizer recommendation (STFR) program
used to decrease N fertilizer application was implemented by the Ministry of
Agriculture (MOA) since the late 1990s. Following implementation of the program,
approximately 66.7 million hectares of croplands had been incorporated by 2009. An
announcement of “Zero Increase Action Plan for Fertilizer Use” was launched in
2015; it is reasonable to be confident that the NUE for crop production in China
could be further increased. According to this announcement, China plans to develop
precision agriculture, adjust the fertilizer consumption structure, and use more
organic fertilizer to replace chemical fertilizers. Based on these policies, research
has shown that under a no more chemical fertilizer input scenario from 2020, NUE
would be a few percentage points higher than it is in the current scenario, but its
effect on nutrient pollution reduction was not effective in reducing nutrient pollution
in China (Wang et al. 2017).
13.5 Summary/Policy Implications
The issue of N fertilizer overuse has long been recognized. N management practices
and mitigate strategies should be considered when policy-makers wish to increase
the NUE or decrease N fertilizer use. More regulations need to be developed and
13 Nitrogen Regulation in China’s Agricultural Systems
305