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- Title
Effects of agricultural practices on nitrogen distribution in unsaturated soils.
- Authors
Wang, Jinguo; Zhang, Yuting; Yang, Fenggen; Zhao, Yanrong; Zheng, Hu
- Abstract
Nitrogen fertilizer consumption is very common in the agricultural practices. Nitrogen application could be an important source of groundwater N pollution. Normally, nitrogen can pass through the unsaturated zone to pollute the groundwater. Different agricultural practices have different cultivation methods, accordingly different fertilization and irrigation techniques. Hence, the agricultural practice determines the environment of the unsaturated zone, which subsequently determines the extent of groundwater N pollution. To verify the pollution modes and transformation mechanisms of nitrogen, both in situ and laboratory tests were conducted at four different sites to study the effects of agricultural practices on nitrogen distribution in unsaturated zones. The inorganic nitrogen in soil is extracted by potassium chloride solution, and the soil utilization form and pollution type are identified by δ15N by comparing with the known standard values. The experimental results indicate that continual fertilization and sewage irrigation in these agricultural regions were the primary sources of nitrogen in the unsaturated zone. In the soils planted with rice, δ15N–NH4+ was relatively elevated due to ammonium volatilization. In the unsaturated zone of rice–wheat rotation fields, NO3−–N and δ15N were both elevated because of manure fertilizer. Meanwhile, denitrification also occurred in the hypoxic environment due to the high soil water content.
- Subjects
NITROGEN fertilizers &; the environment; GROUNDWATER pollution; ISOTOPIC analysis; DENITRIFICATION; ZONE of aeration
- Publication
Environmental Earth Sciences, 2017, Vol 76, Issue 24, p0
- ISSN
1866-6280
- Publication type
Article
- DOI
10.1007/s12665-017-7089-4