Soluble organic nitrogen cycling in soils after application of chemical/organic amendments and groundwater pollution implications

Leyun Wang; Xilai Zheng; Feifei Tian; Jia Xin; Hui Nai

doi:10.1016/j.jconhyd.2018.08.003

Soluble organic nitrogen cycling in soils after application of chemical/organic amendments and groundwater pollution implications

J Contam Hydrol. 2018 Oct:217:43-51. doi: 10.1016/j.jconhyd.2018.08.003. Epub 2018 Aug 12.

Authors

Leyun Wang¹, Xilai Zheng², Feifei Tian¹, Jia Xin³, Hui Nai¹

Affiliations

¹ Key Laboratory of Marine Environment Science and Ecology, Ministry of Education and College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
² Key Laboratory of Marine Environment Science and Ecology, Ministry of Education and College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China. Electronic address: zhxilai@ouc.edu.cn.
³ Key Laboratory of Marine Environment Science and Ecology, Ministry of Education and College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China. Electronic address: xinj15@ouc.edu.cn.

PMID: 30268411
DOI: 10.1016/j.jconhyd.2018.08.003

Abstract

Nitrogen (N) fertilizers have been extensively used to maintain soil fertility in intensively agricultural soils, creating serious environmental pollution. In this study, a 70-day incubation experiment was conducted to investigate the effects of different N fertilizers (urea, manure, straw) on N mineralization, soluble organic nitrogen (SON) dynamics and its leaching potential in typical agricultural soils of the Shandong Peninsula. The results showed that the addition of N fertilizers affected the SON pools and soil N mineralization in different ways owing to their various properties and interaction with soils. When comparing treatments, urea application was found to decrease SON content, whereas manure and straw addition increased the SON content after long-term incubation. Considering that SON content depended on a complicated formation process and consumption process, no direct link between SON content and N mineralization capacity was observed in different treatments. Additionally, we analyzed free amino acids (FAAs) in SON and found that FAA content was negatively correlated with N mineralization, except for the straw treatment. This suggested that FAAs were important substrates of N mineralization in soils. In addition, the composition of SON was determined by 3-dimensional excitation-emission matrix and ultraviolet-visible absorbance spectrophotometer after long-term incubation. The P_III+V/P_I+II+IV ratio, SUVA₂₅₄, and A₂₅₃/A₂₀₃ ratio decreased after fertilizer application. This indicated that fertilizer addition decreased the SON humification degree and increased SON leaching. Therefore, SON should be taken into account when optimizing fertilization management and evaluating the risk of N leaching in groundwater systems.

Keywords: Free amino acids; Groundwater system; Microbial biomass nitrogen; Nitrogen fertilizers; Soluble organic nitrogen; Soluble organic nitrogen leaching.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Agriculture / methods
Environmental Pollution
Fertilizers / analysis
Groundwater*
Manure
Nitrogen / analysis
Nitrogen Cycle
Organic Chemicals
Soil Microbiology
Soil* / chemistry
Water Pollutants* / analysis

Substances

Fertilizers
Manure
Organic Chemicals
Soil
Water Pollutants
Nitrogen