Estimation of N2 and N2O production in a eutrophic river using a newly developed gas trap device

Yan Gao a, 1, Zhenhua Zhang a, Xinhong Liu a, Neng Yi a, Li Zhang a, Yan Wang a, Shaohua Yana

aInstitute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, 50 Zhongling Street, Nanjing 210014, China;


Biogenic gas production in a eutrophic pond located in the subtropical climate zone of China was quantified using a newly developed gas-trapping device. This device allows for a vertically resolved collection and subsequent analysis of biogenic gases (N2, O2, N2O and CH4). Determining the vertical structure of gas production is especially relevant in stratified water bodies as it allows to link the stratification of physicochemical parameters with the gases produced. The investigated pond exhibited strong thermal stratification in temperature, DO, pH, nutrients and Chlo-α during summer and autumn, but not in winter. Gas production was greatest at the sediment-water interface and in the surface layer and small in the middle layer. Gases produced at the surface were mainly N2 and O2, whereas the latter is likely to stem from photosynthetic activity as gas production followed a diurnal cycle. At the sediment-water interface, the collected gas was mainly composed of N2 and CH4. Our results highlight the vertical heterogeneity of gas production and underline the value of vertically-resolved sampling which is made possible with the presented gas-trapping device.

Assessment of nitrogen mineralization of organic materials on sands of Central Vietnam: incubation experiments

Hoang Thi Thai Hoa1, Tran Thi Anh Tuyet1, Do Dinh Thuc1, Surender Mann2, Richard Bell2

1 Hue University- Hue College of Agriculture and Forestry, 102 Phung Hung street, Hue city, Thua Thien Hue province, Vietnam, 530000,,

2 School of Veterinary and Life Sciences, Murdoch University, Murdoch WA 6150 Australia


Sandy soils of Central Vietnam represent an important soil order that increasingly contributes to regional economic growth. However these soils have generally low productivity because of chemical and physical constraints associated with low pH values and sand contents exceeding 70%, are common for those soils. Obviously, organic matter management represents a key factor for crop productivity improvement on these soils. However, before considering the possible contributions of various organic amendments, it is important to evaluate the actual contribution of the initial soil organic matter through its N-mineralization, considered as a prime source of N for plants. Therefore, soil samples (0-20 cm) representing peanut growing sandy soils were collected before the spring season to incubate with 4 types of organic materials which added to the same sandy soil amount under anaerobic conditions for 0, 5, 10, 20, 30 and 40 days to determine their N-mineralization capacity. The release of NH4+, NO3 was on average higher in treatments with added organic fertilizers. Significant amounts of NH4+ and NO3 were found with different types of organic materials added to the soil and increased with the time of incubation from 5 to 40 days after incubation. Fitting the results with a first order kinetic equation led to the calculation of potentially mineralizable nitrogen. The N-pool identified in this study can be considered as very labile N which might be available to crops within few weeks. Therefore, the total N-content of soils cannot be considered as a reliable indicator of short term N-availability.

Accumulated nitrogen from organic fertilizer affects river nitrogen pollution

Kuroda Hisao1, Lin Xiaolan2, Kitamura Tatsumi3, Oouchi Takao3 and Sugaya Kazuhisa3

1 College of Agriculture, Ibaraki University, 3-21-1, Chuuo, Ami-town, Inashiki, Ibaraki, 300-0393, Japan,,

2 United Graduate School of Agricultural Science Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-city, Tokyo 183-8509, Japan

3 Ibaraki Kasumigaura Environmental Science Center, 1853 Okijyuku Tsuchiura-city Ibaraki 300-0023, Japan.


Lake Kasumigaura is the second largest lake in Japan and it is eutrophic. Nutrient loads from agriculture and livestock waste have been identified as a possible cause. Of particular concern are increasing nitrogen concentrations in the Hokota River, where pig farming is a major enterprise. The Japanese government has been advocating conservation measures such as a reduction in the use of chemical fertilizers and synthetic pesticides. As a result, organic forms of nutrients were believed to be good for the environment and less harmful than chemical fertilizers.  However, incorrect application of nutrients in any form may contribute to nitrogen pollution. We propose that increasing nitrogen concentrations in Hokota River results from excessive application of swine manure to upland fields, as there has not been an increase in the amount of mineral fertiliser applied. Similarly, increases in nitrogen concentration were observed in spring water (from ground water to surface water) below an upland field that received a large application of horse manure.

In addition, soil core results from an upland field receiving nitrogen inputs for 30 years and subsequently drained in 2011 showed slow movement of residual soil nitrogen from the profile.  As a result, residues of nitrogen remain in the soil from historical nitrogen inputs. Nitrogen leaching from the upper portion from rainfall during the last few years was evident, but slow. These results suggest that there was long-term nitrogen leaching potential due to the influence of the accumulated nitrogen. As a result, it was concluded: 1)  Livestock waste or organic fertilizer is a likely significant contributor to nitrogen pollution. 2) Nitrogen water quality signatures lag behind the application of organic nitrogen (manure). 3) the infiltration of nitrogen from the soil in upland fields is driven by rainfall.

Monitoring nitrogen processing in constructed wetlands: two stable isotope approaches

Keryn Roberts1, Md Moklesur Rahman2, Wei Wen Wong2, Perran Cook2, Michael Grace2

1 Water Studies Centre, Monash University, Wellington, Clayton, Victoria, 3800, Australia,

2 Water Studies Centre, Monash University, Wellington, Clayton, Victoria, 3800, Australia


The increased pressure of anthropogenic nitrogen inputs on our waterways has increased the importance of nitrogen management strategies such as constructed wetlands. Several studies have assessed the effectiveness of wetland operation by examining wetland components in the design process, however, long term management of operational wetlands is often reliant on monitoring only nutrient concentrations. Stable isotopes of nitrogen can be a useful tool in investigating nitrogen processing and are often applied to detailed mechanistic studies but rarely utilised in ongoing monitoring strategies. Here we present a conceptual model for two stable isotope approaches, one quantitative and one qualitative, to assess their feasibility as management tools to improve our current understanding of nitrogen removal over the lifetime of a constructed wetland system. The first approach is the direct measurement of NO3 reduction pathways (denitrification) to assess nitrogen removal whilst the second approach uses the dual isotopic composition (δ15N and δ18O) of NO3 at the natural abundance level in the surface water to qualitatively assess denitrification and assimilation. We propose the natural abundance stable isotope approach, with further research, would complement current monitoring programs providing further information on the behaviour of nitrogen in wetlands.

Effect of amending nitrogen on the total carbon of arable soil in semi-arid region

Wenxu Dong1, Yuying Wang1, Xiaoxin Li1, Chunsheng Hu1

1 Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.  E-mail:


Soil inorganic carbon (SIC) exerts a strong influence on the carbon (C) sequestered in response to nitrogen (N) additions in arid and semi-arid ecosystems, but limited information is available on in situ SIC storage at the field level. This study determined the soil organic/inorganic carbon storage in the soil profile at 0–100 cm depths in 4 N application treatments (0, 200, 400, and 600 kg N ha-1 y-1) for 15 years in the North China Plain. Results showed that after 15 years of N fertilizer application the SOC contents at depths of 0-100 cm significantly increased, whereas the SIC contents significantly decreased at depths of 0-60 cm. However, the actual measured loss of carbonate was far higher than the theoretical maximum values of dissolution via protons from nitrification. Furthermore, the amount of HCO3 and the HCO3/ (Ca2+ + Mg2+) ratio in soil leachate were higher in the N application treatments than no fertilizer input (CK) for the 0-80 cm depth. The result suggested that the dissolution of carbonate was mainly enhanced by soil carbonic acid, a process which can absorb soil or atmosphere CO2 and less influenced by protons through the nitrification which would release CO2.

NOx emissions reduction programs have translated to improved ozone air quality and forest health in the Eastern United States

Jason Lynch, Clara Funk and Richard Haeuber

U.S. Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC, 20006,,


Data from several monitoring programs are examined to assess the effectiveness and environmental benefit of air pollution reduction programs in the United States (U.S.).  Integrated assessment of monitoring data demonstrates that reductions of nitrogen compound emissions, such as NOx, and byproducts like ozone lead to improved air quality and forest ecosystem health.  Three important environmental monitoring programs were used to evaluate the impact of emission reductions and improved ozone concentrations on forest health.  Assessing the impact of ground-level ozone on forests in the eastern U.S. involves understanding the risk to tree species from ambient ozone concentrations and accounting for the prevalence of those species within the forest. As a way to quantify the risk to particular trees, scientists have developed concentration-response (C-R) functions that relate ozone exposure to tree response.  In 2014, regulated pollution sources reduced NOx emissions by 4.7 million tons (73%) from 1990 levels.  Based on regional data from CASTNET from 2000 through 2014, annual mean ambient nitrate concentration (an ambient pollutant resulting from NOX emissions) declined 48% from 3.1 ppb to 1.6 ppb in the eastern U.S. Rural ozone concentrations, calculated as DM8A, were found to decrease from 84 ppb to 66 ppb (22%) from 2000-2002 and 2012-14 in the eastern U.S.  Comparing data from the start of the NOX Budget Trading Program (2000-2002) to 2007-2009, we found that the total land area in the Eastern U.S. with significant biomass loss decreased substantially for all sensitive tree species as NOx emissions and concentrations of ambient nitrogen compounds have declined over this time period.

Catchment topography and the distribution of electron donors for denitrification control the concentration of nitrate in headwater streams of the Lake Hachiro watershed

Atsushi Hayakawa, Yu Funaki, Tatsuya Sudo, Ryoki Asano, Shintaro Watanabe, Yuichi Ishikawa, Shin Hidaka

Department of Biological Environment, Faculty of Bioresource Science, Akita Prefectural University, Akita, 010-0195, Japan,


We examined the linkages between topography and electron donors for denitrification in headwater streams in the Lake Hachiro watershed that has marine sedimentary rocks. In 33 headwater streams, we sampled water at the catchment nine times in 2 years. Stream sediment was sampled once for measurement of denitrification potential (DP), water-extractable soil organic carbon (WESOC), and easily oxidizable sulfide (EOS), which are considered the principal potential electron donors for denitrification. The topographical features of each catchment were calculated using a digital elevation model with 10-m grid cells. Stream NO3 concentrations displayed large spatial variation among catchments, ranging from 0.06 to 0.52 mg N L–1, and were significantly positively correlated with slope in the catchments (r = 0.663, P < 0.01, n = 33), indicating that NO3 was removed to a greater extent in gentle slope catchments. Generalized linear model showed slope, slope aspect, sediment DP, and EOS significantly affected in-stream NO3 concentration. Stream SO42– concentrations tended to increase as NO3 concentrations decreased and EOS contents increased, indirectly indicating sulfur-mediated denitrification. NO3 reduction with SO42– production, and sulfur-oxidizing bacteria was detected in the stream bank soil with high EOS content. We conclude that catchment topography and the distribution of electron donors in riverbed sediment explain the spatial variation in in-stream NO3 concentration and, by inference, catchment denitrification. These results indicate that more NO3 may be denitrified by sulfur-mediated denitrification owing to the abundance of sulfides in the catchment from marine sedimentary rocks.

Genotypic variability in wheat for preference of NH4+, NO3- or NH4+NO3

Cathryn O’Sullivan1, Jairo Palta 1, Mark Farrell2, Karen Treble1.

1 CSIRO Agriculture, 147 Underwood Ave, Floreat, WA, 6014,,

2 CSIRO Agriculture, Waite Road, Urrbrae SA 5064,,


Improving the nitrogen (N) uptake efficiency (NUpE) of wheat has the potential to offer significant economic gains to growers and improvement in environmental quality. One way to improve NUpE may be by matching wheat genotypes which have greater uptake efficiency for NH4+ or NO3 to soil types that favour the production of one of these N forms over the other. Surprisingly there has been little previous research investigating the genotypic variation in wheat for preference of different forms of N. The aim of this study was to screen a range of wheat cultivars and landraces for their ability to uptake N and produce biomass on NH4+, NO3 and a mixture of NH4NO3. To date, 21 wheat genotypes have been grown hydroponically on three different nutrient solutions providing N as NH4+, NO3 or NH4NO3. The nutrient solutions were all supplemented with a nitrification inhibitor, well aerated and pH controlled. At 8 weeks after sowing (post-tillering for all lines) the shoots were harvested and leaf area, shoot biomass and N content measured.

There is significant variation among the genotypes tested in their ability to uptake N and produce biomass on different N sources. Several cultivars, including Frame and Gamenya, produced more biomass with higher N content on NO3-. Others, including Yitpi and Wyalkatchem performed best on NH4+ while others, including Halberd and Condor, performed better on NH4NO3 than on either NO3 or NH4+. This information is critical for further research to determine whether it is possible to improve NUpE by targeting genotypes with differing N preferences to soil types where a particular N form is likely to occur.

Effects of nitrogen fertilization on potato yields and soil nitrate leaching

Zisheng Xing1,2, Bernie. J. Zebarth1, Sheng Li1,2*, Fanrui Meng2, Herb. W. Rees1, Noura Ziadi3, and Lien Chow1

1 Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, PO Box 20280, 850 Lincoln Road, Fredericton, New Brunswick, Canada E3B 4Z7,*Corresponding Author:

2 Faculty of Forestry & Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada E3B

3 Quebec Research and Development Centre, Agriculture and Agri-Food Canada,  2560 Blvd. Hochelaga, Québec QC G1V 2J3, Canada, presenter: / Tel: 418-210-5052 / TTY:  613-773-2600


A 2-year field trial with a randomized complete block design with four replications was conducted in New Brunswick, Canada to evaluate N fertilization effects on potato (Solanum tuberosum L.) tuber yields and quality as well as soil nitrate leaching. Eight N fertilizer treatments were examined, including three N sources (i.e. conventional, controlled-release and organic fertilizers) at two application rates (100 and 200 kg N ha-1),  a split application of conventional fertilizer at the high rate and a zero N fertilizer input as control. Application of N-fertilizer significantly increased tuber yield (by 76% maximum) and quality over the unfertilized treatments whereas differences between the two N fertilizer application rates were non-significant. Fertilizer use efficiency varied from 16% to 56% over treatments and years. Low application rates resulted in lower seasonal soil and soil solution NO3 concentrations than high application rates. The controlled-release and organic form of fertilizer both reduced seasonal mean soil and soil solution N concentrations than conventional fertilizer, with low leaching potential.