2016 INI | INI 2016

Dissimilatory nitrate reduction to ammonium, denitrification and anaerobic ammonium oxidation in paddy soil

2016 INI, Cropping systems and nitrogen efficiency, Impact Presentation

Arjun Pandey¹, Helen Suter¹, Jizheng He¹, Deli Chen¹

¹Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Burnley Campus, 500 Yarra Boulevard, Richmond, Victoria 3121, http://fvas.unimelb.edu.au/. Email: arjunp@student.unimelb.edu.au

Abstract

Nitrogen (N) is the most important yield-limiting nutrient for rice production. Flooding of rice paddies for an extended period of time creates anoxic conditions in soil which can favour a simultaneous occurrence of several microbial N transformation processes, such as dissimilatory nitrate (NO₃^–) reduction to ammonium (NH₄⁺) (DNRA), denitrification and anaerobic NH₄⁺ oxidation (anammox). Little is known about the role of DNRA and anammox in N cycling in paddy soils, and of the simultaneous occurrence of these N transformations. This study utilized a ¹⁵N isotopic approach to determine the rates of DNRA, denitrification and anammox processes simultaneously in a paddy soil. The paddy soil was collected from the Riverina region in New South Wales, Australia and studied under laboratory conditions. The rates of the processes were investigated after a week of flooding of paddy soil after a basal dose of N application at the rate of 1.6 g N m^-2 (farmers practice in the region). Results showed that DNRA contributed to the formation of 0.34 µmole NH₄⁺-N hr^-1 kg^-1 soil. Denitrification and anammox produced 3.35 µmole N₂ and 0.65 µmole N₂ hr^-1 kg^-1 soil, respectively. Denitrification was the major pathway contributing to N₂ production which accounted for 83% of total N₂ produced. Anammox contributed to 17% of total N₂ production. Considering the bulk density of soil (1.3 g cm^-3), it can be estimated that DNRA can retain 0.03 g N m^-2 day^-1, whereas denitrification and anammox can contribute to a loss of 0.58 and 0.11 g N m^-2day^-1, respectively, after the first week of flooding of paddy soil.

Regional assessment of dry and wet deposition of reactive nitrogen in East Asia

2016 INI, Impact Presentation, Reactive nitrogen deposition

Satomi Ban^1,2, Kazuhide Matsuda¹

¹Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan, satomi_ban@jesc.or.jp

²Japan Environmental Sanitation Center, 11 10-6 Yotsuyakami-cho, Kawasaki 210-0828, Japan

Abstract

In order to investigate the state of reactive nitrogen deposition in East Asia, we carried out a measurement-based assessment of nitrogen deposition on regional scale in cooperation with the Acid Deposition Monitoring Network in East Asia (EANET). We estimated the dry deposition amounts of HNO₃ and NH₃ in gas phase, and NO₃^– and NH₄⁺ in aerosol phase by a modified inferential method using monthly mean inputs of meteorological data. Dry deposition amounts estimated by the modified inferential method well reproduce those estimated by using high time resolution inputs in the case of long-term total dry deposition (e.g. annual deposition). The total (dry and wet) nitrogen depositions at 20 sites in 7 countries in East Asia were in the range of 2.8 – 37 kg N ha^-1 year^-1, and high total nitrogen deposition amounts over 10 kg N ha^-1 year^-1 were found in wide areas of the region. The highest amount in each site classification (urban, rural, and remote) was found at Chinese sites. The ratios of dry deposition to total deposition were high in the inland areas due to the low precipitation. And the ratios of reduced nitrogen to total nitrogen deposition were relatively high in southern part of East Asia.

Regional nitrate deposition inferred from ground- and space-based measurements

2016 INI, Impact Presentation, Reactive nitrogen deposition

Miaomiao CHENG¹, Zheng GUO², Fan MENG¹

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China, Email:chengmm@craes.org.cn

² Division of Remote Sensing Data Application, National Satellite Meteorological Centre, Beijing 100081, China

Abstract

Spatial and temporal nitrate deposition fluxes were assessed using satellite data in the Yangtze River Delta (YRD) from 1996 to 2011. Our study reveals significant spatial variations of nitrate deposition. In general, the fluxes of total (dry plus wet) nitrate deposition was up to 22 kg N ha^-1 yr^-1 with large loading rates received in winter. Most high fluxes appeared over urban (38 kg N ha^-1 yr^-1) and cropland (30 kg N ha^-1 yr^-1) areas. During the study period (1996-2011), a significant increasing trend of nitrate deposition was observed with an annual increasing rate of 1.33 kg N ha^-1 yr^-1. The spatial patterns of estimated nitrate deposition also showed that there were much higher fluxes and annual increasing trend in the middle region of YRD, i.e., the metropolitan areas contained Shanghai-Nanjing-Hangzhou cities, than in other areas. Our results also reveal that dry nitrate deposition contributed more than 50% of the total nitrate deposition over all provinces and land covers except coastal sea (14%), which indicates the relative importance of dry deposition to the total nitrate deposition in YRD region. Our study suggests that it is necessary to consider both dry and wet deposition when evaluating the influences of nitrate deposition on environment and ecosystem health.

Nitrogen inputs by rainfall, throughfall and stemflow in Brazilian semiarid

2016 INI, Feature Presentation, Reactive nitrogen deposition

R. L. Deusdará^{1 2}, M. C. Forti¹, L. S. Borma¹, R. S. C. Menezes³, J. R. S. Lima⁴, and J. P. H. B. Ometto¹, E. R. Sousa-Neto¹, K. Ribeiro¹

¹Centro de Ciência do Sistema Terrestre – CCST, sala 5, 3º andar, Instituto Nacional de Pesquisas Espaciais – INPE, Avenida dos Astronautas, 1758, 12227-010, São José dos Campos, SP, Brasil,

²karinne.deusdara@yahoo.com.br

³ Departamento de Energia Nuclear – DEN, Universidade Federal de Pernambuco – UFPE, Av. Prof. Luiz Freire, 1000, 50740-540, Recife-PE, Brasil

⁴ Universidade Federal Rural de Pernambuco – UFRPE, Avenida Bom Pastor, s/n, Garanhuns – PE, 55292-270, Brasil

Abstract

The aim of this study was to quantify nitrogen inputs by the rainfall, throughfall and stemflow, assessing the canopy role in the nitrogen transfers between atmosphere and soil in a rural tropical semiarid region in the Brazilian Caatinga. Samples were collected during two wet seasons, one during an extremely dry year (2012) and one during a year with normal rainfall (2013). The ionic concentrations of N-NH₄⁺, N-NO₃^–, dissolved organic nitrogen (DON) and dissolved total nitrogen (DTN) was 0.04 and 0.15, 0.07 and 0.10, 0.49 and 0.48, 0.61 and 0.73 mg l^-1 in the rainfall for 2012 and 2013, respectively. The canopy enrichment for DON were 3 times for both wet seasons and for DTN were 3 and 2 times in relation to rainfall values for 2012 and 2013, respectively. There were no differences in N-NO₃^– between rainfall and throughfall. The enrichment for stemflow were 31, 8, 15 and 17 times for N-NH₄⁺, N-NO₃^–, DON and DTN for the wet season for 2013, respectively. We report a low bulk nitrogen deposition during both wet seasons and an estimative of about 2.05 kg N ha^-1 ano^-1. We estimated slightly lower annual inputs than previous global estimates, likely due to the low rainfall depths that occurred during the studied years and the lack of measured data for South America. Our findings contribute to the knowledge of nitrogen deposition in the northeastern Brazil by providing information for this poorly studied tropical and semiarid ecosystem.

Atmospheric nitrogen deposition in a subtropical hydroelectric reservoir (Nam Theun II case study, Lao PDR)

2016 INI, Impact Presentation, Reactive nitrogen deposition

Adon¹, C. Galy-Lacaux², D. Serça², F. Guerin³, P. Guedant⁴, A. Vonghamsao⁴, W. Rode⁴.

¹Laboratoire de Physique de l’Atmosphère et de Mécanique des Fluides, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire, E-mail : adonatma@yahoo.fr

² Laboratoire d’Aérologie, Université de Toulouse, CNRS, UPS, France

³ GET (Geosciences Environnement Toulouse), UMR 5563, Toulouse, France

⁴Nam Theun 2 Power Company Limited (NTPC), Environment & Social Division – Water Quality and Biodiversity Dept. – Gnommalath Office, P.O. Box 5862, Vientiane, Lao PDR

Abstract

This study presents an estimation of the atmospheric inorganic nitrogen deposition into the NT2 hydroelectric reservoir, in the subtropical region of the Lao PDR, based on a two-year monitoring (June 2010 to July 2012) including gas concentrations and precipitation. Dry deposition fluxes are calculated from monthly mean surface measurements of NH₃, HNO₃ and NO₂ concentrations (passive samplers) together with simulated deposition velocities. Wet deposition fluxes are calculated from NH₄⁺ and NO₃^– concentrations determined in single event rain samples (automated rain sampler). Annual rainfall depth was 2502 mm and 3162 mm in 2010 and 2011, respectively. The average nitrogen deposition flux is estimated at 1.26 kg N ha^-1 yr^-1 from dry processes and 5.01 kg N ha^-1 yr^-1 from wet ones, i.e., an average annual total nitrogen flux of 6.3 kg N ha^-1 yr^-1 deposited into the NT2 reservoir with 80% from wet deposition.

Human nitrogen fixation and greenhouse gas emissions: a global assessment

2016 INI, Impact Presentation, Reactive nitrogen deposition

Wim de Vries^1,2, Enzai Du³, Klaus Butterbach-Bahl⁴, Lena Schulte-Uebbing², Frank Dentener⁵

¹Alterra Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, the Netherlands, wim.devries@wur.nl

² Environmental Systems Analysis Group, Wageningen University, PO Box 47, 6700 AA Wageningen, the Netherlands.

³ State Key Laboratory of Earth Surface Processes and Resource Ecology, and College of Resources Science & Technology, Beijing Normal University, Xinjiekouwai Street 19#, Beijing, 100875, China.

⁴Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany.

⁵ Joint Research Centre, Institute for Environment and Sustainability, Ispra, Italy.

Abstract

The net impact of human nitrogen (N) fixation on climate (ignoring short-lived components) mainly depends on the magnitude of the warming effect of (direct and indirect) nitrous oxide (N₂O) emissions and the cooling effect of N-induced carbon dioxide (CO₂) uptake. N-induced CO₂ uptake is caused by anthropogenic N deposition which increases net primary production (NPP) in N-limited ecosystems and thus CO₂ sequestration. Nitrogen oxide (NO_x) emissions, however, also induce tropospheric ozone (O₃) formation, and elevated O₃ concentrations reduce NPP and thus plant C sequestration. We estimated global-scale impacts of anthropogenic N fixation on net greenhouse gas emissions using recent data and modelling approaches with respect to N inputs to various ecosystems, N₂O emissions in response to N inputs, and C exchange in responses to N inputs (C–N response) and O₃ exposure (C–O₃ response). The estimated impact of human N fixation is dominated by an increase in N₂O emissions equal to 1.02 (0.89–1.15) Pg CO₂-C equivalent (eq) yr^-1. CO₂ uptake due to N inputs to terrestrial and aquatic ecosystems corresponds to net emissions of -0.75 (-0.97 to -0.56) Pg CO₂-C_eq yr^-1, while the reduction in CO₂ uptake by N-induced O₃exposure corresponds to net emissions of 0.14 (0.07–0.21) Pg CO₂-C_eq yr^-1. Overall, human N fixation causes an increase in net greenhouse gas emissions of 0.41 (-0.01–0.80) Pg CO₂-C_eq yr^-1. Even considering all uncertainties, it is likely that N inputs lead to a net increase in greenhouse gas emissions.

Evaluating the use of a web-based nitrogen cycle animation

2016 INI, Impact Presentation, National and community nitrogen footprints

Mark Imhof¹, Gemma Heemskerk² and Matthew Cox³

¹ Agriculture Victoria, Department of Economic Development, Jobs, Transport and Resources. 32 Lincoln Square Nth, Parkville, Victoria 3053. mark.imhof@ecodev.vic.gov.au

²Agriculture Victoria, Department of Economic Development, Jobs, Transport and Resources. 32 Lincoln Square Nth, Parkville, Victoria 3053. gemma.heemskerk@ecodev.vic.gov.au

³ Agriculture Victoria, Department of Economic Development, Jobs, Transport and Resources. 32 Lincoln Square Nth, Parkville, Victoria 3053. matthew.cox@ecodev.vic.gov.au

Abstract

An interactive animation of the nitrogen (N) cycle, within the context of a dairy agroecosystem, is available on the Victorian Resources Online website at: http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_nitrogen-cycle. It is one of a series of animations developed to capture and communicate soil knowledge and visually explain processes that occur in the soil and landscape. Animations were created from ‘storyboards’ (a series of hand-drawn sketches that outline all the events in the animation) developed with relevant soil scientists. This is an example of harnessing tacit knowledge of scientists, and providing context, to create an information product aimed at a broad range of users. Feedback to date has highlighted the value to users involved in agricultural extension and education. User profiling (based on IP address tracking) for a three-month period in 2013 indicated that the N cycle animation was the most extensively accessed of all animations on the website. The education and government sectors were significant user groups.

Do environmental scientists behave more environmentally friendly with regard to nitrogen pollution?

2016 INI, Impact Presentation, National and community nitrogen footprints

Adrian Leip¹, Claudia Marques dos Santos Cordovil², Patrick Musinguzi³, Ina Körner⁴

¹European Commission, Joint Research Centre, Institute for Environment and Sustainability, Via Fermi 2749, TP 266/040

I-21027 ISPRA (VA), Italy, https://ec.europa.eu/jrc/en, adrian.leip@jrc.ec.europa.eu

² Universidade de Lisboa, Instituto Superior de Agronomia, LEAF, Tapada da Ajuda, 1349-017 Lisboa, Portugal

³ Department of Agricultural Production, School of Agricultural Sciences, Makerere University, Kampala, Uganda

⁴ Hamburg University of Technology, Institute of Wastewater Management and Water Protection; Bioconversion and Emission Control Group, 21073 Hamburg, Germany

Abstract

Nitrogen neutrality is a novel concept that aims at reducing the N-footprint caused by an entity and offsetting the residual emission of reactive nitrogen (Nr). This concept had been applied to three conferences (6th International Nitrogen Conference in 2013 in Kampala, Uganda; 18th Nitrogen Workshop in 2014 in Lisbon, Portugal; 15th Ramiran Conference in Hamburg, Germany) with different concepts and different degree of willingness of the participants to contribute to the voluntary compensation fee. This paper analyses the results of surveys made among the participants of the conferences to understand their view on low-impact conferences, N-footprints, and the N-neutrality concept.

The effect of ecosystem engineers on N cycling in an arid agroecosystem

2016 INI, Impact Presentation, National and community nitrogen footprints

Jessica G. Ernakovich¹, Theodore A. Evans², Ben Macdonald³, Mark Farrell⁴

¹CSIRO Agriculture & Food, PMB 2, Urrbrae, SA, 5064, http://people.csiro.au/E/J/Jessica-Ernakovich, jessica.ernakovich@csiro.au

² School of Animal Biology, University of Western Australia, Perth, WA 6009, theo.evans@uwa.edu.au

³ CSIRO Agriculture & Food, Canberra, ACT, 2601, ben.macdonald@csiro.au

⁴CSIRO Agriculture & Food, PMB 2, Urrbrae, SA, 5064, http://people.csiro.au/F/M/Mark-Farrell.aspx, mark.farrell@csiro.au

Abstract

Ecosystem engineers—such as earthworms, termites and ants—are an important component of soil biodiversity and have been shown to contribute to aboveground productivity in native and managed ecosystems. Although their role in physical alteration of soils is appreciated, less is known about their effect on soil nutrient cycling, particularly in arid systems where termites and ants are the dominant ecosystem engineers. We explored the effect of termite reduction and tillage on soil nitrogen (N) biogeochemistry in soils from the northeasternmost wheat growing region in Western Australia. We assessed total soil N, potentially mineralizable N, and dissolved N pools, as well as soil N fluxes, such as proteolysis and N mineralization. We predicted that soils with native termite and ant populations would have greater N pools and rates of transformations between pools. While we found that many soil N pools were up to 2.5 times larger with native termite populations (e.g. dissolved organic N, NH₄⁺), we found that the rate of transformations between pools was reduced relative to the reduced termite plots. While the reason behind this trend needs further exploration, the larger soil N pools in sites with native levels of ecosystem engineers implies that the conservation of soil macrofauna, particularly those that translocate N through the soil profile, may be important in the sustainable management of cropped lands.

Colorado State University Nitrogen Footprint Project

2016 INI, Impact Presentation, National and community nitrogen footprints

Jacob Kimiecik¹, Jill Baron²

¹Colorado State University, Fort Collins, CO, 80523-1499 Jacob.Kimiecik@gmail.com

²USGS, Colorado State University, Fort Collins, CO, 80523-1499 Jill.Baron@colostate.edu

Abstract

Universities are a significant source of nitrogen that is released to the environment leading to environmental harm. Colorado State University (CSU) is a large land grant institution working toward sustainability goals, and in 2014 added a goal of reducing its nitrogen (N) footprint. The CSU released N to the environment during the period August 2014-August 2015 from utilities, transportation, housing and dining, research animals, and research farms. The N footprint came to 1,066 metric tons N, of which only 28% was caused by on-campus activities. Most of CSU’s N footprint comes from Agricultural Experiment Stations and other research facilities around Colorado. Because of agricultural activity, CSU has a higher N-footprint by an order of magnitude than other universities that are part of the Nitrogen Footprint Network. On the university campus food production, utilities, and research animals are the largest sources of released N, and we describe an active program of education, incentives, and linking N reductions to greenhouse gas reductions.

Key Words

university, abatement, nitrogen footprint network, agricultural research