Archive for the category: Reactive nitrogen processes

Liuqing Yang^{1, 2}, Xiaotang Ju¹*,Xiaojun Zhang²*

¹ China Agricultural University, No.2 Yuanmingyuan Xilu, Haidian District, Beijing, China, 100193, yangliuqing.1224@163.com
²Shanghai Jiao Tong University, No.800 Dongchuan Road, Minhang District, Shanghai, China, 200240
*Author for correspondence juxt@cau.edu.cn;  xjzhang68@sjtu.edu.cn

Abstract

The linkage between situ N₂O emissions and abundance of functional genes ammonia monooxygenase  gene (amoA), nitrate reductase gene (narG), nitrite reductase genes (nirS and nirK), N₂O reductase gene (nosZ) is not well understood, impeding proposing methods for mitigation in agricultural management. Our work was focusing on this linkage. Combined traditional study method and molecular biological technique and four treatments were involved in: N₀ (Zero N application, straw removal), N_opt and CN_opt (Improved N_min test, straw removal and return respectively), CM (Manure supplementary, chemical fertilizer N based on N balance calculation, straw return). Soil samples were collected on 16^th April (reflect long-term N and C management effect), 9^th and 14^th August (reflect before and after short-term fertilization on 11^st August) for biological and chemical properties analysis. We found that the amoA gene responed to short-term fertilizer while denitrification genes had no response and annual N₂O emission had significant positive relationships with gene abundance mentioned above. We concluded that strong nitrification triggered by high ammonia concentration after fertilization, nitrifier denitrification or denitrification triggered by strong rainfall or irrigation in normal crop growing days without nitrogen addition were most probably responsible for N₂O emissions. It is critical to reduce amoA gene function after urea-based fertilization. Meanwhile, we need to pay attention to enhanced denitrification genes functions in their favourable conditions to produce N₂O when increased SOC due to long-term manure fertilization.

LIN Xiaolan¹, YOSHIDA Koshi², MAEDA Shigeya², KURODA Hisao²

¹ The United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo, Japan, 183-8509, linxiaolan0402@gmail.com

² College of Agriculture, Ibaraki University, 3-21-1, Chuuo, Ami, Inashiki, Ibaraki, Japan, 300-0393

Abstract 

The characteristics of oxidation-reduction (redox) layers were reviewed under natural conditions. This study was carried out a field survey from 2014 to 2015. The survey was conducted in a paddy field. Soil temperatures, air temperatures, and T-N concentrations of water had been measured. The dissolved oxygen (DO) concentrations of redox layers in flooded soil were measured per 0.2 mm with a special DO concentration sensor through surface to 6 cm depths of soils. Based on the DO concentration results, the soil of the oxidized layers where the concentration was over 1 mg L^-1 was sampled, along with reduced layer of less than 0 mg L^-1. The denitrification activities of redox layers were measured by acetylene blocking technique.

The DO concentrations in paddy field soil have a seasonal change and changed in a thin layer. A positive correlation is observed between the thickness of the oxidized layer and soil surface temperature in the range of 12 ~ 24 °C. The oxidized layer denitrification activities are little, denitrification of paddy fields is dependent on the reduced layer.

Peter R. Quin^{1, 2, 3}, Lukas van Zwieten^{1, 2, 3}, Peter R. Grace⁴, Lynne M. Macdonald⁵, Annette L. Cowie^{1, 6}, Dirk V. Erler⁷, Iain M. Young⁸, Stephen W. Kimber²
1 – School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia. Email: peter.quin@internode.on.net

2 – NSW Department of Primary Industries, 1243 Bruxner Highway, Wollongbar, NSW 2477, Australia.

3 – Southern Cross Plant Science, Southern Cross University, Military Rd, East Lismore, NSW 2480, Australia.

4 – Institute for Sustainable Resources, Queensland University of Technology, 2 George St, Brisbane, QLD 4000, Australia.

5 – CSIRO Agriculture, Glen Osmond, SA 5064, Australia.

6 – NSW Department of Primary Industries, Trevenna Rd, University of New England, Armidale, NSW 2351, Australia.

7 – School of Environment, Science and Engineering, Southern Cross University, Military Rd, East Lismore, NSW 2480, Australia.

8 – School of Life and Environmental Sciences, Faculty of Science, University of Sydney, NSW 2006, Australia.

Abstract

Increasing concentrations of atmospheric nitrous oxide (N2O) are making a significant contribution to anthropogenic climate change and the depletion of stratospheric ozone. These increases are known to primarily result from the use of synthetic nitrogen fertilisers and manures. Our study aimed to answer some of the many remaining questions about the mechanisms of production and movement of N2O in soil. In a field study we injected ¹⁵N-labelled nitrate into repacked columns of Ferralsol, at a depth of either 75 mm or 200 mm. We sampled soil gas at 3 depths and surface emissions. In-soil concentrations of N2O rose by approximately two orders of magnitude when water-filled pore space increased to >80 %. This coincided with periods of high hydraulic conductivity, potentially draining dissolved ¹⁵N2O from the 75 mm injected columns at 189 µg ¹⁵N-N2O m^-2 h^-1 compared with a surface flux of 1.2 µg ¹⁵N-N2O m^-2 h^-1 and from 200 mm injected columns at 30 µg ¹⁵N-N2O m^-2 h^-1 compared with a surface flux of 0.24 µg ¹⁵N-N2O m^-2 h^-1. Data suggests that indirect emissions of N2O by leaching and surface runoff from some soils may be much greater than the default 0.225 % of N applied recognised by the IPCC. This may go some way towards reconciling the discrepancy between ‘top down’(~4 %) and ‘bottom up’ (~1.3 %, IPCC default) estimates of direct N2O emissions from applied N. We also show that deeper placement of nitrate fertiliser may decrease direct N2O surface emissions, although the effect on indirect emissions remains unclear.

Hoang Thi Thai Hoa¹, Do Dinh Thuc¹, Trinh Thi Sen¹, Tran Thi Xuan Phuong¹

¹ Hue University – Hue College of Agriculture and Forestry, 102 Phung Hung street, Hue city, Thua Thien Hue province, Vietnam, 530000, http://www.huaf.edu.vn, hoangthithaihoa@huaf.edu.vn

Abstract

Wetland rice is the largest source of CH₄ emission from cropping and also offers the most options to modify crop management for reducing these emissions. The experiment was conducted in two rice cropping systems in 2014 and 2015 to assess the influence of rates and types of nitrogen fertilizer on CH₄ emission in rice fields of Central Vietnam. Results show that high fertilizer N rates (120 kg N ha⁻¹) increased seasonal cumulative CH₄ emissions from 11.6 – 26.7 g m^-2 for urea and 6.7 – 19.5 g m^-2 for ammonium chloride in winter spring and summer cropping seasons relative to when no N fertilizer was applied. Replacing urea with ammonium chloride at the same N rate significantly reduced CH₄ emissions by 35% (winter spring cropping season) and 32% (summer cropping season) at the rate of 120 kg N ha^-1_. Average CH₄ emission was about 2.1 – 2.2 times higher in summer season as compared in winter spring season. To develop effective GHG mitigation strategies future work is needed to (i) quantify the effects on both CH₄ and N₂O emissions), (ii) investigate options for combining mitigation practices.

Baobao Pan¹, Shu Kee Lam¹, Arvin Mosier¹, Yiqi Luo², Deli Chen¹

1 Crop and Soil Science Section, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, VIC 3010, Australia, Email: bpan@student.unimelb.edu.au

2 Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA

Ammonia (NH₃) volatilization is a significant pathway of nitrogen (N) loss from cropping systems. A number of studies have investigated the effects of management practices on NH₃ emission, but the findings are sometimes contradictory or inconclusive. A meta-analysis was conducted to quantitatively synthesise the global literature on the strategies for mitigating NH₃ emission from agricultural systems. Unlike qualitative reviews, a meta-analysis combines results from different studies to identify patterns among study results. The mitigation strategies included in our meta-analysis were: irrigation, N application method (deep placement), fertilizer type (ammonium-based vs. urea) and the use of urease inhibitors and controlled release fertilizers. Irrigation after fertilization and deep placement of N fertilizers decreased NH₃ emission by around 35% and 55%, respectively. Ammonium-based fertilizers decreased NH₃ loss by 31-75% when compared to urea. Both urease inhibitors and controlled release fertilisers effectively decreased NH₃ volatilization by 54-68%. The findings provide critical information on how to minimize NH₃ volatilization and increase N use efficiency and productivity in cropping systems.

Mei Bai^1*, Helen Suter¹, Shu Kee Lam¹, Rohan Davies², Deli Chen¹

¹ Crop and Soil Sciences Section, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia

²BASF Australia Ltd., Southbank, VIC 3006, Australia

*Corresponding author: mei.bai@unimelb.edu.au

Abstract

Ammonia (NH₃) volatilization to the atmosphere following urea based nitrogen (N) fertilizer application not only causes nutrient loss but also detrimentally impacts on the environment, our ecosystems, and contributes to global warming (as an indirect greenhouse gas). Here, we report our studies of quantifying NH₃ emissions from dairy pasture following urea application, and the effectiveness of a urease inhibitor in mitigating NH₃ loss. Two experiments were conducted in summer at Queensland (northern site) and autumn at South Australia (southern site) where urea was surface applied to pasture. A urease inhibitor (NBPT, applied with urea as Green ureaNV^TM) was added at the northern site. Open-path NH₃ laser concentration sensors were used to measure line-averaged concentrations along an open path downwind of the treatment plots. Ammonia fluxes were calculated using the inverse-dispersion technique (WindTrax). We found NH₃ flux increased following urea application and varied temporally at the two sites. Daily average NH₃ flux from dairy pastures fertilized with urea was 4.4 ± 0.46 and 6.4 ± 1.2 mg N m^-2 h^-1 for the northern and southern sites, respectively. Nitrogen loss as volatilised NH₃ from the urea application over the course of the experiments (12-15 days) accounted for approximately 40 and 60% of total applied N for the northern and southern sites, respectively. The difference between sites is likely attributed to the differences in N input, soil properties and microbial activity. The urease inhibitor reduced NH₃ emissions by approximately 71% compared to that from the urea treatment. The results in these studies also demonstrated that inverse-dispersion technique combined with the open-path lasers is able to measure NH₃ fluxes from large-scale field sites, and the open-path NH₃ laser has adequate detection resolution.

Adrian Leip, Gema Carmona-Garcia, Simone Rossi

¹ European 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

Abstract

We assessed the question of side effects and of the accountability of mitigation measures in the Agriculture, Forestry, and Other Land Uses (AFOLU) sector in national greenhouse gas inventories, proposing a novel classification system of available mitigation measures on the basis of ‘mitigation strategies’ and ‘mitigation mechanisms’. While the first differentiates measures which require collection of data from those for which specific emission factors or parameters need to be developed, the second groups mitigation measures according to the ‘term’ that is exploited to achieve emission reductions. We find that current IPCC methodologies provide a good basis to account for the majority of mitigation measures. Most of them will be reflected in national greenhouse gas inventories if default tier 1 approaches or (in some cases) national level tier 2 approaches are used (according to IPCC terminology). Efforts should be concentrated on improving data availability especially about management options, which is often the major obstacle in accounting for the effect of mitigation efforts. Examples include mitigation measures focusing on the improvement of feed intake of animals, or actions aimed at incrementing the soil organic carbon stock in agricultural soils through appropriate management practices. We conclude that simple farm level tools may have a good potential in collecting the data required, and offer the opportunity of full flexibility for the farmers to select concrete farm practice changes and monitor their performance.

Enrico Dammers¹, M. Palm², Martin Van Damme³, Mark W. Shephard⁴, Lieven Clarisse³, Karen E. Cady-Pereira⁵, Simon Whitburn³, Pierre Francois Coheur³, M.Schaap⁶ and Jan Willem Erisman^1,7

¹ Cluster Earth and Climate, Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands. E.Dammers@vu.nl

2 Institut für Umweltphysik, University of Bremen, Bremen, Germany

3 Spectroscopie de l’Atmosphère, Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), Brussels, Belgium

4 Environment Canada, Toronto, Ontario, Canada

5 Atmospheric and Environmental Research (AER), Lexington, Massachusetts, USA

6 TNO, Climate Air Sustainability, Utrecht, the Netherlands

7 Louis Bolk Institute, Driebergen, the Netherlands

Abstract

Global emissions of reactive nitrogen have increased due to human activities and are estimated to be a factor four larger than pre-industrial levels. Concentration levels of NO_x are declining, but ammonia (NH₃) levels are increasing globally. At its current concentrations NH₃ poses a large threat to both the environment and human health. Still relatively little is known about the total budget as well as the global distribution. Surface observations are sparsely available, mostly for north-western Europe, the United States and China, and are limited by the high costs and poor spatial and temporal resolution. The lifetime of atmospheric NH₃ is short, in the range of several hours to a few days and the existing surface measurements are not sufficient to estimate global concentrations. Space-based InfraRed-sounders such as the Infrared Atmospheric Sounding Interferometer (IASI) and the Cross-track Infrared Sounder (CrIS) enable global observations of atmospheric NH₃ which can overcome the limitations of existing surface observations. One challenge with satellite NH₃ retrievals is that they are complex and require extensive validation. Presently only a limited number of satellite NH₃ validation campaigns have been performed with limited spatial, vertical and temporal coverage. In this study we demonstrate the use of a recently developed retrieval methodology for ground-based Fourier Transform Infrared Spectroscopy (FTIR) instruments to obtain vertical concentration profiles of NH₃. We will use the retrieved profiles from eight stations with a range of NH₃ pollution levels to validate satellite NH₃ products.

Andrea Móring^1,2, Massimo Vieno², Ruth M. Doherty³, Celia Milford^4,5, Eiko Nemitz², Marsailidh M. Twigg², Mark A. Sutton²

¹ University of Edinburgh, High School Yards, Edinburgh, United Kingdom, EH8 9XP, andrea.moring@ed.ac.uk
² Centre for Ecology & Hydrology, Bush Estate, Penicuik, United Kingdom, EH26 0QB
³ University of Edinburgh, The King’s Buildings, Alexander Crum Brown Road, Edinburgh, United Kingdom, EH9 3FF
⁴ Associate Unit CSIC University of Huelva ”Atmospheric Pollution”, CIQSO, University of Huelva, Huelva, Spain, E21071
⁵ Izaña Atmospheric Research Center, AEMET, Joint Research Unit to CSIC “Studies on Atmospheric Pollution”, Santa Cruz de Tenerife, Spain

Abstract

In this study a process-based ammonia (NH₃) exchange model for a grazed field has been described and evaluated. The presented model is based on a patch-scale NH₃ exchange model, GAG (Generation of Ammonia from Grazing), which has been here extended to the field scale. GAG accounts for the total ammoniacal nitrogen and water content of the soil as well as the soil pH under a single urine patch. The new, field scale model combined multiple runs of the patch-scale model including both urine-affected and unaffected areas. The field-scale model was tested over two modelling periods, using NH₃ flux measurements taken at an intensively managed grassland, Easter Bush, UK. The model represented well the observed fluxes. It was found that the temporal evolution of the NH₃ exchange flux was dominated by the NH₃ emission from the urine patches. The results also showed that the evolution of NH₃ emission from urine patches deposited in different time steps could be substantially different: in some cases the first high NH₃ emission peak occurred a day or two days after the deposition of the given urine patch. Furthermore, according to our findings, NH₃ fluxes over the field in a given day could be considerably affected by the NH₃ emission from urine patches deposited several days earlier. The approach is designed to provide a balance between simplicity and process representation to allow it to be ultimately applied in regional scale atmospheric emission, transport and deposition modelling.

David R. Kanter^1,2, Sonali P. McDermid^1,3, Larissa Nazarenko³

¹Department of Environmental Studies, New York University, 285 Mercer Street, New York, NY, 10003, USA

²Agriculture and Food Security Center, Columbia University, 61 Route 9w, Palisades, NY, 10964, USA

³NASA Goddard Institute for Space Sciences, 2880 Broadway, New York, NY, 10025, USA

Abstract

Nitrous oxide (N₂O) is an important greenhouse gas and ozone depleting substance as well as a key component of the nitrogen cascade. While emissions scenarios indicating the range of N₂O’s potential future contributions to radiative forcing are widely available, the impact of these emissions scenarios on future stratospheric ozone depletion is less clear. This is because N₂O’s ozone destructiveness is partially dependent on tropospheric warming, which affects ozone depletion rates in the stratosphere. Consequently, in order to understand the possible range of stratospheric ozone depletion that N₂O could cause over the 21^st century, it is important to decouple the greenhouse gas emissions scenarios and compare different emissions trajectories for individual substances (e.g. business-as-usual carbon dioxide (CO₂) emissions versus low emissions of N₂O). This study is the first to follow such an approach, running a series of experiments using the NASA Goddard Institute for Space Sciences ModelE2 atmospheric sub-model. We anticipate our results to show that stratospheric ozone depletion will be highest in a scenario where CO₂ emissions reductions are prioritized over N₂O reductions, as this would constrain ozone recovery while doing little to limit stratospheric NO_x levels (the breakdown product of N₂O that destroys stratospheric ozone). This could not only delay the recovery of the stratospheric ozone layer, but might also prevent a return to pre-1980 global average ozone concentrations, a key goal of the international ozone regime. Accordingly, we think this will highlight the importance of reducing emissions of all major greenhouse gas emissions, including N₂O, and not just a singular policy focus on CO₂.