scholarly journals The influence of tillage and fertilizer on the flux and source of nitrous oxide with reference to atmospheric variation using laser spectroscopy

2021 ◽  
Author(s):  
Peggy H. Ostrom ◽  
Samuel DeCamp ◽  
Hasand Gandhi ◽  
Joshua Haslun ◽  
Nathaniel E. Ostrom
Keyword(s):  
Nitrous Oxide ◽  
Panicum Virgatum ◽  
Fertilizer Treatment ◽  
Site Preference ◽  
Soil Microbial ◽  
The Third ◽  
No Till ◽  
Wide Range ◽  
Atmospheric Variation ◽  
Fertilization Experiments

AbstractNitrous oxide (N2O) is the third most important long-lived greenhouse gas and agriculture is the largest source of N2O emissions. Curbing N2O emissions requires understanding influences on the flux and sources of N2O. We measured flux and evaluated microbial sources of N2O using site preference (SP; the intramolecular distribution of 15N in N2O) in flux chambers from a grassland tilling and agricultural fertilization experiments and atmosphere. We identified values greater than that of the average atmosphere to reflect nitrification and/or fungal denitrification and those lower than atmosphere as increased denitrification. Our spectroscopic approach was based on an extensive calibration with 18 standards that yielded SP accuracy and reproducibility of 0.7 ‰ and 1.0 ‰, respectively, without preconcentration. Chamber samples from the tilling experiment taken ~ monthly over a year showed a wide range in N2O flux (0–1.9 g N2O-N ha−1 d−1) and SP (− 1.8 to 25.1 ‰). Flux and SP were not influenced by tilling but responded to sampling date. Large fluxes occurred in October and May in no-till when soils were warm and moist and during a spring thaw, an event likely representing release of N2O accumulated under snow cover. These high fluxes could not be ascribed to a single microbial process as SP differed among chambers. However, the year-long SP and flux data for no-till showed a slight direct relationship suggesting that nitrification increased with flux. The comparative data in till showed an inverse relationship indicating that high flux events are driven by denitrification. Corn (Zea mays) showed high fluxes and SP values indicative of nitrification ~ 4 wk after fertilization with subsequent declines in SP indicating denitrification. Although there was no effect of fertilizer treatment on flux or SP in switchgrass (Panicum virgatum), high fluxes occurred ~ 1 month after fertilization. In both treatments, SP was indicative of denitrification in many instances, but evidence of nitrification/fungal denitrification also prevailed. At 2 m atmospheric N2O SP had a range of 31.1 ‰ and 14.6 ‰ in the grassland tilling and agricultural fertilization experiments, respectively. These data suggest the influence of soil microbial processes on atmospheric N2O and argue against the use of the global average atmospheric SP in isotopic modeling approaches.

scholarly journals Estimation of isotope variation of N<sub>2</sub>O during denitrification by <i>Pseudomonas aureofaciens</i> and <i>Pseudomonas chlororaphis</i>: implications for N<sub>2</sub>O source apportionment

2018 ◽  
Vol 15 (12) ◽  
pp. 3873-3882 ◽  
Author(s):  
Joshua A. Haslun ◽  
Nathaniel E. Ostrom ◽  
Eric L. Hegg ◽  
Peggy H. Ostrom
Keyword(s):  
Nitrous Oxide ◽  
Electron Donor ◽  
Isotope Effects ◽  
Microbial Processes ◽  
Site Preference ◽  
N2o Emissions ◽  
Pseudomonas Chlororaphis ◽  
Fractionation Factor ◽  
N2o Production ◽  
Soil Microbial

Abstract. Soil microbial processes, stimulated by agricultural fertilization, account for 90 % of anthropogenic nitrous oxide (N2O), the leading source of ozone depletion and a potent greenhouse gas. Efforts to reduce N2O flux commonly focus on reducing fertilization rates. Management of microbial processes responsible for N2O production may also be used to reduce N2O emissions, but this requires knowledge of the prevailing process. To this end, stable isotopes of N2O have been applied to differentiate N2O produced by nitrification and denitrification. To better understand the factors contributing to isotopic variation during denitrification, we characterized the δ15N, δ18O and site preference (SP; the intramolecular distribution of 15N in N2O) of N2O produced during NO3- reduction by Pseudomonas chlororaphis subsp. aureofaciens and P. c. subsp. chlororaphis. The terminal product of denitrification for these two species is N2O because they lack the gene nitrous oxide reductase, which is responsible for the reduction of N2O to N2. In addition to species, treatments included electron donor (citrate and succinate) and electron donor concentration (0.01, 0.1, 1 and 10 mM) as factors. In contrast to the expectation of a Rayleigh model, all treatments exhibited curvilinear behaviour between δ15N or δ18O and the extent of the reaction. The curvilinear behaviour indicates that the fractionation factor changed over the course of the reaction, something that is not unexpected for a multi-step process such as denitrification. Using the derivative of the equation, we estimated that the net isotope effects (η) vary by as much as 100 ‰ over the course of a single reaction, presenting challenges for using δ15N and δ18O as apportionment tools. In contrast, SP for denitrification was not affected by the extent of the reaction, the electron donor source or concentration, although the mean SP of N2O produced by each species differed. Therefore, SP remains a robust indicator of the origin of N2O. To improve apportionment estimates with SP, future studies could evaluate other factors that contribute to the variation in SP.

The Colonial Documentary Film in South and South-East Asia

2017 ◽  
Keyword(s):  
East Asia ◽  
Subject Matter ◽  
Documentary Film ◽  
East Asian ◽  
South East Asia ◽  
Post Colonial ◽  
Historical Perspectives ◽  
The Third ◽  
Wide Range ◽  
Global Understanding

Writing from a wide range of historical perspectives, contributors to the anthology shed new light on historical, theoretical and empirical issues pertaining to the documentary film, in order to better comprehend the significant transformations of the form in colonial, late colonial and immediate post-colonial and postcolonial times in South and South-East Asia. In doing so, this anthology addresses an important gap in the global understanding of documentary discourses, practices, uses and styles. Based upon in-depth essays written by international authorities in the field and cutting-edge doctoral projects, this anthology is the first to encompass different periods, national contexts, subject matter and style in order to address important and also relatively little-known issues in colonial documentary film in the South and South-East Asian regions. This anthology is divided into three main thematic sections, each of which crosses national or geographical boundaries. The first section addresses issues of colonialism, late colonialism and independence. The second section looks at the use of the documentary film by missionaries and Christian evangelists, whilst the third explores the relation between documentary film, nationalism and representation.

Duoethnography: A Polytheoretical Approach to (Re)Storing, (Re)Storying the Meanings That One Gives

2020 ◽  
pp. 396-423
Author(s):  
John Joseph Norris ◽  
Richard D. Sawyer
Keyword(s):  
Social Justice ◽  
Critical Theory ◽  
Third Space ◽  
The Third ◽  
The Core ◽  
Wide Range ◽  
Core Elements ◽  
Feminist Inquiry

This chapter summarizes the advancement of duoethnography throughout its fifteen-year history, employing examples from a variety of topics in education and social justice to provide a wide range of approaches that one may take when conducting a duoethnography. A checklist articulates what its cofounders consider the core elements of duoethnographies, additional features that may or may not be employed and how some studies purporting to be duoethnographies may not be so. The chapter indicates connections between duoethnography and a number of methodological concepts including the third space, the problematics of representation, feminist inquiry, and critical theory using published examples by several duoethnographers.

Nitrous oxide emissions from manured, no-till corn systems

2021 ◽  
Vol 119 (3) ◽  
pp. 405-421
Author(s):  
María A. Ponce de León ◽  
Curtis J. Dell ◽  
Heather D. Karsten
Keyword(s):  
Nitrous Oxide ◽  
Nitrous Oxide Emissions ◽  
No Till

scholarly journals Why and How to Switch to Genomic Selection: Lessons From Plant and Animal Breeding Experience

2021 ◽  
Vol 12 ◽  
Author(s):  
◽  
Aline Fugeray-Scarbel ◽  
Catherine Bastien ◽  
Mathilde Dupont-Nivet ◽  
Stéphane Lemarié
Keyword(s):  
Genetic Diversity ◽  
Genomic Selection ◽  
Plant Species ◽  
Animal Species ◽  
Animal Breeding ◽  
Breeding Cycle ◽  
Breeding Programs ◽  
The Third ◽  
Wide Range ◽  
Selection For

The present study is a transversal analysis of the interest in genomic selection for plant and animal species. It focuses on the arguments that may convince breeders to switch to genomic selection. The arguments are classified into three different “bricks.” The first brick considers the addition of genotyping to improve the accuracy of the prediction of breeding values. The second consists of saving costs and/or shortening the breeding cycle by replacing all or a portion of the phenotyping effort with genotyping. The third concerns population management to improve the choice of parents to either optimize crossbreeding or maintain genetic diversity. We analyse the relevance of these different bricks for a wide range of animal and plant species and sought to explain the differences between species according to their biological specificities and the organization of breeding programs.

scholarly journals Effect of 50 Years of No-Tillage, Stubble Retention, and Nitrogen Fertilization on Soil Respiration, Easily Extractable Glomalin, and Nitrogen Mineralization

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 151
Author(s):  
Pramod Jha ◽  
Kuntal M. Hati ◽  
Ram C. Dalal ◽  
Yash P. Dang ◽  
Peter M. Kopittke ◽  
...  
Keyword(s):  
Soil Respiration ◽  
N Mineralization ◽  
Positive Impact ◽  
N Fertilization ◽  
N Fertilizer ◽  
N Availability ◽  
Soil Microbial ◽  
Stubble Retention ◽  
No Till

In subtropical regions, we have an incomplete understanding of how long-term tillage, stubble, and nitrogen (N) fertilizer management affects soil biological functioning. We examined a subtropical site managed for 50 years using varying tillage (conventional till (CT) and no-till (NT)), stubble management (stubble burning (SB) and stubble retention (SR)), and N fertilization (0 (N0), 30 (N30), and 90 (N90) kg ha−1 y−1) to assess their impact on soil microbial respiration, easily extractable glomalin-related soil protein (EEGRSP), and N mineralization. A significant three-way tillage × stubble × N fertilizer interaction was observed for soil respiration, with NT+SB+N0 treatments generally releasing the highest amounts of CO2 over the incubation period (1135 mg/kg), and NT+SR+N0 treatments releasing the lowest (528 mg/kg). In contrast, a significant stubble × N interaction was observed for both EEGRSP and N mineralization, with the highest concentrations of both EEGRSP (2.66 ± 0.86 g kg−1) and N mineralization (30.7 mg/kg) observed in SR+N90 treatments. Furthermore, N mineralization was also positively correlated with EEGRSP (R2 = 0.76, p < 0.001), indicating that EEGRSP can potentially be used as an index of soil N availability. Overall, this study has shown that SR and N fertilization have a positive impact on soil biological functioning.

scholarly journals Continuous measurements of nitrous oxide isotopomers during incubation experiments

2016 ◽  
Author(s):  
Malte Winther ◽  
David Balslev-Harder ◽  
Søren Christensen ◽  
Anders Priemé ◽  
Bo Elberling ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Isotope Effect ◽  
Atmospheric Chemistry ◽  
Isotope Effects ◽  
Denitrifying Bacteria ◽  
Central Position ◽  
Site Preference ◽  
Continuous Measurements ◽  
Incubation Experiments

Abstract. Nitrous oxide (N2O) is an important and strong greenhouse gas in the atmosphere and part of a feed-back loop with climate. N2O is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N2O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. The position of the isotope 15N in the linear N = N = O molecule can be distinguished between the central or terminal position (isotopomers of N2O). It has been demonstrated that nitrifying and denitrifying microbes have a different relative preference for the terminal and central position. Therefore, measurements of the site preference in N2O can be used to determine the source of N2O i.e. nitrification or denitrification. Recent instrument development allows for continuous (on the order of days) position dependent δ15N measurements at N2O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N2O) and P. chlororaphis (only producing N2O). The continuous position dependent measurements reveal the transient pattern (KNO3 to N2O and N2, respectively), which can be compared to previous reported site preference (SP) values. We find bulk isotope effects of −5.5 ‰ ± 0.9 for P. chlororaphis. For P. fluorescens, the bulk isotope effect during production of N2O is −50.4 ‰ ± 9.3 and 8.5 ‰ ± 3.7 during N2O reduction. The values for P. fluorescens are in line with earlier findings, whereas the values for P. chlororaphis are larger than previously published δ15Nbulk measurements from production. The calculations of the SP isotope effect from the measurements of P. chlororaphis result in values of −6.6 ‰ ± 1.8. For P. fluorescens, the calculations results in SP values of −5.7 ‰ ± 5.6 during production of N2O and 2.3 ‰ ± 3.2 during reduction of N2O. In summary, we implemented continuous measurements of N2O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better understanding of denitrifying bacteria and N2O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the Globe.

scholarly journals The Culture of the Sakas of Semirechye: Contemporary State and Current Issues of Study

2021 ◽  
Vol 20 (3) ◽  
pp. 22-35
Author(s):  
Ernar A. Estemesov
Keyword(s):  
Iron Age ◽  
Social Groups ◽  
Archaeological Sites ◽  
Radiocarbon Dates ◽  
Funeral Rites ◽  
The Third ◽  
Urgent Task ◽  
Wide Range ◽  
Burial Mounds ◽  
Second Category

Purpose. The article describes the history and analysis of the main issues in the study of archaeological sites of the Saka period in Semirechye. They are presented by three main types on this territory: burial and memorial complexes, settlements and hoards. The first type of monuments includes numerous burial mounds, where the elite burials of “royal” type and ordinary burials are located. Both social groups are combined by the unity of funeral rites, and the main differences are the complexity of architecture, memorial practices, and richness of burial equipment in the “royal” type burial mounds. The second category of monuments is presented by the settlements that are mostly small in size. The constructions like half dugouts were discovered on them, which gave a rich ceramic material. The third type of monuments of the Saka period in Semirechye includes numerous hoards of bronze items. Some of them are represented by the cult objects (sacrificial tables, lamps and cauldrons) that mark the places of worship. A significant percentage of the hoards contain items of weapons, horse equipment and household purposes and, apparently, serve as offerings to the spirits. However, despite the considerable progress in the study of the Saka monuments of the Semirechye Region, the main problem is their cultural attribution at this time. Some researchers suggest that the independent Saka archaeological culture was formed and developed on the territory of Semirechye in the Early Iron Age, while others believe that the Saka monuments of this region belong to the broader historical and cultural community that also covers the neighboring regions of Kyrgyzstan and Xinjiang. Results Another important issue in the study of the Saka sites of Semirechye is to clarify the chronology of burial and memorial complexes. Up to now, the significant database of radiocarbon dates has been accumulated, which allows us to consider the chronological positions of a wide range of monuments in a new way. It was of great importance to obtain such dates from several burials of Karatuma necropolis, which showed that it belonged to the Saka period, since burial monuments of this appearance are traditionally dated back to the Wusun period. Conclusion. The necessity of solution of these problems is an urgent task for further research of burial and settlement objects of the Saka period in this region.

scholarly journals Perancangan dan Analisis Perbandingan Implementasi OSPF pada Jaringan IPv4 dan IPv6

2014 ◽  
Vol 2 (1) ◽  
pp. 40
Author(s):  
PAULINE RAHMIATI ◽  
DWI ARYANTA ◽  
TAUFIQ AGUNG PRIYADI
Keyword(s):  
Network Design ◽  
Shortest Path ◽  
Routing Protocol ◽  
Convergence Time ◽  
The Third ◽  
Wide Range ◽  
Packet Tracer ◽  
Maximum Limit ◽  
Better Than

ABSTRAKOSPF (Open Shortest Path First) adalah suatu routing protokol bersifat terbuka dan didukung oleh berbagai perangkat network. IPv4 telah mencapai batas maksimum dalam jumlah alamat sehingga IPv6 merupakan solusi dalam hal tersebut. Seperti IPv4, IPv6 juga sudah mulai diimplementasikan untuk routing protokol OSPF, oleh karena itu pada penelitian ini akan dirancang suatu routing protokol OSPF IPv6 dan sebagai bahan perbandingan akan dibandingkan dengan OSPF IPv4. Software Cisco Packet Tracer 5.3 digunakan untuk mensimulasikan perancangan jaringan yang dibuat. Pada penelitian ini akan dibandingkan 2 buah jaringan berbasis routing protokol OSPF, yaitu OSPF untuk IPv4 dan IPv6. Skenario pertama dilakukan 100 kali dalam 5 kasus untuk mengetahui nilai delay OSPF IPv4 dan OSPF IPv6. Skenario kedua dilakukan pemutusan link dilakukan sebanyak 30 kali, hal yang dilihat dari pengujian ini adalah hasil trace route dari cost yang ada. Skenario ketiga dilakukan dengan mengamati waktu konvergensi dari OSPF IPv4 dan IPv6. Secara keseluruhan nilai delay OSPF IPv6 lebih kecil dibandingkan dengan OSPF IPv4 sebesar 3-6%, Trace route dan nilai cost pada OSPF IPv6 dan OSPF IPv4 sama tetapi nilai delay OSPF IPv6 lebih kecil sebesar 3-6% dan waktu konvergensi OSPF IPv4 bernilai sama dengan OSPF IPv6 yaitu 10 detik.Kata kunci: OSPF, IPv4, Ipv6, delay, konvergensiABSTRACTOSPF (Open Shortest Path First) is a routing protocol that opened and supported by a wide range of network devices. IPv4 has reached the maximum limit on the number of addresses that IPv6 are a solution in this case. Same as IPv4, IPv6 also has begun to be implemented for the OSPF routing protocol, therefore this study wiould design an IPv6 OSPF routing protocol and as a comparison will be compared to IPv4 OSPF. Cisco Packet Tracer 5.3 software was used to simulate the made network design. This research would compare two pieces of network-based routing protocol OSPF, OSPF for IPv4 and IPv6. The first scenario was done 100 times in of 5 cases to determine the value of delay OSPF OSPF IPv4 and IPv6. The second scenario was carried out link terminations 30 times, it was seen from the tests was the result of trace route from the existing cost. The third scenario was done by observed at the convergence time of OSPF IPv4 and IPv6. The overall delay value OSPF IPv6 better than IPv4 OSPF by 3-6%, the trace route and the OSPF cost value of IPv6 and IPv4 OSPF were same but delay OSPF IPv6 was better 3-6% and convergence time was the same as IPv4 OSPF OSPF IPv6 as 10 seconds.Keywords: OSPF, IPv4, IPv6, delay, convergence

scholarly journals STRUKTUR KOMUNITAS MIKROBA TANAH DAN IMPLIKASINYA DALAM MEWUJUDKAN SISTEM PERTANIAN BERKELANJUTAN

el–Hayah ◽  
2012 ◽  
Vol 1 (4) ◽  
Author(s):  
Prihastuti Prihastuti
Keyword(s):  
Microbial Community ◽  
Microbial Diversity ◽  
Microbial Communities ◽  
Soil Microbial Community ◽  
Soil Microbial Communities ◽  
Organic Soil ◽  
Plant Type ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Wide Range

<p>Soils are made up of organic and an organic material. The organic soil component contains all the living creatures in the soil and the dead ones in various stages of decomposition.  Biological activity in soil helps to recycle nutrients, decompose organic matter making nutrient available for plant uptake, stabilize humus, and form soil particles.<br />The extent of the diversity of microbial in soil is seen to be critical to the maintenance of soil health and quality, as a wide range of microbial is involved in important soil functions.  That ecologically managed soils have a greater quantity and diversity of soil microbial. The two main drivers of soil microbial community structure, i.e., plant type and soil type, are thought to exert their function in a complex manner. The fact that in some situations the soil and in others the plant type is the key factor determining soil microbial diversity is related to their complexity of the microbial interactions in soil, including interactions between microbial and soil and microbial and plants. <br />The basic premise of organic soil stewardship is that all plant nutrients are present in the soil by maintaining a biologically active soil environment. The diversity of microbial communities has on ecological function and resilience to disturbances in soil ecosystems. Relationships are often observed between the extent of microbial diversity in soil, soil and plant quality and ecosystem sustainability. Agricultural management can be directed toward maximizing the quality of the soil microbial community in terms of disease suppression, if it is possible to shift soil microbial communities.</p><p>Keywords: structure, microbial, implication, sustainable agriculture<br /><br /></p>

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