scholarly journals The global nitrogen cycle in the twenty-first century

2013 ◽  
Vol 368 (1621) ◽  
pp. 20130164 ◽  
Author(s):  
David Fowler ◽  
Mhairi Coyle ◽  
Ute Skiba ◽  
Mark A. Sutton ◽  
J. Neil Cape ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Agricultural Land ◽  
Anthropogenic Activities ◽  
Terrestrial Ecosystems ◽  
Control Measures ◽  
First Century ◽  
Secondary Pollutants ◽  
Biological Nitrogen ◽  
Global Nitrogen Cycle

Global nitrogen fixation contributes 413 Tg of reactive nitrogen (N r ) to terrestrial and marine ecosystems annually of which anthropogenic activities are responsible for half, 210 Tg N. The majority of the transformations of anthropogenic N r are on land (240 Tg N yr −1 ) within soils and vegetation where reduced N r contributes most of the input through the use of fertilizer nitrogen in agriculture. Leakages from the use of fertilizer N r contribute to nitrate (NO 3 − ) in drainage waters from agricultural land and emissions of trace N r compounds to the atmosphere. Emissions, mainly of ammonia (NH 3 ) from land together with combustion related emissions of nitrogen oxides (NO x ), contribute 100 Tg N yr −1 to the atmosphere, which are transported between countries and processed within the atmosphere, generating secondary pollutants, including ozone and other photochemical oxidants and aerosols, especially ammonium nitrate (NH 4 NO 3 ) and ammonium sulfate (NH 4 ) 2 SO 4 . Leaching and riverine transport of NO 3 contribute 40–70 Tg N yr −1 to coastal waters and the open ocean, which together with the 30 Tg input to oceans from atmospheric deposition combine with marine biological nitrogen fixation (140 Tg N yr −1 ) to double the ocean processing of N r . Some of the marine N r is buried in sediments, the remainder being denitrified back to the atmosphere as N 2 or N 2 O. The marine processing is of a similar magnitude to that in terrestrial soils and vegetation, but has a larger fraction of natural origin. The lifetime of N r in the atmosphere, with the exception of N 2 O, is only a few weeks, while in terrestrial ecosystems, with the exception of peatlands (where it can be 10 2 –10 3 years), the lifetime is a few decades. In the ocean, the lifetime of N r is less well known but seems to be longer than in terrestrial ecosystems and may represent an important long-term source of N 2 O that will respond very slowly to control measures on the sources of N r from which it is produced.

scholarly journals Modeling biological nitrogen fixation in global natural terrestrial ecosystems

2020 ◽  
Vol 17 (13) ◽  
pp. 3643-3657
Author(s):  
Tong Yu ◽  
Qianlai Zhuang
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Cycle ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
Climatic Conditions ◽  
Fixation Rate ◽  
Observational Site ◽  
Biological Nitrogen ◽  
Global Nitrogen Cycle

Abstract. Biological nitrogen fixation plays an important role in the global nitrogen cycle. However, the fixation rate has been usually measured or estimated at a particular observational site. To quantify the fixation amount at the global scale, process-based models are needed. This study develops a biological nitrogen fixation model to quantitatively estimate the nitrogen fixation rate by plants in a natural environment. The revised nitrogen module better simulates the nitrogen cycle in comparison with our previous model that has not considered the fixation effects. The new model estimates that tropical forests have the highest fixation rate among all ecosystem types, which decreases from the Equator to the polar region. The estimated nitrogen fixation in global terrestrial ecosystems is 61.5 Tg N yr−1 with a range of 19.8–107.9 Tg N yr−1 in the 1990s. Our estimates are relatively low compared to some early estimates using empirical approaches but comparable to more recent estimates that involve more detailed processes in their modeling. Furthermore, the contribution of nitrogen made by biological nitrogen fixation depends on ecosystem type and climatic conditions. This study highlights that there are relatively large effects of biological nitrogen fixation on ecosystem nitrogen cycling. and the large uncertainty of the estimation calls for more comprehensive understanding of biological nitrogen fixation. More direct observational data for different ecosystems are in need to improve future quantification of fixation and its impacts.

Ecosystem scale evidence for the contribution of vanadium-based nitrogenase to biological nitrogen fixation

2020 ◽  
Author(s):  
Jean-Philippe Bellenger ◽  
Romain Darnajoux ◽  
Nicolas Magain ◽  
Marie Renaudin ◽  
Francois Lutzoni ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
High Latitude ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
The Arctic ◽  
Field Evidence ◽  
N Input ◽  
Vanadium Nitrogenase ◽  
Biological Nitrogen

<p>Nitrogen is the primary limiting nutrient in high latitude ecosystems. Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is an important source of new reactive nitrogen in pristine, high-latitude ecosystems. BNF is catalyzed by the enzyme nitrogenase, for which three isoforms have been described; the canonical molybdenum (Mo) nitrogenase which requires Mo in its active site and two alternative nitrogenases, the vanadium and iron-only nitrogenases. The low availability of Mo on land has been shown to limit BNF in many ecosystems from the tropical forest to the arctic tundra. Alternative nitrogenases have been suggested as viable alternatives to cope with Mo limitation of BNF, however, field data supporting this long-standing hypothesis have been lacking.</p><p>Here, we elucidated the contribution of the vanadium nitrogenase to BNF by cyanolichens across a 600 km latitudinal transect in eastern Canadian boreal forests. We report a widespread activity of the vanadium nitrogenase which contributed between 15 to 50% of total BNF rates on all sites. Vanadium nitrogenase contribution to BNF was more robust in the northern part of the transect. Vanadium nitrogenase contribution to BNF also changed during the growing season, with a three-fold increase between the early (May) and late (September) growing season. By including the contribution of the vanadium nitrogenase to BNF, estimates of new N input by cyanolichens increase by up to 30%, a significant change in these low N input ecosystems. Finally, we found that Mo availability was the primary driver for the contribution of the vanadium nitrogenase to BNF with a Mo threshold of ~ 250 ng.g<sub>lichen</sub><sup>-1</sup> for the onset of vanadium based BNF.</p><p>This study on N<sub>2</sub>-fixing cyanolichens provides extensive field evidence, at an ecosystem scale, that vanadium-based nitrogenase greatly contributes to BNF when Mo availability is limited. The results showcase the resilience of BNF to micronutrient limitation and reveal a strong link between the biogeochemical cycle of macro- and micronutrients in terrestrial ecosystems. Given widespread findings of Mo limitation of BNF in terrestrial ecosystems, additional consideration of vanadium-based BNF is required in experimental and modeling studies of terrestrial biogeochemistry.</p>

scholarly journals A roadmap for sampling and scaling biological nitrogen fixation in terrestrial ecosystems

2021 ◽  
Author(s):  
Fiona M Soper ◽  
Benton N Taylor ◽  
Joy B Winbourne ◽  
Michelle Y Wong ◽  
Katherine A Dynarski ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Biological Nitrogen

scholarly journals Global maps of cropland extent and change show accelerated cropland expansion in the twenty-first century

Nature Food ◽  
2021 ◽  
Author(s):  
Peter Potapov ◽  
Svetlana Turubanova ◽  
Matthew C. Hansen ◽  
Alexandra Tyukavina ◽  
Viviana Zalles ◽  
...  
Keyword(s):  
Time Series ◽  
Agricultural Land ◽  
Net Primary Production ◽  
Terrestrial Ecosystems ◽  
First Century ◽  
Tree Cover ◽  
Sustainable Food ◽  
Cropland Area ◽  
Per Capita ◽  
Twenty First Century

AbstractSpatiotemporally consistent data on global cropland extent is essential for tracking progress towards sustainable food production. In the present study, we present an analysis of global cropland area change for the first two decades of the twenty-first century derived from satellite data time-series. We estimate that, in 2019, the cropland area was 1,244 Mha with a corresponding total annual net primary production (NPP) of 5.5 Pg C year−1. From 2003 to 2019, cropland area increased by 9% and cropland NPP by 25%, primarily due to agricultural expansion in Africa and South America. Global cropland expansion accelerated over the past two decades, with a near doubling of the annual expansion rate, most notably in Africa. Half of the new cropland area (49%) replaced natural vegetation and tree cover, indicating a conflict with the sustainability goal of protecting terrestrial ecosystems. From 2003 to 2019, global per-capita cropland area decreased by 10% due to population growth. However, the per-capita annual cropland NPP increased by 3.5% as a result of intensified agricultural land use. The presented global, high-resolution, cropland map time-series supports monitoring of natural land appropriation at the local, national and international levels.

scholarly journals Impacts of biological nitrogen fixation on N<sub>2</sub>O emissions from global natural terrestrial ecosystem soils: An Analysis with a process-based biogeochemistry model

2019 ◽  
Author(s):  
Tong Yu ◽  
Qianlai Zhuang
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Climatic Conditions ◽  
N2o Emissions ◽  
Emission Model ◽  
Fixation Rate ◽  
Observational Site ◽  
Biological Nitrogen

Abstract. Biological nitrogen fixation plays an important role in the global nitrogen cycle. However, the fixation rate has been usually measured or estimated at a particular observational site. To quantify the fixation amount at the global scale, a process-based model is needed. This study develops a biological nitrogen fixation model and couples it with an extant biogeochemistry model of N2O emissions to examine the fixation rate and its effects on N2O emissions. The revised N2O emission model better matches the observed data in comparison with our previous model that has not considered the fixation effects. The new model estimates that tropical forests have the highest fixation rate among all ecosystem types, and decrease from the equator to the polar region. The estimated nitrogen fixation in global terrestrial ecosystems is 61.5 Tg N yr−1 with a range of 19.8–107.9 Tg N yr−1 in the 1990s. Our estimates are relatively low compared to some early estimates using empirical approaches, but comparable to more recent estimates that involve more detailed processes in their modeling. Furthermore, we estimate that the fixation contributes to −5 % to 20 % changes in N2O emissions compared to our previous estimates, depending on ecosystem types and climatic conditions. This study highlights that there are relatively large effects of the biological nitrogen fixation on ecosystem nitrogen cycling and soil N2O emissions and calls for more comprehensive understanding of biological nitrogen fixation and more observational data for different ecosystems to improve future quantification of the fixation and its impacts.

Biological nitrogen fixation by alternative nitrogenases in terrestrial ecosystems: a review

2020 ◽  
Vol 149 (1) ◽  
pp. 53-73 ◽  
Author(s):  
J. P. Bellenger ◽  
R. Darnajoux ◽  
X. Zhang ◽  
A. M. L. Kraepiel
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Biological Nitrogen

Compost Legacy Down-Regulates Biological Nitrogen Fixation in a Long-Term Field Experiment

2017 ◽  
Vol 109 (6) ◽  
pp. 2662-2669 ◽  
Author(s):  
Sieg Snapp ◽  
Brook Wilke ◽  
Lowell E. Gentry ◽  
Danielle Zoellner
Keyword(s):  
Nitrogen Fixation ◽  
Field Experiment ◽  
Biological Nitrogen Fixation ◽  
Biological Nitrogen ◽  
Term Field

scholarly journals Legume root nodule symbiosis: An evolving story in biology and biotechnology

2013 ◽  
Vol 35 (4) ◽  
pp. 14-18 ◽  
Author(s):  
Nicholas J. Brewin
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Root Nodule ◽  
Root Nodule Symbiosis ◽  
Evolution Of Life ◽  
Living Organisms ◽  
Life On Earth ◽  
Biological Nitrogen ◽  
Global Nitrogen Cycle ◽  
Nodule Symbiosis

The evolution of biological nitrogen fixation is central to the evolution of life on earth. Nitrogen is an essential component of proteins and nucleic acids and its restricted availability to living organisms has often been a major factor limiting growth. Despite the overwhelming abundance of N2 gas in the atmosphere, di-nitrogen is chemically inaccessible to most forms of life. For their growth and metabolism, most organisms use the ‘fixed’ forms of nitrogen, either as ammonium (NH4+) or as nitrate (NO3-), or derivatives thereof. However, the major input into the global nitrogen cycle is through the reductive process of biological nitrogen fixation which converts atmospheric N2 into ammonia (NH3). This process evolved in bacteria and/or archaea over 2.5 billion years ago while the planet still had a reducing atmosphere. Today, biological nitrogen fixation is still restricted to the bacteria and archaea. The legume root nodule symbiosis allows the host plant to benefit directly by association with soil bacteria, collectively termed rhizobia, which fix nitrogen as endosymbionts.

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