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On 13 October 1908, Fritz Haber filed his patent on the ``synthesis of ammonia from its elements'' for which he was later awarded the 1918 Nobel Prize in Chemistry. A hundred years on we live in a world transformed by and highly dependent upon Haber-Bosch nitrogen.
On 13 October 1908, Fritz Haber led his patent on the synthesis of ammonia from its elements
for which he was later awarded the 1918 Nobel Prize in Chemistry. A hundred years on we live in a
world transformed by and highly dependent upon HaberBosch nitrogen.
How a century of ammonia synthesis
changed the world
Although over 78% of the atmosphere
is composed of nitrogen, it exists in its
chemically and biologically unusable
gaseous form. Haber discovered how
ammonia, a chemically reactive, highly
usable form of nitrogen, could be
synthesized by reacting atmospheric
dinitrogen with hydrogen in the presence
of iron at high pressures and temperatures.
Today, this reaction is known as the
Haber–Bosch process: Fritz Haber was the
inventor who created the breakthrough
and laid the foundations for high-
pressure chemical engineering, but it was
Carl Bosch who subsequently developed
it on an industrial scale, for which he
was awarded a Nobel Prize in 1931. e
importance of Haber’s discovery cannot
be overestimated — as a result, millions of
people have died in armed conicts over
the past 100 years, but, at the same time,
billions of people have been fed.
In his Nobel lecture, Haber explained
that his main motivation for synthesizing
ammonia from its elements was the
growing demand for food, and the
concomitant need to replace the nitrogen
lost from elds owing to the harvesting
of crops: “it was clear that the demand
for xed nitrogen, which at the beginning
of this century could be satised with a
few hundred thousand tons a year, must
increase to millions of tons”
. We now
know that his vision was right: the current
worldwide use of fertilizer nitrogen is
about 100 Tg N per year.
Haber’s other motivation, not
mentioned in his lecture, was to provide
the raw material for explosives to be used
in weapons, which requires large amounts
of reactive nitrogen. Haber’s discovery has
therefore had a major inuence on both
World Wars and all subsequent conicts.
In addition, the large-scale production
of ammonia has facilitated the industrial
manufacture of a large number of
chemical compounds and many synthetic
products. us the Haber–Bosch process,
with its impacts on agriculture, industry
and the course of modern history, has
literally changed the world.
What Fritz Haber could not
foresee, however, was the cascade of
environmental changes, including the
increase in water and air pollution, the
perturbation of greenhouse-gas levels and
the loss of biodiversity that was to result
from the colossal increase in ammonia
production and use that was to ensue
Here we reect on the inuence that
Haber’s invention has had on society
over the last century, both the benets
and unintended consequences. And,
based on dierent scenarios of future
nitrogen fertilizer use, we discuss some
of the challenges likely to be faced by our
‘nitrogen economy’ in the next 100 years.
Up until the rst decades of the
twentieth century, many industrial
processes were dependent on limited
natural reservoirs of reactive nitrogen,
particularly Peruvian guano, Chilean
saltpeter and sal ammoniac extracted
from coal. Early attempts to x nitrogen
from the atmosphere were inecient and
energetically expensive. e Haber–Bosch
process has signicantly lower energy
requirements and was therefore
substantially cheaper, allowing it to form
the basis of an alternative expanding supply
of reactive nitrogen. Haber’s nitrogen has
since boosted the production of many
previously expensive or rare compounds,
such as dyes and articial bres, but it has
had its greatest impact on the production
of explosives and fertilizers
e central role that nitrogen has in the
manufacture of explosives is reected
not only in the Nobel prizes awarded to
Haber and Bosch, but in the very origin
of the Nobel Prize itself. Alfred Nobel’s
Agricultural production for food and fuel has increased in the past few years; for example, oilseed rape as
shown here.
Gert van duinen
636 nature geoscience | VOL 1 | ADVANCE ONLINE PUBLICATION |
wealth was built on the development of
safe methods for using nitroglycerine,
and his patents for dynamite and gelignite
eventually nanced the Nobel Foundation.
As a German patriot, Haber was keen to
develop explosives and other chemical
weapons, which to his mind were more
humane, because they “would shorten the
. e need to improve munitions
supplies was in reality a central motivation
for industrial ammonia production.
With the blockade of Chilean saltpeter
supplies during the First World War, the
Haber–Bosch process provided Germany
with a home supply of ammonia.
is was oxidized to nitric acid and
used to produce ammonium nitrate,
nitroglycerine, TNT (trinitrotoluene) and
other nitrogen-containing explosives.
Haber’s discovery therefore fuelled the
First World War, and, ironically, prevented
what might have been a swi victory for
the Allied Forces. Since then, reactive
nitrogen produced by the Haber–Bosch
process has become the central foundation
of the worlds ammunition supplies. As
such, its use can be directly linked to
100–150 million deaths in armed conicts
throughout the twentieth century
At the same time, the Haber–Bosch
process has facilitated the production of
agricultural fertilizers on an industrial
scale, dramatically increasing global
agricultural productivity in most regions
of the world
(Fig. 1). We estimate that the
number of humans supported per hectare
of arable land has increased from 1.9 to
4.3 persons between 1908 and 2008. is
increase was mainly possible because of
Haber–Bosch nitrogen.
Smil estimated that at the end of
the twentieth century, about 40% of
the world’s population depended on
fertilizer inputs to produce food
It is dicult to quantify this number
precisely because of changes in cropping
methods, mechanization, plant breeding
and genetic modication, and so on.
However, an independent analysis, based
on long-term experiments and national
statistics, concluded that about 30–50% of
the crop yield increase was due to nitrogen
application through mineral fertilizer
It is important to note that these
estimates are based on global averages,
which hide major regional dierences.
In Europe and North America, increases
in agricultural productivity have been
matched by luxury levels of nitrogen
consumption owing to an increase in the
consumption of meat and dairy products,
which require more fertilizer nitrogen
to produce — this is partly reected in
the global increase in per capita meat
consumption (Fig. 1). In contrast, the
latest Food and Agriculture Organization
report shows that approximately 850
million people remain undernourished
Overall, we suggest that nitrogen
fertilizer has supported approximately
27% of the world’s population over
the past century, equivalent to around
4 billion people born (or 42% of the
estimated total births) since 1908 (Fig. 1).
For these calculations, we assumed
that, in the absence of additional
nitrogen, other improvements would
have accounted for a 20% increase in
productivity between 1950 and 2000.
Consistent with Smil
, we estimate,
that by 2000, nitrogen fertilizers were
responsible for feeding 44% of the world’s
population. Our updated estimate for
2008 is 48% so the lives of around
half of humanity are made possible by
Haber–Bosch nitrogen.
In addition, fertilizer is required
for bioenergy and biofuel production.
Currently, bioenergy contributes 10%
of the global energy requirement,
whereas biofuels contribute 1.5%. ese
energy sources do not therefore have a
large inuence on global fertilizer use
However, with biofuel production set to
increase, the inuence of Haber–Bosch
nitrogen will only grow.
Together with the role of reactive
nitrogen in ammunition supplies, these
gures provide an illustration of the
huge importance of industrial ammonia
production for society, although, on
balance, it remains questionable to what
extent the consequences can be considered
as benecial.
Of the total nitrogen manufactured by
the Haber–Bosch process, approximately
80% is used in the production of
agricultural fertilizers
. However, a large
proportion of this nitrogen is lost to the
environment: in 2005, approximately
100 Tg N from the Haber–Bosch
process was used in global agriculture,
whereas only 17 Tg N was consumed
by humans in crop, dairy and meat
. Even recognizing the other
non-food benefits of livestock (for
example, transport, hides, wool and so
on), this highlights an extremely low
nitrogen-use efficiency in agriculture
(the amount of nitrogen retrieved in
food produced per unit of nitrogen
applied). In fact, the global nitrogen-
use efficiency of cereals decreased
from ~80% in 1960 to ~30% in 2000
The smaller fraction of Haber–Bosch
nitrogen used in the manufacture of
other chemical compounds (~20%) has
1900 1950 2000
World population (millions)
% World population/
Average fertilizer input (kg N ha
Meat production (kg person
World population
World population
(no Haber Bosch nitrogen)
% World population
fed by Haber Bosch nitrogen
Average fertilizer input
Meat production
Figure 1 Trends in human population and nitrogen use throughout the twentieth century. Of the total world
population (solid line), an estimate is made of the number of people that could be sustained without reactive
nitrogen from the Haber–Bosch process (long dashed line), also expressed as a percentage of the global
population (short dashed line). The recorded increase in average fertilizer use per hectare of agricultural land
(blue symbols) and the increase in per capita meat production (green symbols) is also shown.
nature geoscience | VOL 1 | ADVANCE ONLINE PUBLICATION | 637
an uncertain fate, with its escape into the
environment depending on the life-cycle
of the product.
A recent study suggested that
approximately 40% of fertilizer nitrogen
lost to the environment is denitried back
to unreactive atmospheric dinitrogen
In principle this loss is environmentally
benign, although it represents a waste
of the energy used in the Haber–Bosch
process equivalent to at least 32 MJ kg
xed, or about 1% of the global primary
energy supply. However, the rest
of the excess nitrogen escapes into
environmental reservoirs, where it
cascades through atmospheric, terrestrial,
aquatic and marine pools before
eventually being denitried or stored as
fossil reactive nitrogen. In principle, one
molecule of reactive nitrogen can have
multiple eects during its lifetime in the
cascade. Understanding this cascade is
therefore essential for the development of
eective abatement measures
The influence of Haber–Bosch
nitrogen on the global nitrogen cycle
can be seen in present-day atmospheric
and aquatic nitrogen pools. Emissions
of NO and NH
to the atmosphere
have increased about fivefold since
pre-industrial times
. Atmospheric
nitrogen deposition in the absence of
human influence is ~0.5 kg N ha
or less, but in large regions of the world,
average atmospheric deposition rates
exceed 10 kg N ha
, exceeding
natural rates by more than an order
of magnitude. Much of this reactive
nitrogen is deposited in nitrogen-limited
ecosystems, leading to unintentional
fertilization and loss of terrestrial
biodiversity. Similarly, the transfer
of reactive nitrogen from terrestrial
to coastal systems has doubled since
pre-industrial times
. As with terrestrial
ecosystems, many of the coastal
ecosystems receiving increased nitrogen
loadings are nitrogen-limited, leading to
algal blooms and a decline in the quality
of surface and ground waters.
In addition to these ecosystem-level
disturbances, reactive nitrogen alters
the balance of greenhouse gases,
enhances tropospheric ozone, decreases
stratospheric ozone, increases soil
acidification and stimulates the
formation of secondary particulate
matter in the atmosphere, all of which
have negative effects on people and
the environment.
The effects of reactive nitrogen
on the environment can be mitigated
through several intervention strategies,
which should focus on reducing the
creation of reactive nitrogen, increasing
the efficiency with which it is used,
or converting it back to atmospheric
dinitrogen. Such strategies could include
increasing the efficiency of nitrogen use
in food production, altering human diets
and improving the treatment of human
and animal waste
Another unintended, but positive,
environmental consequence of the
Haber–Bosch process may be an increase
in the amount of carbon sequestrated
in non-agricultural ecosystems, due to
an increase in atmospheric nitrogen
deposition. Recent debate has focused
on the response of forests
, where
the strength of this fertilization eect is
contentious. Estimates of the amount of
additional carbon stored per kilogram
of nitrogen deposited range from 40
to 400 kilograms of carbon, although
the most recent estimates suggest that
the largest values are unlikely
. In
the meantime, further eorts are being
directed to understand the overall eect
of reactive nitrogen on the greenhouse
gas balance, including its interactions
with nitrous oxide, methane, ozone
and aerosols
We project global nitrogen fertilizer
demand over the next century on the
basis of the four storylines developed for
the Intergovernmental Panel on Climate
Change Special Report on Emission
Scenarios (SRES)
. The storylines reflect
varying economic, demographic and
technological developments. The A1
storyline assumes a world of very rapid
economic growth, a global population
that peaks mid-century, and rapid
introduction of new and more efficient
technologies. B1 describes a convergent
world, with the same global population
as A1, but with more rapid changes in
economic structures towards a service
and information economy. B2 describes
a world with intermediate population
and economic growth, emphasizing
local solutions to economic, social
and environmental sustainability.
A2 describes a very heterogeneous
world with high population growth,
slow economic development and slow
technological change. We consider the
following five parameters to be the
main drivers of the estimated trends
in fertilizer use, and we apply a subset
of these parameters to the respective
scenarios (see Fig. 2).
(1) Population growth is the main driver
behind the increase in nitrogen fertilizer
use. e SRES population projections
range between 7 (B1) and 15 billion people
(A2) in 2100. Recent research suggests
that global fertility rates will continue to
decrease. As a consequence, population
growth is expected to eventually halt
(2) The potential for increasing
yield per hectare is large, and could
allow food output to keep pace with
population increases, without requiring
an increase in cropping area. At the same
time, an increase in fertilizer efficiency
is expected. In agreement with Smil
, we
assume that nitrogen management can
be improved, resulting in a 50% increase
in nitrogen-use efficiency, thus reducing
nitrogen application.
1900 1950 2000 2050 2100 A1 A2 B1 B1
Tg N
Diet optimization
Food equity
Population growth
A1 + biofuel
Tilman et al.
Tubiello and Fischer
FAO (baseline)
FAO (improved)
Figure 2 Global nitrogen fertilizer consumption scenarios (left) and the impact of individual drivers on 2100
consumption (right). This resulting consumption is always the sum (denoted at the end points of the respective
arrows) of elements increasing as well as decreasing nitrogen consumption. Other relevant estimates
presented for comparison. The A1, B1, A2 and B2 scenarios draw from the assumptions of the IPCC emission
storylines as explained in the text.
638 nature geoscience | ADVANCE ONLINE PUBLICATION |
3) Further demand on agriculture may
be posed by biofuel production, calling
for an expansion of crop land as well
as an increase in nitrogen demand.
In the technology-oriented global’
scenario (A1), we use the Organisation
for Economic Co-operation and
Development estimate of the maximum
potential land available for bioenergy
(0.74 Gha), which represents an
extension equal to half the current
cropland area
(4) Large parts of the world population
are deprived of valuable animal protein.
We assume that food equity will increase
worldwide meat consumption to the
level observed in developed countries.
Increased meat production will increase
nitrogen usage because of the additional
nitrogen required to produce animal
feed, and the inefficiency of nitrogen
use in meat-based diets relative to
plant- based diets.
(5) We assume that human diets will be
optimized to improve nitrogen-conversion
eciency in the production cycle.
Specically, we assume that the ratio of
meat protein to milk protein (currently
about 2:1) will be reversed (1:2), as the
nitrogen-to-protein conversion ratio is
higher in milk than meat
Our projections are well within the
low estimates provided by the Food and
Agriculture Organization
, and some
higher estimates in scientic literature
which suggest a two- to threefold increase
in nitrogen fertilizer use by the second
half of the twenty-rst century, assuming
continuation of past practices. In all our
scenarios, anticipated improvement in
eciency will compensate for much of the
increase in fertilizer demand. Furthermore,
we do not expect global protein supply
to improve towards ‘food equity’ in the
scenarios predicting high population
growth (A2 and B2 projections). us the
drivers towards high nitrogen use will not
occur simultaneously, leading to smaller
dierences in annual nitrogen demand
(100–150 Tg N) than would be expected
from population projection alone. Only
when bioenergy calls for a large increase
in crop production is fertilizer nitrogen
demand expected to double to nearly
200 Tg N per year. Despite the uncertainty
and the many important drivers not
included, all scenarios point towards an
increase in future production of reactive
nitrogen. is will further increase the
nitrogen pressures on the environment,
with uneven distribution only exacerbating
the problem regionally.
It is appropriate to mark a century of
Haber’s invention. Given its multiple roles
in military security, food production,
biofuels and a host of adverse environmental
impacts, we argue that today’s society can be
considered dependent on a nitrogen-based
economy. It is important to note, however,
that the benets of Haber–Bosch nitrogen
are not available to all people of the world,
owing to nancial, geographical and
political constraints. It is therefore essential
to provide the infrastructure to supply
nitrogen where it is needed, and to use it in a
sustainable way.
Fritz Haber aimed to inuence the
course of history by providing strategic
advantages for his country in terms of food
and military security. His invention for
synthesizing ammonia exceeded
expectations, substantially altering the
course of the planet throughout the
twentieth century. But, as illustrated in our
future scenarios, there is a high probability
that the unintended environmental
consequences will not be reduced over
the coming decades. Each of the main
human drivers, such as growth in the
population, improvement of the worlds
food supply and the use of biomass
to provide energy, will lead to further
increases in the demand for nitrogen, and
will more than compensate for expected
improvements in eciency. In the
worst-case scenario, we will move towards
a nitrogen-saturated planet, with polluted
air, reduced biodiversity, increased human
health risks and an even more perturbed
greenhouse-gas balance.
Food and military security were the
key objectives for Haber. For us, global
environmental sustainability must surely
be the main driver for future innovation.
Examples of key advances to aim for include
improving nitrogen-use eciency and
reducing dependency on nitrogen-intensive
biofuels, as well as developing a
comprehensive supply of protein and
amino acids with greatly improved
eciency compared with traditional
agricultural systems.
It will be interesting to look back a
century from now: will another patent have
changed the world to the same extent as the
one Fritz Haber led a hundred years ago?
Published online: 28 September 2008.
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We acknowledge nancing from the European Commission
for the NitroEurope Integrated Project, the European Science
Foundation for the NinE programme and the COST programme
(European Cooperation in the eld of Scientic and Technical
Research) for COST 729. is article was prepared as a
contribution to the International Nitrogen Initiative and the
Task Force on Reactive Nitrogen of the United Nations Economic
Commission for Europe.
Jan Willem Erisman
*, Mark A. Sutton
James Galloway
, Zbigniew Klimont
and Wilfried Winiwarter
Energy Research Center of the Netherlands,
ECN, PO Box 1, 1755 ZG Petten,
the Netherlands;
Centre for Ecology and Hydrology,
Edinburgh Research Station, Bush Estate,
Penicuik, Midlothian, EH26 0QB, UK;
Environmental Sciences, University
of Virginia, PO Box 400123,
291 McCormick Rd, Charlottesville,
Virginia 22904, USA;
International Institute for Applied Systems
Analysis (IIASA), Schlossplatz 1,
A-2361 Laxenburg, Austria;
Austrian Research Centers, Donau-City Str. 1,
A-1220 Vienna, Austria.
nature geoscience | ADVANCE ONLINE PUBLICATION | 639
... Next to sulfuric acid, ammonia (NH 3 ) is the second most produced chemical in the world and is one of the essential commodities in our lives [1]. NH 3 is employed in various fields, encompassing fertilizers, plastics, textiles, explosives, pharmaceuticals, dyes, and refrigerants [2][3][4]. In addition, it is considered an attractive hydrogen energy carrier due to its high gravimetric hydrogen density (17.8 wt%) and high volumetric energy density (4.32 kWh/L), similar to methanol [1,[4][5][6]. ...
... The NH 3 production via the HB process requires high temperatures (400-500 • C) and high pressures (150-300 atm) using Fe-based catalysts [12,13], consuming more than 1% of the total global energy [14]. Additionally, the hydrogen molecules used in the HB process are mainly produced from the steam methane reforming (SMR) of fossil fuels, emitting approximately 1.67 tons of CO 2 per ton of NH 3 [15,16]. Considering that the annual production of NH 3 by the process was 235 million tons in 2021, the amount of CO 2 emission from this process is Although the NRR process is environmentally benign with zero carbon emissions and reduced energy consumption, challenging issues, such as insufficient faradaic efficiency (FE) and low NH3 yield for practical application, still exist. ...
... In the associative distal pathway (Figure 2b), the N 2 molecule reaches the catalyst surface and is adsorbed in end-on mode. The remote N atom (i.e., the distal N atom) is hydrogenated first and released as NH 3 . Another N atom remaining on the catalyst surface is continuously reduced to pro-duce the second NH 3 . ...
Full-text available
Electrochemical nitrogen reduction (NRR) has attracted much attention as a promising technique to produce ammonia at ambient conditions in an environmentally benign and less energy-consuming manner compared to the current Haber–Bosch process. However, even though much research on the NRR catalysts has been conducted, their low selectivity and reaction rate still hinder the practical application of the NRR process. Among various catalysts, transition metal nitride (TMN)-based catalysts are expected to be promising catalysts for NRR. This is because the NRR process can proceed via the unique Mars–Van Krevelen (MvK) mechanism with a compressed competing hydrogen evolution reaction. However, a controversial issue exists regarding the origin of ammonia produced on TMN-based catalysts. The instability of the TMN-based catalysts can lead to ammonia generation from lattice nitrogen instead of supplied N2 gas. Thus, this review summarizes the recent progress of TMN-based catalysts for NRR, encompassing the NRR mechanism, synthetic routes, characterizations, and controversial opinions. Furthermore, future perspectives on producing ammonia electrochemically using TMN-based catalysts are provided.
... Molecular nitrogen (N2) accounts for more than 99% of global nitrogen (1) but is extremely chemically stable and thus cannot be directly utilized unless fixed by alternating its oxidation state into bioavailable forms (2). Since the advent of energy-intensive Haber-Bosch (HB) process early in the 20 th century and up to the present time, N2 on Earth has been predominantly 10 fixed in the form of ammonia (NH3), which has largely shaped our world and its heavy dependence on NH3 (3). However, the intensive reaction conditions (ca. 100 bar and 500°C), severe environmental pollution (>1% of the global carbon emission) and high consumption of fossil fuel (1%-2% of global energy consumption) in the HB process are becoming increasingly crucial for the global sustainable development and urge novel strategies for N2 15 fixation under mild conditions (4,5). ...
... Extensive research is being done in search of alternative strategies for N2 fixation to NH3, including electrocatalytic (6, 7), photocatalytic (8), biological (9), and plasma-based (10) methods, but none of these methods have yet been able to rival the overall performance of HB process with regard to the cost efficiency, scalability and selectivity of NH3 production (6,11,12). 20 In parallel, it is also of paramount interest to explore alternative molecular mechanisms of fixing N2 that would obviate the production of NH3 and thus alleviate the current dependence of society on NH3 (3,(13)(14)(15). The global production and utilization of NH3 are associated with a great number of critical issues, including its severe environmental implications, toxicity, flammability, explosion hazards, corrosiveness, difficulties of 25 transportation and storage, etc, which are increasingly at odds with the paradigm of sustainable development (3). ...
... 20 In parallel, it is also of paramount interest to explore alternative molecular mechanisms of fixing N2 that would obviate the production of NH3 and thus alleviate the current dependence of society on NH3 (3,(13)(14)(15). The global production and utilization of NH3 are associated with a great number of critical issues, including its severe environmental implications, toxicity, flammability, explosion hazards, corrosiveness, difficulties of 25 transportation and storage, etc, which are increasingly at odds with the paradigm of sustainable development (3). In fact, the prodigious amounts of NH3 utilized on Earth at present time are to a larger degree dictated by the scarcity of alternative routes of N2 fixation rather than by the intrinsic usability of NH3. ...
Full-text available
The growth and sustainable development of humanity is heavily dependent upon the process of fixing nitrogen (N2) to ammonia (NH3). However, the currently adopted methods are associated with severe environmental hazards and tremendous energy costs, which limit their sustainability and profitability. Herein we discovered a catalyst-free disproportionation reaction of N2 by water dimer radical cation, (H2O)2+, which occurs under mild ambient conditions via distinctive HONH-HNOH+ intermediate to yield economically valuable nitroxyl (HNO) and hydroxylamine (NH2OH) products, in alternative to NH3. Calculations suggest that the reaction is prompted by the coordination of electronically excited N2 with (H2O)2+ in its two-center-three-electron (2c-3e) configuration. The ambient one-step fixation of N2 into HNO and NH2OH with high selectivity offers great profitability and total avoidance of polluting emissions, such as CO2 or NOy, thus giving an entirely new look and perspectives to the problem of green N2 fixation.
... N fertilization has increased by an order of magnitude in the last six decades [66]. Converting atmospheric N 2 to ammonium as a source for N fertilization has been the main process responsible for the increased agricultural yield since the end of World War II [24]. The average increase in yield during 1930-2000 attributable to inputs of N fertilizers generally ranged from about 40-64% in temperate climates (USA and England) and tended to be much higher in the tropics [24,82]. ...
... Converting atmospheric N 2 to ammonium as a source for N fertilization has been the main process responsible for the increased agricultural yield since the end of World War II [24]. The average increase in yield during 1930-2000 attributable to inputs of N fertilizers generally ranged from about 40-64% in temperate climates (USA and England) and tended to be much higher in the tropics [24,82]. Higher N inputs to improve crop yield should be possible without exceeding the critical regional N concentration in runoff in some areas of the world, such as southeastern Asia, Latin America, Oceania, the Caribbean and sub-Saharan Africa (except South Africa) [8]. ...
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The massive use of fertilizers during the last decades allowed a great increase in the global capacity of food production. However, in the last years, several studies highlight the inefficiency and country asymmetries in the use of these fertilizers that generated environmental problems, soil nutritional imbalances and not optimal food production. We have aimed to summarize this information and identify and disentangle the key caveats that should be solved. Inadequate global management of fertilization produces areas with serious nutrient deficits in croplands linked with insufficient access to fertilizers that clearly limit food production, and areas that are overfertilized with the consequent problems of environmental pollution affecting human health. A more efficient use of nitrogen (N), phosphorus (P) and potassium (K) fertilizers for food security while preserving the environment is thus needed. Nutrient imbalances, particularly the disequilibrium of the N:P ratio due to the unbalanced release of N and P from anthropogenic activities, mainly by crop fertilization and expanding N-fixing crops that have continuously increased the soil N:P ratio, is another issue to resolve. This imbalance has already affected several terrestrial and aquatic ecosystems, altering their species composition and functionality and threatening global biodiversity. The different economic and geopolitical traits of these three main macronutrient fertilizers must be considered. P has the fewest reserves, depending mostly on mineable efforts, with most of the reserves concentrated in very few countries (85% in Morocco). This problem is a great concern for the current and near-future access to P for low-income countries. N is instead readily available due to the well-established and relatively low-cost Haber–Bosch synthesis of ammonium from atmospheric N2, which is increasingly used, even in some low-income countries producing an increasing imbalance in nutrient ratios with the application of P and K fertilizers. The anthropogenic inputs of these three macronutrients to the environment have reached the levels of the natural fluxes, thereby substantially altering their global cycles. The case of the excess of N fertilization is especially paradigmatic in several areas of the world, where continental water sources have become useless due to the higher nitrate concentrations. The management of N, P and K fertilizers is thus in the center of the main dichotomy between food security and environmentally driven problems, such as climate change or eutrophication/pollution. Such a key role demands new legislation for adopting the well-known and common-sense 4R principle (right nutrient source at the right rate, right time and right place) that would help to ensure the appropriate use of nutrient resources and the optimization of productivity.
... Nowadays, ammonia has become one of the most widely used industrial chemicals for economic development [1][2][3]. However, to date, ammonia synthesis heavily relies on the energy-consuming and capital-intensive Haber-Bosch process [4][5][6][7]. With the reduction in fossil fuels, and the focus on increased greenhouse gas emissions, more sustainable and economical methods of ammonia production are needed to support the growing demand [8]. ...
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Electrochemical nitrogen reduction reaction (ENRR) offers a sustainable alternative to the environmentally hazardous Haber–Bosch process for producing ammonia. However, it suffers from an unsatisfactory performance due to its limited active sites and competitive hydrogen evolution reaction. Herein, we design a hydrophobic oleylamine-modified zeolitic imidazolate framework-coated nanoporous silver composite structure (NPS@O-ZIF). The composite achieves a high ammonia yield of (41.3 ± 0.9) μg·h−1·cm−2 and great Faradaic efficiency of (31.7 ± 1.2)%, overcoming the performances of NPS@ZIF and traditional silver nanoparticles@O-ZIF. Our strategy affords more active sites and accessible channels for reactant species due to the porous structure of NPS cores and restrains the evolution of hydrogen by introducing the hydrophobic molecule coated on the ZIF surfaces. Hence, the design of the hydrophobic core–shell composite catalyst provides a valuably practical strategy for ENRR as well as other water-sensitive reactions.
... Mineral fertilisers contribute greatly to increasing food production globally (Erisman et al., 2008). Without them, normal crop yield would feed only about 2-3 billion people (Bindraban et al., 2018). ...
The fertiliser value chain in Ghana faces many challenges that limit its potential contribution to food production and food security in the country. This has necessitated discussions on the need to establish a multi-stakeholder platform to address existing value chain challenges. In preparation for this platform, this study conducted 31 interviews and identified 24 stakeholder groups in the fertiliser value chain using stakeholder analysis and social network analysis. We found that while many of the public sector stakeholders have a lot of power and show high interest in the fertiliser value chain, they usually face resource constraints in exercising their duties. Conversely, a majority of the private sector stakeholders have a high interest in fertilisers but do not have much power to influence decisions. Also, development partners are very powerful and resourceful, but practically, they have a temporary presence in the value chain. The study subsequently combined the results from stakeholder analysis and social network analysis and identified 19 critical stakeholders out of the initial 24 who can highly influence the initial planning and subsequent success of the platform. Lastly, the study identified challenges that the platform may face and the conditions to put in place to avoid/address these identified challenges. Overall, the study concludes that if the identified critical stakeholders are engaged and the platform clearly outlines its objectives and vision, it can address the challenges in the fertiliser value chain, contribute to the development of the general agriculture sector and improve food production and food security in Ghana.
... However, mitigating climate change and improving food security are two of the world's most challenging issues (Shakoor et al. 2021). Since the invention of the Haber-Bosch process, N use in agriculture has increased substantially to feed the rapidly expanding population (Billen et al. 2013;Erisman et al. 2008;Smith et al. 2020). By 2050, the world's population is expected to touch 10 billion (Shakoor et al. 2020), and global N consumption has been projected to escalate from 142 to 169% by 2050 to achieve a 100-110% increase in crop yields (IFA, 2013). ...
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Nitrification inhibitors (NIs), especially dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP), have been extensively investigated to mitigate nitrogen (N) losses from the soil and thus improve crop productivity by enhancing N use efficiency. However, to provide crop and soil-specific guidelines about using these NIs, a quantitative assessment of their efficacy in mitigating gaseous emissions, worth for nitrate leaching, and improving crop productivity under different crops and soils is yet required. Therefore, based upon 146 peer-reviewed research studies, we conducted a meta-analysis to quantify the effect of DCD and DMPP on gaseous emissions, nitrate leaching, soil inorganic N, and crop productivity under different variates. The efficacy of the NIs in reducing the emissions of CO2, CH4, NO, and N2O highly depends on the crop, soil, and experiment types. The comparative efficacy of DCD in reducing N2O emission was higher than the DMPP under maize, grasses, and fallow soils in both organic and chemical fertilizer amended soils. The use of DCD was linked to increased NH3 emission in vegetables, rice, and grasses. Depending upon the crop, soil, and fertilizer type, both the NIs decreased nitrate leaching from soils; however, DMPP was more effective. Nevertheless, the effect of DCD on crop productivity indicators, including N uptake, N use efficiency, and biomass/yield was higher than DMPP due to certain factors. Moreover, among soils, crops, and fertilizer types, the response by plant productivity indicators to the application of NIs ranged between 35 and 43%. Overall, the finding of this meta-analysis strongly suggests the use of DCD and DMPP while considering the crop, fertilizer, and soil types. Graphical Abstract
The electrochemical synthesis of ammonia is highly dependent on the coupling reaction between nitrate and water, for which an electrocatalyst with a multifunctional interface is anticipated to promote the deoxygenation and hydrogenation of nitrate with water. Herein, by engineering the surface of bimetallic Ni/Co-MOFs (NiCoBDC) with hydrogen-substituted graphdiyne (HsGDY), a hybrid nanoarray of NiCoBDC@HsGDY with a multifunctional interface has been achieved toward scale-up of the nitrate-to-ammonia conversion. On the one hand, a partial electron transfers from Ni2+ to the coordinatively unsaturated Co2+ on the surface of NiCoBDC, which not only promotes the deoxygenation of *NO3 on Co2+ but also activates the water-dissociation to *H on Ni2+. On the other hand, the conformal coated HsGDY facilitates both electrons and NO3- ions gathering on the interface between NiCoBDC and HsGDY, which moves forward the rate-determining step from the deoxygenation of *NO3 to the hydrogenation of *N with both *H on Ni2+ and *H2O on Co2+. As a result, such a NiCoBDC@HsGDY nanoarray delivers high NH3 yield rates with Faradaic efficiency above 90% over both wide potential and pH windows. When assembled into a galvanic Zn-NO3- battery, a power density of 3.66 mW cm-2 is achieved, suggesting its potential in the area of aqueous Zn-based batteries.
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Temperate and boreal forests in the Northern Hemisphere cover an area of about 2 × 107 square kilometres and act as a substantial carbon sink (0.6-0.7 petagrams of carbon per year). Although forest expansion following agricultural abandonment is certainly responsible for an important fraction of this carbon sink activity, the additional effects on the carbon balance of established forests of increased atmospheric carbon dioxide, increasing temperatures, changes in management practices and nitrogen deposition are difficult to disentangle, despite an extensive network of measurement stations. The relevance of this measurement effort has also been questioned, because spot measurements fail to take into account the role of disturbances, either natural (fire, pests, windstorms) or anthropogenic (forest harvesting). Here we show that the temporal dynamics following stand-replacing disturbances do indeed account for a very large fraction of the overall variability in forest carbon sequestration. After the confounding effects of disturbance have been factored out, however, forest net carbon sequestration is found to be overwhelmingly driven by nitrogen deposition, largely the result of anthropogenic activities. The effect is always positive over the range of nitrogen deposition covered by currently available data sets, casting doubts on the risk of widespread ecosystem nitrogen saturation under natural conditions. The results demonstrate that mankind is ultimately controlling the carbon balance of temperate and boreal forests, either directly (through forest management) or indirectly (through nitrogen deposition).
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A doubling in global food demand projected for the next 50 years poses huge challenges for the sustainability both of food production and of terrestrial and aquatic ecosystems and the services they provide to society. Agriculturalists are the principal managers of global useable lands and will shape, perhaps irreversibly, the surface of the Earth in the coming decades. New incentives and policies for ensuring the sustainability of agriculture and ecosystem services will be crucial if we are to meet the demands of improving yields without compromising environmental integrity or public health.
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Land and ocean uptake of carbon dioxide plays a critical role in determining atmospheric carbon dioxide levels. Future increases in nitrogen deposition have been predicted to increase the size of these terrestrial and marine carbon sinks, but although higher rates of nitrogen deposition might enhance carbon uptake in northern and tropical forests, they will probably have less of an impact on ocean sink strength. Combined, the land and ocean sinks may sequester an additional 10% of anthropogenic cabon emissions by 2030 owing to increased nitrogen inputs, but a more conservative estimate of 1 to 2% is more likely. Thus nitrogen-induced increases in the strength of land and ocean sinks are unlikely to keep pace with future increases in carbon dioxide.
Nutrient inputs in crop production systems have come under increased scrutiny in recent years because of the potential for environmental impact from inputs such as N and P. The benefits of nutrient inputs are often minimized in discussions of potential risk. The purpose of this article is to examine existing data and approximate the effects of nutrient inputs, specifically from commercial fertilizers, on crop yield. Several long-term studies in the USA, England, and the tropics, along with the results from an agricultural chemical use study and nutrient budget information, were evaluated. A total of 362 seasons of crop production were included in the long-term study evaluations. Crops utilized in these studies included corn (Zea mays L.), wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], rice (Oryza sativa L.), and cowpea [Vigna unguiculata (L.) Walp.]. The average percentage of yield attributable to fertilizer generally ranged from about 40 to 60% in the USA and England and tended to be much higher in the tropics. Recently calculated budgets for N, P, and K indicate that commercial fertilizer makes up the majority of nutrient inputs necessary to sustain current crop yields in the USA. The results of this investigation indicate that the commonly cited generalization that at least 30 to 50% of crop yield is attributable to commercial fertilizer nutrient inputs is a reasonable, if not conservative estimate.
Human production of food and energy is the dominant continental process that breaks the triple bond in molecular nitrogen (N2) and creates reactive nitrogen (Nr) species. Circulation of anthropogenic Nr in Earth’s atmosphere, hydrosphere, and biosphere has a wide variety of consequences, which are magnified with time as Nr moves along its biogeochemical pathway. The same atom of Nr can cause multiple effects in the atmosphere, in terrestrial ecosystems, in freshwater and marine systems, and on human health. We call this sequence of effects the nitrogen cascade. As the cascade progresses, the origin of Nr becomes unimportant. Reactive nitrogen does not cascade at the same rate through all environmental systems; some systems have the ability to accumulate Nr, which leads to lag times in the continuation of the cascade. These lags slow the cascade and result in Nr accumulation in certain reservoirs, which in turn can enhance the effects of Nr on that environment. The only way to eliminate Nr accumulation and stop the cascade is to convert Nr back to nonreactive N2.
The industrial synthesis of ammonia from nitrogen and hydrogen has been of greater fundamental importance to the modern world than the invention of the airplane, nuclear energy, space flight, or television. The expansion of the world's population from 1.6 billion people in 1900 to today's six billion would not have been possible without the synthesis of ammonia. In Enriching the Earth, Vaclav Smil begins with a discussion of nitrogen's unique status in the biosphere, its role in crop production, and traditional means of supplying the nutrient. He then looks at various attempts to expand natural nitrogen flows through mineral and synthetic fertilizers. The core of the book is a detailed narrative of the discovery of ammonia synthesis by Fritz Haber -- a discovery scientists had sought for over one hundred years -- and its commercialization by Carl Bosch and the chemical company BASF. Smil also examines the emergence of the large-scale nitrogen fertilizer industry and analyzes the extent of global dependence on the Haber-Bosch process and its biospheric consequences. Finally, it looks at the role of nitrogen in civilization and, in a sad coda, describes the lives of Fritz Haber and Carl Bosch after the discovery of ammonia synthesis.
IPCC Special Report on Emissions Scenarios Contents: Foreword Preface Summary for policymakers Technical Summary Chapter 1: Background and Overview Chapter 2: An Overview of the Scenario Literature Chapter 3: Scenario Driving Forces Chapter 4: An Overview of Scenarios Chapter 5: Emission Scenarios Chapter 6: Summary Discussions and Recommendations
In a recent study, Magnani et al. report how atmospheric nitrogen deposition drives stand-lifetime net ecosystem productivity (NEPav) for midlatitude forests, with an extremely high C to N response (725 kg C kg−1 wet-deposited N for their European sites). We present here a re-analysis of these data, which suggests a much smaller C : N response for total N inputs. Accounting for dry, as well as wet N deposition reduces the C : N response to 177 : 1. However, if covariance with intersite climatological differences is accounted for, the actual C : N response in this dataset may be <70 : 1. We then use a model analysis of 22 European forest stands to simulate the findings of Magnani et al. Multisite regression of simulated NEPav vs. total N deposition reproduces a high C : N response (149 : 1). However, once the effects of intersite climatological differences are accounted for, the value is again found to be much smaller, pointing to a real C : N response of about 50–75 : 1.