More sustainable agriculture by global redistribution of nitrogen fertilizer
Models reveal that a homogeneous global distribution of nitrogen fertilizer would significantly reduce worldwide fertilization and the resulting pollution of the environment
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WORLDWIDE GRAIN FARMING IS ASSOCIATED WITH A HIGH GLOBAL CONSUMPTION OF NITROGEN FERTILIZER. KIT RESEARCHERS FOUND THAT A GLOBAL REDISTRIBUTION WOULD HAVE A POSITIVE IMPACT ON THE ENVIRONMENT. (PHOTO: MARKUS BREIG, KIT)
view moreCREDIT: MARKUS BREIG, KIT
Models Reveal that a Homogeneous Global Distribution of Nitrogen Fertilizer Would Significantly Reduce Worldwide Fertilization and the Resulting Pollution of the EnvironmentModels Reveal that a Homogeneous Global Distribution of Nitrogen Fertilizer Would Significantly Reduce Worldwide Fertilization and the Resulting Pollution of the EnvironmentAbout 60 percent of worldwide nitrogen fertilizer consumption are presently used for growing crops, such as corn, wheat, or rice. These plants need nitrogen fertilizers to grow and produce bigger harvests. However, large quantities of the fertilizer enter the ground and groundwater or are emitted into the atmosphere in the form of nitrous oxide. This pollutes the environment and contributes to the loss of biological diversity, to climate change, and to the degradation of the ozone layer. This problem is particularly serious in the big cultivation areas of North America, Europe, and East Asia, where comparably large amounts of nitrogen fertilizer are used. KIT researchers recently modeled the effect of a worldwide redistribution of nitrogen fertilizer use. They simulated various fertilizer quantities at different locations and calculated the total production of corn, wheat, and rice between 2015 and 2030 using the biogeochemical model LandscapeDNDC. “Our work was based on the question of how we can produce sufficient food without exceeding environmental boundaries,” says Dr. Andrew Smerald from the Atmospheric Environmental Research Department of KIT’s Institute of Meteorology and Climate Research (IMK-IFU), KIT’s Campus Alpine in Garmisch-Partenkirchen.
Grain Production Level Could Be Maintained with a Far Smaller Global Use of Fertilizer
“Our models show that worldwide consumption of nitrogen fertilizer could be reduced by 32 percent by a more homogeneous distribution. The current level of grain production would remain unaffected,” Smerald says. “For this, nitrogen fertilizer would have to be redistributed from traditional cultivation areas in China, North America, and Europe to less used areas, such as Sub-Saharan Africa.“ Then, the increased production in these regions would compensate decreased production in other regions. As a result, nitrogen fertilizer use for wheat and corn production would be reduced by 45 and 33 percent, respectively, without influencing worldwide production quantities. Moreover, nitrate leaching would be reduced by 71 percent for wheat and 63 percent for corn.
Models reveal that worldwide redistribution of nitrogen fertilizer consumption would positively affect nitrous oxide emissions. (Photo: Andrew Smerald, KIT)
“According to our study, a more homogeneous distribution of nitrogen fertilizer across global croplands would reduce our dependence on the presently existing granaries and decrease nitrogen pollution in East Asia and other strongly fertilized regions,” Smerald says. Another advantage would consist in the fact that crops could be cultivated closer to the place of their consumption. Increased harvests in Africa would help the continent reach self-sufficiency.
Original Publication
Andrew Smerald, David Kraus, Jaber Rahimi, Kathrin Fuchs, Ralf Kiese, Klaus Butterbach-Bahl, & Clemens Scheer: A redistribution of nitrogen fertiliser across global croplands can help achieve food security within environmental boundaries. Communications Earth & Environment, 2023. DOI 10.1038/s43247-023-00970-8. https://www.nature.com/articles/s43247-023-00970-8
Models reveal that worldwide redistribution of nitrogen fertilizer consumption would positively affect nitrous oxide emissions. (Photo: Andrew Smerald, KIT)
CREDIT
Andrew Smerald, KIT
More about the KIT Climate and Environment Center
Being “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility, and information. For this, about 9,800 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 22,300 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life. KIT is one of the German universities of excellence.
About 60 percent of worldwide nitrogen fertilizer consumption are presently used for growing crops, such as corn, wheat, or rice. These plants need nitrogen fertilizers to grow and produce bigger harvests. However, large quantities of the fertilizer enter the ground and groundwater or are emitted into the atmosphere in the form of nitrous oxide. This pollutes the environment and contributes to the loss of biological diversity, to climate change, and to the degradation of the ozone layer. This problem is particularly serious in the big cultivation areas of North America, Europe, and East Asia, where comparably large amounts of nitrogen fertilizer are used. KIT researchers recently modeled the effect of a worldwide redistribution of nitrogen fertilizer use. They simulated various fertilizer quantities at different locations and calculated the total production of corn, wheat, and rice between 2015 and 2030 using the biogeochemical model LandscapeDNDC. “Our work was based on the question of how we can produce sufficient food without exceeding environmental boundaries,” says Dr. Andrew Smerald from the Atmospheric Environmental Research Department of KIT’s Institute of Meteorology and Climate Research (IMK-IFU), KIT’s Campus Alpine in Garmisch-Partenkirchen.
Grain Production Level Could Be Maintained with a Far Smaller Global Use of Fertilizer
“Our models show that worldwide consumption of nitrogen fertilizer could be reduced by 32 percent by a more homogeneous distribution. The current level of grain production would remain unaffected,” Smerald says. “For this, nitrogen fertilizer would have to be redistributed from traditional cultivation areas in China, North America, and Europe to less used areas, such as Sub-Saharan Africa.“ Then, the increased production in these regions would compensate decreased production in other regions. As a result, nitrogen fertilizer use for wheat and corn production would be reduced by 45 and 33 percent, respectively, without influencing worldwide production quantities. Moreover, nitrate leaching would be reduced by 71 percent for wheat and 63 percent for corn.
“According to our study, a more homogeneous distribution of nitrogen fertilizer across global croplands would reduce our dependence on the presently existing granaries and decrease nitrogen pollution in East Asia and other strongly fertilized regions,” Smerald says. Another advantage would consist in the fact that crops could be cultivated closer to the place of their consumption. Increased harvests in Africa would help the continent reach self-sufficiency.
Original Publication
Andrew Smerald, David Kraus, Jaber Rahimi, Kathrin Fuchs, Ralf Kiese, Klaus Butterbach-Bahl, & Clemens Scheer: A redistribution of nitrogen fertiliser across global croplands can help achieve food security within environmental boundaries. Communications Earth & Environment, 2023. DOI 10.1038/s43247-023-00970-8. https://www.nature.com/articles/s43247-023-00970-8
More about the KIT Climate and Environment Center
Being “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility, and information. For this, about 9,800 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 22,300 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life. KIT is one of the German universities of excellence.
JOURNAL
Communications Earth & Environment
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A redistribution of nitrogen fertiliser across global croplands can help achieve food security within environmental boundaries
Nitrogen enrichment delays the emergence of an aridity-induced threshold for plant biomass
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ARIDITY THRESHOLDS FOR MEASURED (A) ABOVEGROUND BIOMASS (N = 1353) AND (D) ROOT-SHOOT RATIO (N = 3093). SOLID RED LINES REPRESENT THE LINEAR FITS ON BOTH SIDES OF EACH THRESHOLD. THE RED NUMBERS AND VERTICAL DASHED LINES REPRESENT THE IDENTIFIED ARIDITY THRESHOLDS. PLANT BIOMASS DATA WERE LOG-TRANSFORMED TO CONFORM TO NORMALITY. THE VIOLIN DIAGRAMS IN PANELS B AND E SHOW BOOTSTRAPPED SLOPES OF THE PREDICTED FITTED TREND AT THE THRESHOLD OF THE TWO REGRESSIONS EXISTING AT EACH SIDE OF THE THRESHOLD (PURPLE BEFORE THE THRESHOLD, RED AFTER THE THRESHOLD). THE VIOLIN DIAGRAMS IN PANELS C AND F SHOW BOOTSTRAPPED INTERCEPTS. THE ASTERISKS REPRESENT A SIGNIFICANT DIFFERENCE BEFORE AND AFTER THE ARIDITY THRESHOLD AT P < 0.001 USING THE MANN-WHITNEY U TEST.
view moreCREDIT: ©SCIENCE CHINA PRESS
This study is led by Dr. Jian-Sheng Ye from Lanzhou University, China.
Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown, however, whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and productivity of vegetation, such as elevated CO2 and nitrogen (N) enrichment.
In this study, researchers gathered over 5000 field measurements of plant biomass. Their findings revealed that crossing an aridity threshold of ~0.50, which marks the transition from dry sub-humid to semi-arid climates, led to abrupt declines in aboveground biomass (AGB) and progressive increases in the root: shoot ratios. This has a profound impact on carbon storage and its distribution within these ecosystems.
Notably, N enrichment was found to significantly increase aboveground biomass and delay the onset of the aridity threshold from 0.49 to 0.55. However, increased CO2 levels did not alter the observed aridity threshold.
Looking ahead to the year 2100, under a high greenhouse gases emissions scenario, researchers predicted a minor 0.3% net increase in the global land area that surpasses the aridity threshold when considering the effects of N enrichment. In contrast, without factoring in N enrichment, this net increase was projected to reach 2.9%. This suggests that N enrichment can mitigate the negative impacts of rising aridity on plant biomass in drylands.
These findings carry significant implications for our ability to improve forecasts of vegetation responses to change in aridity, nitrogen and CO2.
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See the article: https://doi.org/10.1093/nsr/nwad242
JOURNAL
National Science Review
DOI
Measured plant aboveground biomass (a) and comparisons of aridity threshold values (b) under ambient and nitrogen (N) enrichment treatments (n = 167 sites). Remotely sensed and random forest model-simulated leaf area index (c), and comparisons of aridity threshold values (d) under high (401 ppm) and low (341 ppm) CO2 levels. The two comparisons are based on paired datasets of high vs. low N/CO2 levels. Data were log-transformed to conform to normality. Box plots in (b) and (d) show the median, upper and lower quartiles, with outlier values represented by black dots. Different letters indicate significant differences in aridity thresholds between high versus low N levels (p < 0.001).
Panels A and B show the frequency distributions of changes in aridity and nitrogen deposition, respectively. Panel C shows predicted future changes in land area crossing the observed aridity threshold; the comparisons between scenarios considering (a, c, e, g, i, k) and not including (b, d, f, h, j, l) the effects of nitrogen deposition are also shown.
Panels A and B show the frequency distributions of changes in aridity and nitrogen deposition, respectively. Panel C shows predicted future changes in land area crossing the observed aridity threshold; the comparisons between scenarios considering (a, c, e, g, i, k) and not including (b, d, f, h, j, l) the effects of nitrogen deposition are also shown.
Changes in AGB by 2100 under the RCP8.5 scenario due to aridity changes (a), nitrogen deposition (b) and the combination of both (c). The overall changes in AGB are summarized in panel d. We include land areas with aridity ≥ 0, i.e., zones where annual precipitation is ≤ potential evapotranspiration (excluding croplands).
Changes in AGB by 2100 under the RCP8.5 scenario due to aridity changes (a), nitrogen deposition (b) and the combination of both (c). The overall changes in AGB are summarized in panel d. We include land areas with aridity ≥ 0, i.e., zones where annual precipitation is ≤ potential evapotranspiration (excluding croplands).
CREDIT
©Science China Press
©Science China Press
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