PDO cheeses and milks harbor startling microbial diversity

INRAE - National Research Institute for Agriculture, Food and Environment

 

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Roquefort, a PDO blue cheese.

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Credit: INRAE - NICOLAS Bertrand

Protected Designation of Origin (PDO) is an EU labelling scheme that guarantees the authentic regional identity of consumer food products. In France, 51 dairy products, including cheeses, butters, and creams, carry the PDO seal, a sign of artisanship and adherence to specifications related to production zones, production processes, and livestock diets, among other factors.

Cheese flavour, texture, and rind formation are all influenced by the bacteria, yeasts, and moulds introduced by milk sources and the fermentation process. These microbes can then go on to enrich the intestinal microbiota of cheese consumers.

For the first time ever, the microbial diversity of French PDO cheeses and their milk sources were studied by a team of researchers from INRAE, CEA, the French National Council for Dairy Products of Designated Origins (CNAOL), and the French National Interprofessional Centre for the Dairy Industry (CNIEL). As part of the MetaPDOcheese project (see sidebar below), the researchers worked with committed PDO stakeholders to collect samples from 386 farmers and cheese producers across France; they simultaneously gathered detailed information about cheese production methods.

They analysed 44 varieties of ripened cheese, all PDO. These cheeses were representative of seven cheese families (e.g., blue cheeses, pressed cooked cheeses) that are consumed worldwide. In the end, researchers from Genoscope[1] (CEA) sequenced the microbes in over 2,000 samples of French PDO cheeses and nearly 400 milk sources.

The results revealed the existence of extremely rich microbial assemblages: 820 bacterial species and 333 mould/yeast species in the cheeses, and 1,230 bacterial species and 1,367 mould/yeast species in the milk sources. A large proportion of the microbes in the cheeses likely come from the milk sources: there was overlap for approximately 42% of the bacterial species and 64% of the mould/yeast species.

After integrating the information on cheese production practices, the researchers found that species assemblages were influenced by variables such as geography, regional topography, and anthropogenic drivers—factors for which PDO is an aggregated proxy. From these findings, it is clear that regional artisanship helps cultivate the microbiota of cheeses.

This study has yielded valuable insights into the link between microbial diversity and the practices used to produce PDO cheeses, including how these dynamics may be affected by climate change.

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[1]A division of the CEA's François Jacob Institute of Biology. Specialising in environmental genomics, Genoscope develops bioinformatics methods and conducts biodiversity-focused research in genomics and metagenomics. It is also a national sequencing centre and thus makes its services available to the entire scientific community via France Génomique.

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A 2017 recipient of France Génomique funding for major sequencing projects, MetaPDOcheese is coordinated by INRAE (the SAYFOOD and UMRF research units). The project arose from brainstorming by the Microbial Ecosystems Group within the Joint Technical Network (RMT) for Terroir Cheeses. It has two main objectives: 1) to help those in PDO industries to better exploit omics approaches and 2) to answer ecological questions related to cheese and milk microbial assemblages. Ultimately, the project wants to identify techniques (e.g., technological tools, seeding practices) for fostering and safeguarding microbial diversity in cheese ecosystems, allowing stakeholders to develop methods for managing microbial resources in situ.

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Journal

ISME Communications

DOI

10.1093/ismeco/ycae095 

Article Title

A comprehensive, large-scale analysis of 'terroir' cheese and milk microbiota reveals profiles strongly shaped by both geographical and human factors

Article Publication Date

6-Aug-2024

Quality and safety analysis of plant extracts

Published by Dr Tao Lan in the journal Current Analytical Chemistry

News Release 9-Aug-2024

Bentham Science Publishers

As the demand for natural products continues to rise across pharmaceuticals, dietary supplements, and cosmetics, the importance of plant extracts as a key source of bioactive compounds has never been more evident. With increasing consumer focus on health, the discovery and utilization of new natural products are accelerating, contributing to a booming market. However, the diversity of plant extracts and the varied preparation processes have highlighted the need for standardized quality and safety measures globally.

Get more information here and contribute your research work on this trending topic: bit.ly/4fryXZj

This Special Issue addresses the urgent need for rigorous quality control in the industry. By bringing together research that delves into advanced analysis techniques, characterization methods, and the processes of extraction, isolation, purification, and analysis of plant extracts, the issue aims to establish a foundation for unified safety and efficacy standards. Researchers and industry experts are invited to contribute their findings to enhance the reliability and consistency of plant-based products.

Through this initiative, we seek to promote a collaborative effort within the scientific community to ensure that plant extracts meet the highest standards of quality and safety, ultimately benefiting consumers and advancing the fields of pharmaceuticals, dietary supplements, and cosmetics.

 

The dengue vaccine is effective and safe: confirmation from the first global meta-analysis

Università di Bologna

The Dengue vaccine has an efficacy rate of over 50% in reducing disease cases, with lasting effects and a very good safety profile. This is confirmed by the first global meta-analysis on the efficacy of TAK-003, better known as Qdenga: the only vaccine approved to date in Italy and many European countries for fighting Dengue. Published in the journal Vaccines, the study was conducted by scholars from the University of Bologna and the University of Ferrara.

"This is the first comprehensive global analysis and we are very pleased with the data," says Lamberto Manzoli, director of the School of Specialization in Hygiene and Preventive Medicine at the University of Bologna, who coordinated the study. "It was not a foregone conclusion: it took many years to develop a vaccine with such good results."

The Dengue virus, transmitted by certain species of mosquitoes, infects about 400 million people annually in the warmer regions of the planet, causing more than 3 million deaths. Climate change is also expanding the habitat of the mosquitoes that carry the virus, leading to new Dengue outbreaks in an increasing number of countries. Even in Italy, with the continuous rise in cases, the disease is a major health concern.

Currently, there is no effective therapy against the disease, and environmental remediation actions against mosquitoes cannot eliminate the risk of epidemics. The only prevention strategy is therefore vaccination: approved in Europe in December 2022, the vaccine TAK-003, better known as Qdenga, has shown very promising results. However, until now, a comprehensive estimate of its effectiveness and safety was not available.

Researchers therefore examined and cross-referenced data from the 19 scientific studies conducted so far on the vaccine, to find solid evidence of its ability to combat the disease. Overall, the cases of over 20,000 individuals involved in the various tests were considered, even more than a year after the last administration, both with a single dose and with both doses required for complete vaccination.

The results show that the vaccine reduces the risk of contracting the disease by over 50%, with a high safety profile. Among those who received both doses, more than 90% developed antibodies against Dengue, and the response is very positive even among those who received only one dose: more than 70% of adults and more than 90% of children and adolescents develop antibodies.

"Given the results in terms of safety, immunogenicity, and efficacy, the administration of two doses can undoubtedly be a key tool for Dengue prevention," confirms Maria Elena Flacco, director of the School of Specialization in Public Health at the University of Ferrara and the study's lead author. "The currently available vaccine can therefore be very useful not only for populations in endemic areas but also for travellers from non-risk areas."

The study was published in the journal Vaccines under the title "Immunogenicity, Safety and Efficacy of the Dengue Vaccine TAK-003: A Meta-Analysis." The authors are Alessandro Bianconi, Matteo Fiore, and Lamberto Manzoli from the University of Bologna (Department of Medical and Surgical Sciences), along with Maria Elena Flacco, Giovanni Cioni, Giovanna Letizia Calò, Gianmarco Imperiali, Vittorio Orazi, Marco Tiseo, Anastasia Troia, and Annalisa Rosso from the University of Ferrara (Department of Environmental and Prevention Sciences).

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Journal

Vaccines

DOI

10.3390/vaccines12070770 

Article Title

Immunogenicity, Safety and Efficacy of the Dengue Vaccine TAK-003: A Meta-Analysis

 

Liverpool team report pioneering plasma-catalytic process for CO2 hydrogenation to methanol under ambient conditions

University of Liverpool

Researchers at the University of Liverpool have achieved a significant milestone in the conversion of carbon dioxide (CO2) into valuable fuels and chemicals, marking an important step towards a sustainable net-zero economy.

In a paper published in the journal Chem, the team reports a pioneering plasma-catalytic process for the hydrogenation of CO2 to methanol at room temperature and atmospheric pressure.

This breakthrough addresses the limitations of traditional thermal catalysis, which often requires high temperatures and pressures, resulting in low CO2 conversion and methanol yield.

The novel process utilizes a bimetallic Ni-Co catalyst within a non-thermal plasma reactor to achieve an impressive single-pass 46% selectivity for methanol and 24% CO2 conversion at 35 °C and 0.1 MPa.

Non-thermal plasma, an ionized gas containing energetic electrons and reactive species, can activate strong chemical bonds of inert molecules like CO2, facilitating chemical reactions under mild conditions.

 In addition, plasma-based modular systems can be turned on and off instantly, offering great flexibility to use intermittent renewable electricity for decentralized production of fuels and chemicals.

Professor Xin Tu, Chair in Plasma Catalysis at the University of Liverpool, said: "Our work demonstrates that plasma catalysis offers a flexible and decentralized solution for CO2 hydrogenation to methanol under ambient conditions. Our recent techno-economic assessment also show that this process can significantly reduce the capital costs compared with traditional thermal catalytic CO2-to-methaol processes, providing a viable route for utilizing renewable energy sources in the production of synthetic fuels."

In situ plasma-coupled Fourier transform infrared (FTIR) characterization and density functional theory (DFT) calculations revealed that the bimetallic Ni-Co interface is the primary active center for methanol synthesis, with CO2 adsorption and hydrogenation occurring via the Eley-Rideal (E-R) mechanism to produce a variety of intermediates. Additionally, both the formate and carboxyl routes play a critical role in the formation of methanol, while the reverse water-gas shift (RWGS) and CO hydrogenation pathways were found to be less favorable on the Ni-Co sites. The precise control of Ni-Co sites in bimetallic catalysts holds significant promise for tailoring the weight of each reaction pathway by promoting asymmetric adsorption of CO2 molecules at the bimetallic interfaces, thereby effectively modulating the distribution of products.

This research underscores the significant potential of plasma catalysis as an emerging electrification technology for sustainable CO2 conversion and fuel production. The ability to perform these reactions at ambient conditions using a modular and scalable plasma system presents an attractive alternative for the chemical industry.

Furthermore, plasma-based systems can be powered by intermittent renewable electricity, enhancing the feasibility of decentralized fuel and chemical production.

This pioneering work is a major step forward in the field of catalytic CO2 conversion and offers promising avenues for future research and industrial applications to meet the challenge of a sustainable future.

The University of Liverpool research team is a leader in plasma catalysis and has also made pioneering advances in plasma catalytic conversion of CO2 to other fuels and chemicals. For example, they have developed promising plasma processes for CO2 methanation and single-step biogas conversion to methanol and have filed three PCT patents in this area.

Plasma-Catalytic CO2 Hydrogenation to Methanol Using Bimetallic Ni-Co Catalysts at Ambient Conditions, Chem 2024 (Open Access) https://doi.org/10.1016/j.chempr.2024.06.022  

 

 

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Journal

Chem

DOI

10.1016/j.chempr.2024.06.022 

Article Title

Plasma-Catalytic CO2 Hydrogenation to Methanol Using Bimetallic Ni-Co Catalysts at Ambient Conditions

Unlocking the potential of rapeseed: CRISPR edits for hybrid efficiency

GEE I THOUGHT MONSANTO (C) (R) (TD) CANOLA WAS ALREADY GMO

Nanjing Agricultural University The Academy of Science

 

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Phenotypic characterization of flower buds, open flowers, and silique development in WT and four mutants. A The growth and flowering of the WT and four mutants. Blue arrows indicate normally developed flower buds and opening flowers, while white arrows highlight abnormally developed flower buds and flowers. Scale bar = 5 cm. B Flower buds, buds without sepals and petals, and anthers in flower buds before flowering. Scale bar = 0.5 cm; dashed box scale bar = 0.25 cm. C Open flowers without sepals and petals, and anthers in fully opened flowers. Scale bar = 0.5 cm; dashed box scale bar = 0.25 cm. D Siliques at 12 DAP of WT and the four mutants. Scale bar = 2 cm. E, F Paraffin sections of transverse anther in flower buds 1–2 days before flowering in WT (E) and DM (L1) (F). Epidermis (ep), endothecium (en), stomium (st), connective (c), vascular bundle (v), and pollen grains (p). Scale bar = 1 mm. G Pollen viability of WT, L1, L2, L3, and L4 assessed after 5 h of room temperature staining with Alexander’s staining solution. Values in the bars represent means of three biological replicates, and error bars indicate standard deviations. Different lowercase letters above the bars indicate statistical significance at P < 0.05 based on Student’s t-test.

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Credit: Horticulture Research

In a transformative advance for agriculture, scientists have utilized CRISPR/Cas9 technology to develop a male-sterile line in rapeseed. This innovation simplifies the hybrid seed production process, overcoming traditional limitations and enhancing the crop's yield and sustainability. By targeting the BnDAD1 gene, the study disrupts the jasmonic acid pathway, essential for pollen development, leading to a controlled and efficient method for creating hybrids that can significantly boost vegetable oil output to meet global demands.

Hybrid production in rapeseed faces several significant challenges, primarily due to the complexities and limitations of current male sterility systems. Traditional methods often involve intricate management processes and are highly sensitive to environmental conditions, resulting in unstable and inefficient hybrid seed production. Due to these issues, there is a pressing need for a more efficient, stable, and environmentally resilient system to improve hybrid production in rapeseed, ensuring higher yields and better adaptability to varying agricultural conditions.

Researchers from Zhejiang University and Jiaxing Academy of Agricultural Sciences, publishing (DOI: 10.1093/hr/uhae139) in Horticulture Research on May 28, 2024, developed a novel approach using CRISPR/Cas9 technology. This method targets the BnDAD1 gene, creating male-sterile lines in rapeseed, thus simplifying hybrid seed production.

The study effectively disrupted the BnDAD1 gene, which plays a crucial role in the jasmonic acid biosynthesis pathway, using CRISPR/Cas9 technology. This disruption resulted in male sterility due to defects in anther dehiscence and pollen maturation in rapeseed. By applying exogenous methyl jasmonate, the researchers were able to restore fertility in the male-sterile lines, enabling the production of F1 hybrid seeds. This new two-line system offers a more straightforward and efficient method for hybrid seed production compared to traditional systems, which often face environmental stability issues. The male sterility induced by the CRISPR/Cas9 method proved to be stable and complete, independent of environmental conditions, making it a robust solution for hybrid rapeseed production. This innovative approach holds significant commercial potential, promising to enhance the efficiency and sustainability of rapeseed cultivation.

Dr. Lixi Jiang, lead researcher from Zhejiang University, stated, "Our findings present a significant advancement in rapeseed hybrid production. The use of CRISPR/Cas9 to induce male sterility simplifies the breeding process and holds great promise for enhancing rapeseed yield and sustainability."

This innovative approach can revolutionize hybrid seed production in rapeseed, providing a more efficient and stable method. The application of this technology can lead to increased yields and sustainability in rapeseed cultivation, addressing the growing global demand for vegetable oil.

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References

DOI

10.1093/hr/uhae139

Original Source URL

https://doi.org/10.1093/hr/uhae139

Funding information

This work was sponsored by the STI 2030 – Major Projects (2023ZD04008).

About Horticulture Research

Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.

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Journal

Horticulture Research

DOI

10.1093/hr/uhae139 

Subject of Research

Not applicable

Article Title

A CRISPR/Cas9-induced male-sterile line facilitating easy hybrid production in polyploid rapeseed (Brassica napus)

 

How farmers and tech teamed up to better test crops

The Alliance of Bioversity International and the International Center for Tropical Agriculture

 

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The tricot approach enables farmers to test new crop varieties and improve food security in their communities.

 

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Credit: Ammaly Phengvilaysouk / CGIAR initiative on Mixed Farming Systems

For over a decade, farmers across the world have been working hand-in-hand with researchers at the Alliance of Bioversity International and CIAT and their collaborators to develop a better way to test new crop varieties and improve food security in their communities.

Food insecurity is on the rise worldwide, with 345 million people in 82 countries suffering acute food insecurity in 2022; making it more important than even to test and roll-out new crop varieties adapted to changing local conditions and in keeping with local needs and capabilities.  

But it wasn’t always so easy to get farmers and agricultural researchers on the same page: not so long ago, most crop varieties and other technologies were tested in large-scale field plots under generic conditions. This meant there was little attention paid to how weather conditions affected crop yield and there was also little interest or buy-in from farmers. 

Jacob van Etten, Principal Scientist and Director for Digital Inclusion, explains that tricot, (an abbreviation for triadic comparison of technologies) was originally developed to create a more cooperative “citizen science” focus, allowing new crop varieties to be tested directly in farmers’ fields, in the same context where they will hopefully be grown after the study.

“It’s the interaction between people and technology that drives innovation,” he says, “We are still doing methodological research on how we can design trials in a way that farmers can get out of it that they want to get out of it.”

From Citizen Science to Farm Collaborators

Brazilian scientist Kauê de Sousa, a researcher at the Alliance of Bioversity International and CIAT started working with tricot back in 2016, as a data analyst for the first set of data generated in India. 

“Tricot helped to put the farmers’ fields at the center of the agricultural experimentation: unlike previous approaches, farmers’ don’t evaluate or comment in someone else plot, but in their own small plot,” de Sousa says, “This increases collaboration and makes the communication more interesting, not only to farmers and researchers, but to the whole community.” 

A 2024 study involved hundreds of common bean smallholder farmers from 140 villages in the Trifinio region of El Salvador, Guatemala, and Honduras, evaluated tricot; a group-based participatory variety testing approach and a control approach to evaluate the effectiveness of the different approaches. 

The study’s first author, Martina Occelli, explains that the researchers found that national programs can benefit from the cost-effective, equitable, externally valid, and scalable nature of citizen science on-farm testing approach for the goal of informing breeding programs.

“A citizen science on-farm testing approach should be used for on-farm testing and a group-based agronomy training could be delivered separately, for example to farmers who have gone through one round of citizen science on-farm testing,” she says adding that a hybrid approach would lead to fewer farmers dropping out of the trial and increase data value. 

“It would also benefit farmers through a group-based training approach,” she says.

Watch the video: https://youtu.be/GtoxXBwyrUU 

Emerging benefits from farmer-driven research 

Van Etten explains that tricot is now mature enough to start thinking about how researchers can organize farmer networks in a way that can scale and build up experience and be more famer-focused. 

“We are still doing methodological research on how we can design trials in a way that farmers can get out of it what they want to,” van Etten says, adding that if research is more farmer-driven, they can help guide the technological direction of agronomical research.

“It doesn't mean that it's an adversarial idea, it's about how to put different innovations side by side with farmers.”

Another 2024 paper, “The tricot approach: an agile framework for decentralized on-farm testing supported by citizen science. A retrospective” de Sousa, van Etten and their co-authors explained that there are still key issues to resolve, from how to sustain enthusiasm, skills and financing among the scientific, technical, and farmer communities; to making tricot participants become more representative of the gender and other socio-economic diversity found in farming communities. 

As more researchers and private extension networks start to use tricot around the world, more benefits from involving farmers are emerging. 

A July 2024 study from Uganda showed that applying the tricot methodology allowed researchers to factor in not only the crop-specific information, but also the culinary preferences (like taste and cookability) of the farmers. The same researchers also explored the role of gender in crop preferences. 

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A farmer checks plants in her plot in Laos. 

Credit: Ammaly Phengvilaysouk / CGIAR initiative on Mixed Farming Systems

Journal

Crop Science

DOI

10.1002/csc2.21293 

Article Title

On-farm evaluation of cassava clones using the triadic comparison of technology options approach

 

Spectral measurements capable of estimating nutrient content of forest tree leaves

Journal of Remote Sensing

The general health of forests can be estimated by the micro- and macronutrient content of tree leaves to help inform forest management decisions in the light of climate change, species loss and other variables. Traditional methods of assessing nutrient levels in forests are expensive and labor-intensive. Researchers recently analyzed the reflected spectra from tree foliage to accurately estimate the nutrients of leaves, offering a faster, larger-scale method of assessing forest health.

 

Field methods of collecting leaf samples and then measuring foliage nutrient content in the lab are time-consuming. New, faster methods are required to estimate forest health as climate change alters growing conditions. To address this issue, a team of researchers from the University of Massachusetts and the University of Virginia analyzed reflected light (spectra) across a wide range of wavelengths from forest foliage to accurately determine the concentrations of calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), manganese (Mn), and zinc (Zn) in leaves.

 

The team published the study on June 27 in the Journal of Remote Sensing.

 

Specifically, the researchers measured reflected light at wavelengths from 400 to 2,450 nanometers (nm, 1.0 x 10-9 m) to assess nutrient concentrations. The team was able to identify the best wavelengths to measure each nutrient analyzed through a partial least squares regression (PLSR). PLSR is especially well-suited to manage highly correlated independent variables, like the individual reflectence over a continuous spectrum.

 

“The developed PLSR model predicted plant nutrients with moderate to strong accuracy for macro- and micronutrients in temperate hardwood forests of the Northeastern United States. Spectral measurements combined with wavelength selection and PLSR models can be used to quantify foliar macro- and micronutrients at regional scales and can be further improved by incorporating site geologic materials and tree genera,” said Qian Yu, associate professor in Earth, Geographic, and Climate Sciences at the University of Massachusetts-Amherst and the corresponding author of the research paper.

 

The researchers realized that their ability to accurately use spectra to determine the nutrient level of tree foliage could be significantly improved by considering the soil type in which the trees grew in. Notably, this variable is often overlooked when assessing the nutrient composition of tree leaves. The team measured the foliage nutrients Ca and P of trees in four types of soil: coarse glacial till, glaciofluvial, melt-out till and outwash. By accounting for soil type, researchers improved their PLSR nutrient analysis accuracy from R2 = 0.66 to R2 = 0.87 (an R2, or coefficient of determination, that equals 1.0 indicates that all variation observed is due to differences in the independent variable, or spectral measurements).

 

Different soils had greater and lesser effects on Ca and P. Soil had little effect on Ca concentrations, for example, but tended to affect P to a greater degree. Outwash soil also provided the most accurate predictions for both Ca and P nutrients. Critically, Ca is a limiting nutrient in forests that plays important roles in plant structure, chemical signaling and as an enzyme cofactor that changes enzyme efficiency.

 

The genus of the trees additionally affected the accuracy of foliage nutrient concentration predictions. In fact, analyzing spectral data based on tree genera improved the accuracy of nutrient predictions even better than soil composition. Tree genus improved Ca prediction accuracy from R2 = 0.66 to as high as R2 = 0.91 and R2 = 0.93 for Fagus (Beech) and Quercus (Oak) genera, respectively. The team analyzed spectral data for Acer (Maple) and Betula (Birch) genera as well.

 

The research team suggests that specific tree genera likely influence foliage nutrients because the physiological mechanisms responsible for nutrient acquisition and transport are genetically controlled and unique to each genus. Additionally, some tree genera may require individual nutrients more than other genera that may be more adapted to a particular soil, resulting in differences in nutrient uptake.

 

Ultimately, the research team is hopeful that their new spectral assessment technique will be successfully applied to other hardwood forests to inform important forest management decisions. “The method introduced in this paper holds promise for large-scale plant nutrient assessment and can decrease the costs of traditional, field-based approaches,” said Wenxiu Teng, Ph.D. candidate in Earth, Geographic, and Climate Sciences at the University of Massachusetts-Amherst and first author of the paper.

 

Other contributors to this research include Justin B. Richardson and Alexandrea M. Rice from the Department of Environmental Sciences at the University of Virginia in Charlottesville and Ivan C. Mischenko from the Department of Earth, Geographic, and Climate Sciences at the University of Massachusetts in Amherst and.

 

This research was supported by the University of Massachusetts Amherst, College of Natural Sciences by Award 1801.

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Journal

Journal of Remote Sensing

DOI

10.34133/remotesensing.0093 

Article Title

Predicting Foliar Nutrient Concentrations across Geologic Materials and Tree Genera in the Northeastern United States Using Spectral Reflectance and Partial Least Squares Regression Models

 

High nitrogen input promotes the redistribution of new organic carbon to deeper soil layers

Higher Education Press

 

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Fig 1

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Credit: Hualing HU, Liang ZHAO, Wenbing TAN , Guoan WANG, Beidou XI

Exogenous reactive nitrogen input has a profound effect on the carbon cycle of terrestrial ecosystems. Most current research on soil organic carbon (SOC) dynamics in relation to nitrogen input has focused predominantly on the surface soil layers. However, studies limited to the surface layer cannot fully reveal the complete response of SOC to nitrogen input because approximately half of the SOC is stored in deeper soil layers. Given the unique environmental conditions of deep soils, microbial decomposition and stabilization of deep SOC may respond differently compared to surface soils. Moreover, surface-only studies have not addressed whether nitrogen input affects the vertical migration of SOC, thereby influencing the distribution of newly absorbed carbon throughout the entire soil profile. Consequently, conducting whole-profile soil studies is essential for accurately predicting SOC exchange with the atmosphere in response to nitrogen input.

A research team led by Dr. Wenbing Tan from the Chinese Research Academy of Environmental Sciences conducted a long-term field experiment at an agricultural site, collecting soil samples from plots with varying nitrogen fertilizer treatments. By analyzing stable carbon isotopes, the team investigated the contributions of new versus old carbon to SOC and aimed to elucidate the role of soil depth in this context. Additionally, the team integrated physical and chemical soil properties with the vertical distribution of organic carbon and nitrogen to explore the mechanisms of SOC dynamics in response to different rates of nitrogen fertilizer application in deep soils.

The study revealed that SOC increased significantly with nitrogen fertilizer application, with the extent of this increase depending on the amount of nitrogen applied. Compared to low nitrogen fertilizer addition, high nitrogen fertilizer application significantly enhanced SOC sequestration primarily through reduced tillage and the return of crop residues to the field. The study observed notable differences in SOC turnover rates under different nitrogen levels. Under low nitrogen conditions, the SOC turnover time in the 0–20 cm soil layer was approximately 20–40 years, whereas under high nitrogen conditions, the SOC turnover time in the 10–20 cm soil layer extended up to 100 years. High nitrogen fertilizer application mainly increased SOC sequestration by transferring organic matter from the surface to more stable deep soil layers. Due to the high turnover rate of new organic carbon in deep soils under low nitrogen conditions, the carbon sequestration capacity of SOC in deep soils was less compared to that under high nitrogen conditions.

The results support the notion that reduced microbial decomposition rates of SOC under high nitrogen input conditions are a key mechanism for enhancing soil carbon sink functions. More importantly, the research team confirmed that the increased soil carbon sink strength under high nitrogen enrichment conditions is primarily due to enhanced vertical transport of soil organic matter, leading to a greater distribution of new organic carbon in deeper soil layers. This new mechanism offers a significant explanation for the enhancement of soil carbon storage. Future research should further define the exact impact range of this new mechanism under different nitrogen application levels and explore the applicability of these findings across various terrestrial ecosystems.

This study has been published on the Journal of Frontiers of Agricultural Science and Engineering on 2024, Vol. 11, No. 2. DOI: 10.15302/J-FASE-2024565.

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Journal

Frontiers of Agricultural Science and Engineering

DOI

10.15302/J-FASE-2024565 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Discrepant responses of soil organic carbon dynamics to nitrogen addition in different layers: a case study in an agroecosystem