The Project

This project has received funding from the European Union’s Horizon 2021-2027 research and innovation programme under grant agreement No 101079299.

ACTIONr

RESEARCH ACTION NETWORK FOR REDUCING REACTIVE NITROGEN LOSSES FROM AGRICULTURAL ECOSYSTEMS

ACTIONr is EU-funded project under the HORIZON-WIDERA-2021-ACCESS-03 funding scheme that aims to unravel the scientific excellence and innovation potential of the University of Thessaly by establishing new tools and pathways to optimise nitrogen use efficiency, decelerate the N cycle, and decrease the environmental footprint of Nr. To achieve this, UTH will twin with two internationally leading partners in the ecogenomics (University of Vienna) and microbial ecology (École Centrale de Lyon) of the soil N cycle.

Budget: 1,480,300 million €
Starting date: 1st November 2022

Duration: 36 months

Globally, 50-70% of the N fertilizer applied to cropping systems is lost as nitrate and N-oxides, raising agricultural production costs and contributing to environmental pollution and climate change. These losses are directly linked to the nitrification process catalysed by soil nitrifying microbes. The mitigation of reactive nitrogen (Nr) loss via nitrification inhibitors (NIs) is a promising solution for increasing N use efficiency (NUE) in agriculture. ACTIONr aims to unravel the scientific excellence and innovation potential of a Widening country (Greece), through a European network of excellence on establishing novel tools and pathways for optimized NUE, reducing the continued acceleration of the N cycle, and decreasing the environmental footprint of Nr. As a centre for Greek agricultural production, Thessaly is suited to serve as a model for research on microbial N transformations for optimizing NUE in agroecosystems, but local capacity is not fully explored yet. Twinning of UTH with two internationally leading partners in Ecogenomics (UNIVIE) and Microbial Ecology (ECL) of the soil N cycle will: (i) further develop research excellence of UTH, (ii) improve its networking efficiency and interdisciplinarity, and (iii) have broad societal and environmental impact towards more efficient N management in agricultural settings. These objectives will be achieved through the implementation of a well-designed plan of training, networking, and dissemination/communication activities, including staff exchanges, on-site training, summer schools and symposia, working groups on protocol unification, integrated PhD programs, and outreach events directed towards potential stakeholders and local communities. The expected impacts include an increase in scientific output and capacity building of UTH, the integration of sustainable N-fertilization strategies at EU level in compliance with SDG (e.g., SDG13 and 15), and the stimulation of public awareness on agri-environmental issues.

Context

Nitrogen (N) is an essential nutrient for all living beings (microorganisms, plants, and animals) and the most abundant element in Earth’s atmosphere where it mainly occurs as dinitrogen gas (N2). Although there is a lot of N2 around us (∼78% of the air we breathe), plants or animals cannot directly use this chemically unreactive form without first been transformed or “fixed” into reactive nitrogen (Nr) containing compounds such as ammonia (NH3) or N oxides. N2 can be naturally converted into N containing compounds through lightning strikes or by specialized Ν-fixing microorganisms either free-living in the soil or attached to the roots of certain plants like beans or clover. However, the supply of naturally fixed N in most natural ecosystems and in farmlands is low, often limiting ecosystem productivity. The early 1900’s invention of the Haber-Bosch process for the production of synthetic ammonium-based fertilizers has doubled Nr input into the World’s soils and enabled us to nutritionally sustain the global population increase of the 20th century. While the application of synthetic fertilizers is currently indirectly feeding 50% of humanity, it has also, accelerated the global N cycle. Critically, the low N fertilizer use efficiency (NUE) in agriculture, a measure of N retained in food per amount of N fertilizer applied, leads to massive N fertilizer losses (50–70%) to the environment, as NH3, nitrate (NO3), and nitrous oxide (N2O), a greenhouse gas (GHG) with a warming potential ∼300 times greater than carbon dioxide. These losses are connected to pernicious environmental issues that we currently face such as biodiversity loss, eutrophication of aquatic ecosystems, ozone and air quality degradation, and GHG-driven climate change. Beyond its environmental impact, Nr pollution costs to EU up to €320 billion per year, double the value that N fertilizers are estimated to add to European farm income.

Nr losses from fertilized soils are directly linked to the microbially mediated process of nitrification, which generates the soil-mobile anion NO3 from relatively immobile ammonium (NH4+) pools, causing significant losses of Nr from agricultural systems via NO3leaching, and providing substrates to specialized soil microorganisms (both nitrifying and denitrifying microorganisms) to produce N2O. In N-limited soils, nitrification rates are typically low, but in fertilized soils, about 90% of N flows through the nitrification pathway. These make the nitrification process and the associated microbial players an appealing inhibition target to minimize N loss from agricultural soils.

Three types of microorganisms, including ammonia-oxidizing bacteria and archaea, and the recently discovered complete ammonia-oxidizing (comammox) bacteria can perform the first step of nitrification, the oxidation of NH3 to NO2. All three groups of ammonia oxidizers (AOM) utilize NH3 as their main energy source, through a reaction catalysed by ammonia monooxygenase (AMOs) enzymes. Apart from being necessary for the activity of all aerobic AOM, AMOs have a broad substrate range and mediate the initial and often rate- limiting step of nitrification. Thus, AMOs are generally considered as an ideal target for the suppression of the overall nitrification process.

Today, the direct inhibition of soil AOM using synthetic nitrification inhibitors (SNIs) along with N fertilizers, is a well-established strategy for improving NUE. However, while the underlying inhibition mechanisms of all currently used in agriculture NIs have been associated with the inactivation of AMO, their efficacy in regulating soil N transformations is highly variable across soils and often suboptimal due to the variable sensitivity of soil AOM to different NIs, the dependency of NIs performance on the composition of the metabolically active AOM community in soil and the lack of knowledge on the actual biochemical mode of action of NIs which prohibit any prediction on their activity against the different groups of AOM in soil.

In addition to SNIs, functionally similar plant derived compounds that inhibit nitrification, called biological nitrification inhibitors (BNIs), have recently received increased attention as safer alternatives to SNIs. However, the potential of BNIs to inhibiting nitrification is still unknown. Previous research has shown that BNIs in crop root exudates can suppress up to 90% of nitrification activity in soil and increase soil N retention, providing plants with a competitive advantage for N fertilizer. However, before BNIs can be applied in agricultural practices it is necessary to acquire a deeper understanding of their effect on N cycling, as well as on the overall soil microbiome integrity, plant health and nutrition.

Overall objectives

The main research focus of the EU-funded ACTIONr project will be the investigation of the complex interactions of NIs with N cycling microbial players at different experimental scales, from in vitro assays with single organisms, to synthetic microbial communities of nitrifiers and eventually to natural soil microbial assemblages, with ultimate goal to establish new tools and pathways to optimise NUE, decelerate the N cycle, and decrease the environmental footprint of Nr. To this end, ACTIONr has defined a series of specific research objectives as follows: a) to identify the mode of action of NIs at cellular level which remains unknown despite the long-standing presence of NIs in the agricultural market; (b) to develop and use synthetic microbial communities of nitrifiers as an ecologically relevant tool for NI activity screening; (c) to develop experimental tools to assess the activity and effects of NIs on AOM and off target microorganisms participating or not in N cycling and to address the reciprocal effects on GHG emissions; (d) to gather all experimental data in support of the development and validation of novel, safer and more efficient NIs.

Twinning of UTH with UNIVIE and ECL aims to (i) unravel the scientific excellence and innovation potential of UTH in the field of microbial ecology, ecophysiology, and ecogenomics of the soil N cycle, (ii) further develop its scientific output and capacity building, (ii) improve its networking efficiency and interdisciplinarity, and (iii) have broad societal, environmental, and financial impact towards more efficient N management in agricultural settings. These objectives will be achieved through the implementation of a well-designed plan of training, technology transfer, networking, and dissemination, communication and exploitation (DEC) activities, including: bi-directional staff exchanges, on-site training, summer schools, thematic workshops and symposia on nitrification and related processes, networking fora on protocols and tools standardization, integrated PhD programs, and a diverse set of DEC measures directed towards the scientific community, potential stakeholders, and local communities.

Expected Impacts

The major expected impacts of ACTIONr include (i) the improvement of our understanding on the impact of synthetic and biological NIs on soil microbial N transformation networks and to their contribution to fertilizer loss and GHG emissions in terrestrial ecosystems; (ii) the increase of agronomic and economic value of N fertilizers along with (iii) the amplification of innovation potential and market competitiveness of the agrochemical industrial sector in Greece, (iv) the integration of sustainable N-fertilization strategies at EU level in compliance with SDG (e.g., SDG13 and 15) towards lowering the  environmental footprint of Nr; and (v) the stimulation of public awareness on the effective and sustainable Nr use.