{"id":4795,"date":"2026-07-12T11:35:04","date_gmt":"2026-07-12T11:35:04","guid":{"rendered":"https:\/\/eucface.hieresearch.org\/?page_id=4795"},"modified":"2026-07-27T07:32:53","modified_gmt":"2026-07-27T07:32:53","slug":"microbial-nutrient-cycling","status":"publish","type":"page","link":"https:\/\/eucface.hieresearch.org\/index.php\/microbial-nutrient-cycling\/","title":{"rendered":"Microbial nutrient cycling"},"content":{"rendered":"\t\t
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Microbial nutrient cycling<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Project team:<\/b>\u00a0Manon Rumeau (Universit\u00e9 de Pau et des Pays de l’Adour), Fotis Sgouridis (University of Bristol), Catriona A. Macdonald (Western Sydney University), Paola Pisetta Raupp (Western Sydney University), Charles Warren, (University of Sydney) Michaela K. Reay (University of Bristol), A. Rob MacKenzie (University of Birmingham), Sami Ullah (University of Birmingham) and Yolima Carrillo (Western Sydney University)<\/p>

Project period:<\/b> 2025 – 2026<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tYou can find contacts to the Western Sydney University members of the project here<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Summary<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Our aim was to understand if the soil microbial response to eCO\u2082 is constrained by P limitation, and if P application will shift the system from P to N limitation and how this shifting the limiting nutrient might modify this response of the forest to eCO\u2082. <\/i><\/p>

I studied the interactive effect of P fertilization and eCO\u2082 at EucFACE. I followed soil nutrient, microbial pools, N processes and enzymatic activities right before fertilization and two months after. The experiment was conducted from March to May 2023 in the four first FACE rings. Inside each ring, samples were taken in the soil sampling plots and each sampling plot had a subplot that did not receive fertilization that allowed us to compare unfertilized and fertilized plots in each ring.\u00a0<\/i><\/p>

The detailed analyses are root biomass, gravimetric moisture, N-NH4+, N-NO3-, free amino acids, Bray-P, Dissolved organic C, Dissolved organic N, Microbial biomass C, N and P, Gross N mineralization, Gross N depolymerization and specific compound N depolymerization, Enzymatic activities: \u03b2-1,4-glucosidase (BG), \u03b2-d-cellobiosidase (CB), \u03b1-glucosidase (AG), and \u03b2-xylosidase (Bxyl), \u03b2-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), Phosphatase (Pho). I also completed this dataset with soil ion exchange membranes measuring available NO3, NH4, PO4 during two years before fertilization (March 2023).<\/em><\/p>

Key findings:\u00a0<\/u>We found that P addition decreased extracellular soil enzymatic activities associated with C-N-P-mining (\u2500 50%), increased microbial NH4+ retention (immobilization: mineralization ratio; + 23%) and microbial C use efficiency (CUE; + 12%), causing a reduction in plant-available N (\u2500 30%) independently from eCO\u2082. Under eCO\u2082, P addition stimulated protein depolymerization and C-P enzyme activities. Compound specific analyses revealed increased microbial biosynthesis with P addition via the assimilation of key amino acids such as alanine, glycine and glutamate. These findings indicate that P limitation constrains microbial C-N cycling under eCO\u2082 by diverting microbial C investment toward P acquisition rather than growth. While alleviating P limitation can rapidly stimulate microbial cycling and promotes microbial C retention under eCO\u2082, this response may only be transient, as enhanced microbial growth drives the system towards N limitation.<\/i><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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Publications<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The research project is completed and the paper is now in review in Global Change Biology named: \u201cRelaxing P limitation in a P-limited Eucalyptus forest rapidly enhances microbial C-N cycling under elevated CO\u2082<\/i>\u201d.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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You are welcome to take part in discussions about the research topic below. To start click a desired topic below. To prevent spam we ask you to create an account. You do this by clicking a topic and then hit the Login button. Then an option to create an account will appear.\u00a0<\/span><\/p>

Note that you might get a message from the University spam filter to allow notifications from the forum first time you use it. For WSU “You have new held emails”. Click Permit. <\/span>After that it should not be an issue.\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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