Seasonal changes in the abundance and activity of bacterial and fungal denitrifying communities associated with different compost amendments.

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From: Canadian Journal of Microbiology(Vol. 68, Issue 2)
Publisher: NRC Research Press
Document Type: Report
Length: 8,310 words
Lexile Measure: 1510L

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Abstract :

Composts can be efficient organic amendments in potato culture as they can supply carbon and nutrients to the soil. However, more information is required on the effects of composts on denitrification and nitrous oxide emissions ([N.sub.2]O) and emission-producing denitrifying communities. The effects of three compost amendments (municipal source separated organic waste compost (SSOC), forestry waste mixed with poultry manure compost (FPMC), and forestry residues compost (FRC)) on fungal and bacterial denitrifying communities and activity was examined in an agricultural field cropped to potatoes during the fall, spring, and summer seasons. The denitrification enzyme activity (DEA), [N.sub.2]O emissions, and respiration were measured in parallel. [N.sub.2]O emission rates were greater in FRC-amended soils in the fall and summer, whereas soil respiration was highest in the SSOC-amended soil in the fall. A large number of nirK denitrifying fungal transcripts were detected in the fall, coinciding with compost application, while the greatest nirK bacterial transcripts were measured in the summer when plants were actively growing. Denitrifying community and transcript levels were poor predictors of DEA, [N.sub.2]O emissions, or respiration rates in compost-amended soil. Overall, the sampling date was driving the population and activity levels of the three denitrifying communities under study. Key words: denitrification, gene expression, nirS denitrifying bacteria, nirK denitrifying bacteria, nirK denitrifying fungi, primers. Les composts peuvent constituer des amendements organiques efficaces dans la culture de la pomme de terre, car ils peuvent fournir du carbone et des nutriments au sol. Cependant, il est necessaire d'obtenir davantage d'information sur les effets des composts sur la denitrification et les emissions d'oxyde nitreux ([N.sub.2]O) et sur les communautes denitrifiantes productrices des emissions. L'effet de trois amendements de compost (compost de dechets organiques municipaux separes a la source (COSS), compost de dechets forestiers melanges a du fumier de volaille (CFFV) et compost de residus forestiers (CRF) sur les communautes et l'activite de denitrification fongiques et bacteriennes a ete examine dans un champ agricole cultive en pommes de terre pendant les saisons d'automne, de printemps et d'ete. L'activite enzymatique de denitrification (AED), les emissions de [N.sub.2]O et la respiration ont ete mesurees en parallele. Les taux d'emission de [N.sub.2]O etaient plus eleves dans les sols amendes au CRF en automne et en ete, tandis que la respiration du sol etait la plus elevee dans les sols amendes au COSS en automne. Un grand nombre de transcrits fongiques denitrifiants nirK a ete detecte a l'automne, corncidant avec l'application du compost, tandis que le nombre le plus eleve de transcrits bacteriens nirK a ete mesure en ete, lorsque les plantes etaient en pleine croissance. La communaute denitrifiante et les niveaux de transcrits etaient de mauvais predicteurs de l'AED, des emissions de [N.sub.2]O ou des taux de respiration dans le sol amende au compost. Dans l'ensemble, la date d'echantillonnage determinait les niveaux de population et d'activite des trois communautes denitrifiantes etudiees. Mots-cles : denitrification, expression genetique, bacteries denitrifiantes nirS, bacteries denitrifiantes nirK, champignons denitrifiants nirK, amorces.

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Gale Document Number: GALE|A693514954