Soil moisture variations affect short-term plant-microbial competition for ammonium, glycine, and glutamate.

Katarina Månsson, Magnus Olsson, Ursula Falkengren-Grerup, Göran Bengtsson

Research output: Contribution to journalArticlepeer-review

13 Citations (SciVal)

Abstract

We tested whether the presence of plant roots would impair the uptake of ammonium ([Formula: see text]), glycine, and glutamate by microorganisms in a deciduous forest soil exposed to constant or variable moisture in a short-term (24-h) experiment. The uptake of (15)NH4 and dual labeled amino acids by the grass Festuca gigantea L. and soil microorganisms was determined in planted and unplanted soils maintained at 60% WHC (water holding capacity) or subject to drying and rewetting. The experiment used a design by which competition was tested in soils that were primed by plant roots to the same extent in the planted and unplanted treatments. Festuca gigantea had no effect on microbial N uptake in the constant moist soil, but its presence doubled the microbial [Formula: see text] uptake in the dried and rewetted soil compared with the constant moist. The drying and rewetting reduced by half or more the [Formula: see text] uptake by F. gigantea, despite more than 60% increase in the soil concentration of [Formula: see text]. At the same time, the amino acid and [Formula: see text]-N became equally valued in the plant uptake, suggesting that plants used amino acids to compensate for the lower [Formula: see text] acquisition. Our results demonstrate the flexibility in plant-microbial use of different N sources in response to soil moisture fluctuations and emphasize the importance of including transient soil conditions in experiments on resource competition between plants and soil microorganisms. Competition between plants and microorganisms for N is demonstrated by a combination of removal of one of the potential competitors, the plant, and subsequent observations of the uptake of N in the organisms in soils that differ only in the physical presence and absence of the plant during a short assay. Those conditions are necessary to unequivocally test for competition.
Original languageEnglish
Pages (from-to)1061-1072
JournalEcology and Evolution
Volume4
Issue number7
DOIs
Publication statusPublished - 2014

Bibliographical note

The information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Biodiversity (432112235), Plant Ecology and Systematics (Closed 2011) (011004000)

Subject classification (UKÄ)

  • Ecology

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