Journal ArticleDOI
Sugars in soil and sweets for microorganisms: Review of origin, content, composition and fate
Anna Gunina,Yakov Kuzyakov +1 more
Abstract:
Sugars are the most abundant organic compounds in the biosphere because they are monomers of all polysaccharides. We summarize the results of the last 40 years on the sources, content, composition and fate of sugars in soil and discuss their main functions. We especially focus on sugar uptake, utilization and recycling by microorganisms as this is by far the dominating process of sugar transformation in soil compared to sorption, leaching or plant uptake. Moreover, sugars are the most important carbon (C) and energy source for soil microorganisms. Two databases have been created. The 1st database focused on the contents of cellulose, non-cellulose, hot-water and cold-water extractable sugars in soils (348 data, 32 studies). This enabled determining the primary (plant-derived) and secondary (microbially and soil organic matter (SOM) derived) sources of carbohydrates in soil based on the galactose + mannose/arabinose + xylose (GM/AX) ratio. The 2nd database focused on the fate of sugar C in soils (734 data pairs, 32 studies using 13 C or 14 C labeled sugars). 13 C and 14 C dynamics enabled calculating the: 1) initial rate of sugar mineralization, 2) mean residence time (MRT) of C of the applied sugars, and 3) MRT of sugar C incorporated into 3a) microbial biomass and 3b) SOM. The content of hexoses was 3–4 times higher than pentoses, because hexoses originate from plants and microorganisms. The GM/AX ratio of non-cellulose sugars revealed a lower contribution of hexoses in cropland and grassland (ratio 0.7–1) compare to forest (ratio 1.5) soils. 13 C and 14 C studies showed very high initial rate of glucose mineralization (1.1% min −1 ) and much higher rate of sugars uptake by microorganisms from the soil solution. Considering this rate along with the glucose input from plants and its content in soil solution, we estimate that only about 20% of all sugars in soil originate from the primary source – decomposition of plant litter and rhizodeposits. The remaining 80% originates from the secondary source – microorganisms and their residues. The estimated MRT of sugar C in microbial biomass was about 230 days, showing intense and efficient internal recycling within microorganisms. The assessed MRT of sugar C in SOM was about 360 days, reflecting the considerable accumulation of sugar C in microbial residues and its comparatively slow external recycling. The very rapid uptake of sugars by microorganisms and intensive recycling clearly demonstrate the importance of sugars for microbes in soil. We speculate that the most important functions of sugars in soil are to maintain and stimulate microbial activities in the rhizosphere and detritusphere leading to mobilization of nutrients by accelerated SOM decomposition – priming effects. We conclude that the actual contribution of sugar C (not only whole sugar molecules, which are usually determined) to SOM is much higher than the 10 ± 5% commonly measured based on their content.read more
Citations
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Journal ArticleDOI
Rhizosphere size and shape: Temporal dynamics and spatial stationarity
TL;DR: In this article, a literature analysis allows the conclusion that the rhizosphere extent for most of the parameters assessed by non-destructive visualization techniques is 0.5-4 cm, but exceeds 4 cm for gases, nitrate, water and redox potential.
Journal ArticleDOI
Plant- or microbial-derived? A review on the molecular composition of stabilized soil organic matter
TL;DR: In this paper, the authors synthesize data on the contribution of plant and microbial-derived compounds to stabilized SOM, i.e., aggregates and mineral-associated organic matter (MAOM), and review the role of environmental factors influencing this contribution.
Journal ArticleDOI
Plant-derived coumarins shape the composition of an Arabidopsis synthetic root microbiome.
TL;DR: It is found that lack of coumarin biosynthesis in f6′h1 mutant plant lines causes a shift in the root microbial community specifically under iron deficiency, and a potential role for iron-mobilizing coumarins is demonstrated in sculpting the A. thaliana root bacterial community by inhibiting the proliferation of a relatively abundant Pseudomonas species via a redox-mediated mechanism.
Journal ArticleDOI
Plant health: feedback effect of root exudates-rhizobiome interactions.
Oluwaseyi Samuel Olanrewaju,Ayansina Segun Ayangbenro,Bernard R. Glick,Olubukola Oluranti Babalola +3 more
TL;DR: To optimize the growth and productivity of host plants, rhizobiome microbial diversity and modulatory techniques need to be clearly understood for improved plant health.
Journal ArticleDOI
Carbon and nitrogen recycling from microbial necromass to cope with C:N stoichiometric imbalance by priming
Jun Cui,Zhenke Zhu,Xingliang Xu,Shoulong Liu,Davey L. Jones,Yakov Kuzyakov,Olga Shibistova,Jinshui Wu,Tida Ge +8 more
TL;DR: In this paper, the impact of increasing amounts of labile C input on priming effects (PE) on soil organic matter (SOM) mineralization remains unclear, particularly under anoxic conditions and under high C input common in microbial hotspots.
References
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Journal ArticleDOI
Analysis of factors controlling soil organic matter levels in Great Plains grasslands
TL;DR: In this article, a model of soil organic matter (SOM) quantity and composition was used to simulate steady-state organic matter levels for 24 grassland locations in the U.S. Great Plains.
Journal ArticleDOI
Organic acids in the rhizosphere: a critical review
TL;DR: In this article, a review of the role of organic acids in rhizosphere processes is presented, which includes information on organic acid levels in plants (concentrations, compartmentalisation, spatial aspects, synthesis), plant efflux (passive versus active transport, theoretical versus experimental considerations), soil reactions (soil solution concentrations, sorption) and microbial considerations (mineralization).
Journal ArticleDOI
Stabilization of organic matter in temperate soils: mechanisms and their relevance under different soil conditions – a review
Margit von Lützow,Ingrid Kögel-Knabner,Klemens Ekschmitt,Egbert Matzner,Georg Guggenberger,Bernd Marschner,Heinz Flessa +6 more
TL;DR: In this article, a review of the mechanisms that are currently, but often contradictorily or inconsistently, considered to contribute to organic matter (OM) protection against decomposition in temperate soils is presented.
Book ChapterDOI
Soil organic matter and structural stability: mechanisms and implications for management
TL;DR: In this paper, two categories of aggregates macro- (> 250 μm) and micro- (< 250μm) depend on organic matter for stability against disruptive forces caused by rapid wetting.
Journal ArticleDOI
The macromolecular organic composition of plant and microbial residues as inputs to soil organic matter
TL;DR: In this paper, an overview is given on the amount of litter input, the proportion of various plant parts and their distribution (below-ground/above-ground), as well as the relative proportion of different plant tissues.