Root Exudates Induce Soil Macroaggregation Facilitated by Fungi in Subsoil

Baumert, Vera; Vasilyeva, Nadezda; Vladimirov, A. A.; Meier, Ina C.; Kögel‐Knabner, Ingrid; Mueller, Carsten W.

doi:10.3389/fenvs.2018.00140

Cited by 148 publications

(90 citation statements)

References 88 publications

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“…Although recent research indicates that increasing root-C inputs can stimulate aggregation in deep soil layers (Baumert et al, 2018), the results of our physical fractionation indicate that integrating alfalfa into a cropping system has little impact on SOC stabilization through microaggregation. At Nashua and Marsden, the distribution of SOC among fractions was quite similar between cropping systems at all depths ( Figs.…”

Section: Values (Supplementarycontrasting

confidence: 80%

Whole-profile soil organic matter content, composition, and stability under cropping systems that differ in belowground inputs

Poffenbarger

Olk

Cambardella

et al. 2020

Agriculture, Ecosystems & Environment

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Subsoils have been identified as a potential carbon sink because they typically have low soil organic carbon (SOC) concentrations and high SOC stability. One proposed strategy to increase SOC stocks is to enhance C inputs to the subsoil by increasing crop rotation diversity with deep-rooted perennial crops. Using three long-term field trials in Iowa (study durations of 60, 35, and 12 years), we examined the effects of contrasting cropping systems [maize (Zea mays L.)-soybean (Glycine max (L.) Merr) (= two-year system) vs. maize-soybean-oat (Avena sativa L.)/alfalfa (Medicago sativa L.)-alfalfa or maize-maize-oat/ alfalfa-alfalfa (= four-year system)] on above-and below-ground C inputs, as well as the content, biochemical composition, and distribution of SOC among physical fractions differing in stability to 90 cm depth. Average annual total C inputs were similar in the two-year and four-year systems, but the proportion of C delivered belowground was 20-35 % greater in the four-year system. Despite the long duration of these studies, the effect of cropping system on SOC content to 90 cm was inconsistent across trials, ranging from −7 % to +16 % in the four-year relative to the two-year system. At the one site where SOC was significantly greater in the four-year system, the effect of cropping system on SOC content was observed in surface and subsoil layers rather than limited to the subsoil (i.e., below 30 cm).Cropping system had minimal effects on biochemical indicators of plant-derived organic matter or on the proportions of SOC in labile particulate organic matter versus stable mineral-associated organic matter. We conclude that adoption of cropping systems with enhanced belowground C inputs may increase total profile SOC, but the effect is minimal and inconsistent; furthermore, it has minor impact on the vertical distribution, biochemical composition, and stability of SOC in Mollisols of the Midwest U.S.Subsoils have been identified as a potential carbon sink because they typically have low soil organic carbon (SOC) concentrations and high SOC stability. One proposed strategy to increase SOC stocks is to enhance C inputs to the subsoil by increasing crop rotation diversity with deep-rooted perennial crops. Using three longterm field trials in Iowa (study durations of 60, 35, and 12 years), we examined the effects of contrasting cropping systems [maize (Zea mays L.)-soybean (Glycine max (L.) Merr) (= two-year system) vs. maize-soybeanoat (Avena sativa L.)/alfalfa (Medicago sativa L.)-alfalfa or maize-maize-oat/alfalfa-alfalfa (= four-year system)] on above-and below-ground C inputs, as well as the content, biochemical composition, and distribution of SOC among physical fractions differing in stability to 90 cm depth. Average annual total C inputs were similar in the two-year and four-year systems, but the proportion of C delivered belowground was 20-35 % greater in the fouryear system. Despite the long duration of these studies, the effect of cropping system on SOC content to 90 cm was inconsistent across trials...

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Section: Values (Supplementarycontrasting

confidence: 80%

Whole-profile soil organic matter content, composition, and stability under cropping systems that differ in belowground inputs

Poffenbarger

Olk

Cambardella

et al. 2020

Agriculture, Ecosystems & Environment

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“…Our results confirmed that microbial variables had greater impact on SOC in > 0.25 mm macro-aggregates under different fertilizations, whereas no significant effect was found in < 0.25 mm micro-aggregates. The total effect of fungi-related indicators contribution was higher than other microbial indices 77 . More in-depth studies are needed to detect fungal reaction and variation resulting from fertilization and should be incorporated in the main causes of microbial approach that affect C stock.…”

Section: Discussionmentioning

confidence: 64%

The Contribution of Microorganisms to Soil Organic Carbon Stock Under Fertilization Varies among Aggregate Size Classes

Liang

et al. 2021

Preprint

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Long term fertilization alters soil microbiological properties and then affects soil organic carbon (SOC) stocks. However, the interrelations of SOC with biological drivers and their relative importance are rarely analyzed quantitatively at aggregate scale. We investigated the contribution of soil microbial biomass, diversity and enzyme activity to C stock in soil aggregate fractions (> 5 mm, 2 − 5 mm, 1 − 2 mm, 0.25 − 1 mm and < 0.25 mm) at topsoil (0–15 cm) from 27-year long term fertilization regime. Compared to CK (no fertilization management), NPS and NPM (inorganic fertilization plus the incorporation of maize straw or composted cow manure) significantly reduced the impact of NP (inorganic fertilizers application alone) on the growth of microbial community, and increased the microbial contribution to C stock. The results showed that microbial variables were significantly correlated with SOC content in > 0.25 mm aggregates rather than in < 0.25 mm aggregates. Fungal variables (fungal, AM biomass, and F/B ratio) and enzyme activities (BXYL and LAP) in > 0.25 mm aggregates explained 21% and 2% on C, respectively. Overall, organic matter (OM) addition could contribute to higher C storage by boosting fungal community and enzyme activity rather than by changing microbial community diversity in macro-aggregates.

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“…The aggregated structure of soil is stabilized by microbial exudation of hydrophobic extracellular proteins and polysaccharides (e.g. Baumert et al., 2018; Chenu & Cosentino, 2011; Hallett & Young, 1999) and enmeshment by fungal hyphae (Chenu & Cosentino, 2011).…”

Section: Biological Agents Of Soil Structure Dynamicsmentioning

confidence: 99%

A framework for modelling soil structure dynamics induced by biological activity

Meurer

Barron

Chenu

et al. 2020

Global Change Biology

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Soil degradation is a worsening global phenomenon driven by socio‐economic pressures, poor land management practices and climate change. A deterioration of soil structure at timescales ranging from seconds to centuries is implicated in most forms of soil degradation including the depletion of nutrients and organic matter, erosion and compaction. New soil–crop models that could account for soil structure dynamics at decadal to centennial timescales would provide insights into the relative importance of the various underlying physical (e.g. tillage, traffic compaction, swell/shrink and freeze/thaw) and biological (e.g. plant root growth, soil microbial and faunal activity) mechanisms, their impacts on soil hydrological processes and plant growth, as well as the relevant timescales of soil degradation and recovery. However, the development of such a model remains a challenge due to the enormous complexity of the interactions in the soil–plant system. In this paper, we focus on the impacts of biological processes on soil structure dynamics, especially the growth of plant roots and the activity of soil fauna and microorganisms. We first define what we mean by soil structure and then review current understanding of how these biological agents impact soil structure. We then develop a new framework for modelling soil structure dynamics, which is designed to be compatible with soil–crop models that operate at the soil profile scale and for long temporal scales (i.e. decades, centuries). We illustrate the modelling concept with a case study on the role of root growth and earthworm bioturbation in restoring the structure of a severely compacted soil.

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Root Exudates Induce Soil Macroaggregation Facilitated by Fungi in Subsoil

Cited by 148 publications

References 88 publications

Whole-profile soil organic matter content, composition, and stability under cropping systems that differ in belowground inputs

Whole-profile soil organic matter content, composition, and stability under cropping systems that differ in belowground inputs

The Contribution of Microorganisms to Soil Organic Carbon Stock Under Fertilization Varies among Aggregate Size Classes

A framework for modelling soil structure dynamics induced by biological activity

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