Paper · 2022 · European Journal of Soil Science

RUSSELL REVIEW Are plant roots only “in” soil or are they “of” it? Roots, soil formation and function

Peter J. Gregory

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claims
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verbatim quotes
62
citations
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research areas
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Open access · cc-by

Abstract

Abstract Roots are near‐ubiquitous components of soils globally but have often been regarded as separate from the soil rather than a substantial factor in determining what soil is and how it functions. The start of rapid soil formation commenced about 400 million years ago with the emergence of vascular plants and the evolution of roots and associated microbes. Roots and associated microorganisms contribute significantly to soil formation by altering rocks and soil minerals through a variety of biogeochemical processes and supply carbon to a depth that can have long residence times. Living root inputs of carbon via rhizodeposits are more efficient than shoot and root litter inputs in forming slow‐cycling, mineral‐associated soil organic carbon pools. The current functionality of soils in providing food and fuel and fibres, supplying plant nutrients, filtering water and flood regulation, and disease suppression are all dependent on the activities of plant roots. Roots are actively communicating and collaborating with other organisms for mutual benefit, and the signals underlying this modulation of the rhizosphere microbiome are being identified. In this review I examine how plant roots (an organ not an organism) affect soil formation and function and conclude that, from several perspectives, roots are not just “in” soil but “of” it and that definitions of soil should recognise this. A possible definition is: “Soils are altered surficial rock or sediment, composed of organic matter, minerals, fluids, and organisms whose formation and functionality are influenced by biogeochemical weathering and interactions of these components with plant roots.” Highlights Paleoclimatic and paleosoil research shows the key role of roots and mycorrhiza in soil formation. Deep roots and living root inputs are substantial contributors to long‐term C storage. Root/microbe signalling facilitates mutualistic symbioses, nutrient uptake and disease suppression. Definitions of soil should explicitly include roots as an important component of the soil system.

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Claims 5

Observationobservedreview summarypositivebasis n/a

Claim · model-written summary

Roots and associated microorganisms contribute to soil formation through mineral alteration and deep carbon supply.

Taxon
plant rootst0
Organ / stage
Rootse0
Outcome
soil formatione0
Qualifier
altering rocks and soil mineralse0

Verbatim

e0

“Roots and associated microorganisms contribute significantly to soil formation by altering rocks and soil minerals through a variety of biogeochemical processes and supply carbon to a depth that can have long residence times.”

✓ located verbatim in the source · abstract, characters 364–589 · show in text ↑
t0

“plant roots”

✓ located verbatim in the source · title, characters 19–30 · show in text ↑
Associationobservedreview summarypositivebasis n/a

Claim · model-written summary

Living root carbon inputs form slow cycling mineral associated soil carbon more efficiently than litter inputs.

Taxon
plant rootst0
Organ / stage
roote0
Outcome
slow‐cycling, mineral‐associated soil organic carbon poolse0
Direction
more efficiente0
Comparator
shoot and root litter inputse0

Verbatim

e0

“Living root inputs of carbon via rhizodeposits are more efficient than shoot and root litter inputs in forming slow‐cycling, mineral‐associated soil organic carbon pools.”

✓ located verbatim in the source · abstract, characters 590–760 · show in text ↑
t0

“plant roots”

✓ located verbatim in the source · title, characters 19–30 · show in text ↑
Associationobservedreview summarypositivebasis n/a

Claim · model-written summary

Soil functions including nutrient supply, water filtering and disease suppression depend on root activity.

Taxon
plant rootst0
Organ / stage
plant rootse0
Outcome
current functionality of soilse0

Not reportedDirection

Verbatim

e0

“The current functionality of soils in providing food and fuel and fibres, supplying plant nutrients, filtering water and flood regulation, and disease suppression are all dependent on the activities of plant roots.”

✓ located verbatim in the source · abstract, characters 761–975 · show in text ↑
t0

“plant roots”

✓ located verbatim in the source · title, characters 19–30 · show in text ↑
Observationobservedreview summarypositivebasis n/a

Claim · model-written summary

Root communication with other organisms supports mutual benefit.

Taxon
plant rootst0
Organ / stage
Rootse0
Outcome
communicating and collaborating with other organisms for mutual benefite0

Verbatim

e0

“Roots are actively communicating and collaborating with other organisms for mutual benefit”

✓ located verbatim in the source · abstract, characters 976–1066 · show in text ↑
t0

“plant roots”

✓ located verbatim in the source · title, characters 19–30 · show in text ↑
Recommendationauthor interpretationreview summarybasis n/a

Claim · model-written summary

The review recommends that definitions of soil recognize roots as a component.

Taxon
plant rootst0
Outcome
definitions of soil should recognise thise0

Verbatim

e0

“definitions of soil should recognise this”

✓ located verbatim in the source · abstract, characters 1362–1403 · show in text ↑
t0

“plant roots”

✓ located verbatim in the source · title, characters 19–30 · show in text ↑