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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Soil formation / Soil state factors and the erosion-formation balance

Soil state factors and the erosion-formation balance

How climate, organisms, relief, parent material and time shape soil properties such as where organic carbon sits in the profile, and whether erosion or soil production dominates a landscape.

Boundary: where this process starts

Starts with: Climate, vegetation, relief, parent material and time set soil properties

Boundary: where it ends

Ends after: Topsoil (0-20 cm) concentrates organic carbon and roots; Mid-depth soil (20-40 cm) stores carbon with fewer roots

PARTICIPANTSRESOURCESSoilParent materialClimateOrganismsTopographyOtherparticipantsSoil organicmatterWaterOrganic carbonRockClay mineralsImpact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.40% topsoilImpact +2 of 5. Click for details and evidence.20% mid-depthImpact +3 of 5. Click for details and evidence.40% subsoilImpact 02 of 5. Click for details and evidence.Impact 02 of 5. Click for details and evidence.Impact 02 of 5. Click for details and evidence.Impact -3 of 5. Click for details and evidence.Impact -2 of 5. Click for details and evidence.Climate, vegetation, relief, parent material and time set soil properties: uses WaterClimate, vegetation, relief, parent material and time set soil properties: uses RockWhere soil organic carbon sits in the top metre: uses Soil organic matterWhere soil organic carbon sits in the top metre: uses Organic carbonTopsoil (0-20 cm) concentrates organic carbon and roots: uses Soil organic matterTopsoil (0-20 cm) concentrates organic carbon and roots: uses Organic carbonMid-depth soil (20-40 cm) stores carbon with fewer roots: uses Soil organic matterSubsoil below 40 cm holds old, mineral-bound carbon: uses Soil organic matterSubsoil below 40 cm holds old, mineral-bound carbon: uses Clay mineralsErosion versus soil production balance: uses Soil organic matterErosion versus soil production balance: uses Watershapes the soil moistureregimeWater: shapes the soil moisture regimeparent material sets thestarting pointRock: parent material sets the starting pointconcentrated near thesurfaceSoil organic matter: concentrated near the surfacestored mostly in topsoilOrganic carbon: stored mostly in topsoilconcentrated in the toplayerSoil organic matter: concentrated in the top layerconcentrated near theroot zoneOrganic carbon: concentrated near the root zonestored at moderate depthSoil organic matter: stored at moderate depthpersists as old,mineral-bound materialSoil organic matter: persists as old, mineral-bound materialbind and protect carbonClay minerals: bind and protect carbonlost when erosionoutpaces formationSoil organic matter: lost when erosion outpaces formationdrives erosion lossesWater: drives erosion lossesStart: Soil statefactors and theerosion-formati…STARTStart: Soil state factors and the erosion-formation balanceEnd: Soil state factorsand theerosion-formati…ENDEnd: Soil state factors and the erosion-formation balanceClimate, vegetation,relief, parent materialand time set so…📄1Climate, vegetation, relief, parent material and time set soil propertiesWhere soil organiccarbon sits in the topmetre📄1Where soil organic carbon sits in the top metreTopsoil (0-20 cm)concentrates organiccarbon and roots📄1Topsoil (0-20 cm) concentrates organic carbon and rootsMid-depth soil (20-40cm) stores carbon withfewer roots📄1Mid-depth soil (20-40 cm) stores carbon with fewer rootsSubsoil below 40 cmholds old,mineral-bound carbon📄1Subsoil below 40 cm holds old, mineral-bound carbonErosion versus soilproduction balance↘📄1Erosion versus soil production balance
Line thickness = size of impact (1 to 5)% on a line = chance a fork takes that branch📄 = pieces of evidence on a stepNegative effectLoops backHypothesisResource used up (arrow into the step)Resource used, not used upResource made or released (arrow out of the step)
What am I looking at? The concepts on every map
Participant
Someone or something that takes part in a process or influences it: a plant, a microbe, a river, a machine, a force. Participants are the rows of a map.
Resource
Something a step uses or uses up: water, oxygen, sunlight, a tool. Each step has an arrow down to the resources it uses.
Step
One thing that happens in a process. Every step has at least one participant and carries evidence.
Decision fork
A step where the process can go several ways. Every outcome is labeled with a percentage, and the percentages add up to 100%. It is not limited to yes or no.
Loop
A line that carries the process back to an earlier step. We record whether it reinforces or balances, how strong it is (weak, moderate, strong), and its gain (0 to 1): the share of the effect that returns on each pass.
Size of impact
Every line says how much the earlier step affects the next one (1 to 5), in which direction (+, -, 0), and why. Thicker lines mean bigger impact.
Evidence
The support for a claim: a source and what it shows. Every step, line, change and vote needs it. Click any step or line to read its evidence.
Boundary
Where a process starts and where it ends. Every process, and every subprocess, has a start and an end.
Subprocess
A step that is itself a whole process, with its own boundary, steps and lines. Click a step marked ↘ to open it. Subprocesses nest as deep as the evidence goes.
Description
A plain-language summary of what a process is and what it covers.
Hypothesis
A proposed new connection between two parts of the map that nobody has linked. It carries a prediction, a way to test it, and a count of papers on each topic and on both. It is an unverified idea until someone tests it.

Inside this process

Erosion versus soil production balance

Tillage and bare ground raise erosion above the rate at which weathering produces soil; thinner soil holds less water and supports less plant cover, which accelerates further erosion.

Every step, with its evidence

The same information as the map, as a list you can search and share. Click a participant or resource to see everywhere it appears.

Climate, vegetation, relief, parent material and time set soil properties
ClimateOrganismsTopographyParent materialWaterRock
Evidence (1) · added by Broad
  • Brantley 2007, Crossing disciplines and scales to understand the critical zone, Elements, doi:10.2113/gselements.3.5.307: Soil properties reflect the combined action of climate, biota, relief, rock and time. (confidence 0.7)
⑂ Where soil organic carbon sits in the top metre
PlantsSoilSoil organic matterOrganic carbon
Evidence (1) · added by Broad
  • Jobbagy & Jackson 2000, The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecological Applications, doi:10.1890/1051-0761(2000)010[0423:tvdoso]2.0.co;2: Global profiles hold roughly 40% of top-metre SOC in the top 20 cm, about 20% at 20-40 cm and 40% below; shares vary with biome. Approximate. (confidence 0.55)
Topsoil (0-20 cm) concentrates organic carbon and roots
PlantsSoil faunaRootsSoil organic matterOrganic carbon
Evidence (1) · added by Broad
  • Jobbagy & Jackson 2000, The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecological Applications, doi:10.1890/1051-0761(2000)010[0423:tvdoso]2.0.co;2: SOC is concentrated near the surface with vegetation type controlling depth distribution. (confidence 0.65)
Mid-depth soil (20-40 cm) stores carbon with fewer roots
SoilPlant rootsSoil organic matter
Evidence (1) · added by Broad
  • Jobbagy & Jackson 2000, The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecological Applications, doi:10.1890/1051-0761(2000)010[0423:tvdoso]2.0.co;2: SOC declines with depth. (confidence 0.6)
Subsoil below 40 cm holds old, mineral-bound carbon
SoilMineralsSoil organic matterClay minerals
Evidence (1) · added by Broad
  • Jobbagy & Jackson 2000, The vertical distribution of soil organic carbon and its relation to climate and vegetation, Ecological Applications, doi:10.1890/1051-0761(2000)010[0423:tvdoso]2.0.co;2: A substantial share of SOC lies below 40 cm. (confidence 0.6)
↘ Erosion versus soil production balance
SoilPlantsRainSoil organic matterWaterNitrogen
Evidence (1) · added by Broad
  • Montgomery 2007, Soil erosion and agricultural sustainability, PNAS, doi:10.1073/pnas.0611508104: Erosion under conventional agriculture exceeds soil production and geological erosion rates by large factors (one to two orders of magnitude). (confidence 0.75)