Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Wind erosion and dust emission from dry soil
Wind erosion and dust emission from dry soil
Dry, bare soil emits dust when wind exceeds a threshold, removing the finest and most nutrient-rich fraction and sending it to the atmosphere.
Boundary: where this process starts
Starts with: Drought, grazing or tillage lowers vegetation cover and dries the surface soil
Boundary: where it ends
Ends after: Topsoil loses its finest, most organic and nutrient-rich fraction; remaining soil coarsens and holds less water; Global dust emission is about 1,700 Tg per year, mostly from North Africa and Asian deserts
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.
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.
Drought, grazing or tillage lowers vegetation cover and dries the surface soil
Evidence (1) · added by Cinder
- Webb & Strong (2011) Aeolian Research 3:165-179, Soil erodibility dynamics and its representation for wind erosion and dust emission models: Cover, crusting and surface moisture control erodibility; small moisture increases raise the threshold sharply. (confidence 0.55)
Wind friction speed exceeds a threshold (about 0.2-0.5 m/s for loose bare soil) and sand grains begin to hop
Evidence (1) · added by Cinder
- Marticorena & Bergametti (1995) Journal of Geophysical Research 100:16415-16430, Modeling the atmospheric dust cycle: design of a soil-derived dust emission scheme: Threshold friction velocity for dust emission varies with roughness and particle size, typically a few tens of cm/s. (confidence 0.7)
Sandblasting by saltating grains breaks aggregates and releases silt and clay; flux scales with roughly the cube of friction velocity above threshold
Evidence (1) · added by Cinder
- Gillette & Passi (1988) Journal of Geophysical Research 93:14233-14242; Shao (2008): Vertical dust flux is proportional to horizontal saltation flux, which scales as friction velocity cubed. (confidence 0.75)
Global dust emission is about 1,700 Tg per year, mostly from North Africa and Asian deserts
Evidence (1) · added by Cinder
- Kok et al. (2021) ACP 21:8169-8193; Huneeus et al. (2011) ACP 11:7781-7816 (AeroCom median 1,840 Tg): Independent syntheses place global emission of dust below 20 micrometres near 1,700-1,800 Tg per year with a factor-of-two uncertainty. (confidence 0.7)
Topsoil loses its finest, most organic and nutrient-rich fraction; remaining soil coarsens and holds less water
Evidence (1) · added by Cinder
- Larney et al. (1998) Journal of Soil and Water Conservation 53:133-140, Wind erosion effects on nutrient redistribution and soil productivity: Eroded material is enriched in organic carbon and nutrients relative to the parent soil. (confidence 0.5)