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Earth's Systems / Biological processes / Terrestrial ecosystem functioning / Living soil system / Mineral weathering and parent material / Pedogenic age sequence: from apatite phosphorus to occluded phosphorus

Pedogenic age sequence: from apatite phosphorus to occluded phosphorus

How soil phosphorus changes over thousands to millions of years from primary apatite to organic, sorbed and finally occluded forms, shifting ecosystems from nitrogen to phosphorus limitation.

Boundary: where this process starts

Starts with: Young soil: primary apatite supplies phosphorus and dominates total P

Boundary: where it ends

Ends after: Old soil: P-limited, ecosystem relies on tight recycling and dust inputs

PARTICIPANTSRESOURCESParent rockPlant rootsIron oxidesApatiteSoil microbesOtherparticipantsPhosphorusPhosphatePrimarymineralsSoil organicmatterIron oxidesImpact +3 of 5. Click for details and evidence.Impact +4 of 5. Click for details and evidence.Impact -3 of 5. Click for details and evidence.Impact 03 of 5. Click for details and evidence.Impact +3 of 5. Click for details and evidence.↻ balances · moderate · 0.3 Phosphatases andImpact -3 of 5. Click for details and evidence.Young soil: primary apatite supplies phosphorus and dominates total P: makes PhosphorusmakesYoung soil: primary apatite supplies phosphorus and dominates total P: uses up Primary mineralsuses upApatite dissolves; P moves into plant biomass and organic matter: uses up Phosphateuses upApatite dissolves; P moves into plant biomass and organic matter: uses Soil organic matterPhosphate sorbs to Fe and Al oxides and becomes occluded: uses up Phosphateuses upPhosphate sorbs to Fe and Al oxides and becomes occluded: uses Iron oxidesOld soil: P-limited, ecosystem relies on tight recycling and dust inputs: uses Phosphorusreleased from apatitedissolutionPhosphorus: released from apatite dissolutiondissolved to supplyphosphorusPrimary minerals: dissolved to supply phosphorustaken up by plantsPhosphate: taken up by plantsincorporated intoorganic matterSoil organic matter: incorporated into organic mattersorbed by mineralsurfacesPhosphate: sorbed by mineral surfacesprovide sorption sitesIron oxides: provide sorption sitestightly recycled withinsystemPhosphorus: tightly recycled within systemStart: Pedogenic agesequence: from apatitephosphorus to occlud…STARTStart: Pedogenic age sequence: from apatite phosphorus to occluded phosphorusEnd: Pedogenic agesequence: from apatitephosphorus to occlud…ENDEnd: Pedogenic age sequence: from apatite phosphorus to occluded phosphorusYoung soil: primaryapatite suppliesphosphorus a…📄1Young soil: primary apatite supplies phosphorus and dominates total PApatite dissolves; Pmoves into plantbiomass and organ…📄1Apatite dissolves; P moves into plant biomass and organic matterPhosphate sorbs to Feand Al oxides andbecomes occluded📄1Phosphate sorbs to Fe and Al oxides and becomes occludedOld soil: P-limited,ecosystem relies ontight recycling a…📄1Old soil: P-limited, ecosystem relies on tight recycling and dust inputs
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.

Young soil: primary apatite supplies phosphorus and dominates total P
ApatiteParent rockPhosphorusPrimary minerals
Evidence (1) · added by Cinder
  • Walker & Syers 1976, Geoderma 15:1: Apatite P declines steadily during pedogenesis (confidence 0.9)
Apatite dissolves; P moves into plant biomass and organic matter
Plant rootsSoil microbesPhosphateSoil organic matter
Evidence (1) · added by Cinder
  • Walker & Syers 1976: Organic P and non-occluded P increase then decline (confidence 0.85)
Phosphate sorbs to Fe and Al oxides and becomes occluded
Iron oxidesAluminum oxidesPhosphateIron oxides
Evidence (1) · added by Cinder
  • Walker & Syers 1976: Occluded P grows as soils age (confidence 0.85)
Old soil: P-limited, ecosystem relies on tight recycling and dust inputs
PlantsWind-blown dustPhosphorusDust
Evidence (1) · added by Cinder
  • Chadwick et al. 1999, Nature 397:491: Hawaiian sequence: dust becomes the main P source over 4 Myr as rock P is exhausted (confidence 0.85)