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Resource: used or used up in processes

Calcium

Appears in 34 processs and 60 steps. Everything below is linked: open a process to see it in context.

Top processes

Base cation cycling (calcium, magnesium, potassium, sodium)

9 steps

Cation exchange, pH and soil solution chemistry

4 steps

Cations held on exchange sites (Ca, Mg, K, Na, NH4, Al, H)
Leaching removes displaced base cations, base saturation falls, Al3+ rises below pH 5
Salinity and sodicity
and 1 more in this process

Chemical weathering: CO2-driven dissolution and CO2 consumption

4 steps

Fossil and geologic carbon exchange

3 steps

Mineral weathering and parent material

3 steps

Aluminium toxicity and liming of acid soils

3 steps

Show 28 more processes

Nutrient availability and leaching

2 steps

Mineral-associated organic matter (MAOM) formation

2 steps

Living soil system

2 steps

Pedogenic carbonate accumulation and calcrete formation

2 steps

Soil inorganic carbon: pedogenic carbonate formation and dissolution

2 steps

Biological weathering by roots, mycorrhizal fungi and microbes (plants speed weathering about 2-10 fold)

2 steps

Weathering, erosion and sediment transport

1 step

Chemical weathering dissolves silicates and carbonates, consuming Carbon dioxide

Aggregate formation and pore structure

1 step

Polyvalent cations and oxides bridge clay to organic matter

Occlusion in aggregates

1 step

Primary particles flocculate with clay and cations

Soil sulfur cycling

1 step

Sulfate leaches with calcium, magnesium and potassium into drainage water

Nitrification-driven acidification of ammonium fertilised soil

1 step

Nitrate leaches with Calcium and Magnesium, leaving net acidity

Silicate weathering rate control and CO2 drawdown

1 step

Proton-promoted dissolution of feldspar and mica releases base cations and silica

Soil CO2 and biotic enhancement of weathering

1 step

Plant uptake removes released cations, keeping solution undersaturated

Clay mineralogy and organic matter set cation exchange capacity

1 step

Higher CEC retains Ca, Mg, K and NH4 against leaching

Sequential soil pH buffer systems

1 step

Carbonate buffer range (about pH 8.6 to 6.2): calcite dissolves and consumes acid

Biochar and charcoal in soil

1 step

Ash carbonates raise pH and reduce Aluminum toxicity

Salinity and sodicity

1 step

Reclamation: gypsum supplies Calcium and leaching removes Na

Pedogenesis and soil horizon development

1 step

Calcification: carbonates and salts accumulate at the depth of wetting

Soil disturbance (fire, tillage, drought) and recovery

1 step

Fire adds ash nutrients and pyrogenic carbon and mineralizes nitrogen

Atmospheric dust deposition and loess as soil parent material

1 step

Dust adds phosphorus, calcium and fine particles to downwind soils (Saharan dust supplies the Amazon with about 22,000 t P per year)

Pyrite oxidation and acid sulfate weathering

1 step

Calcite and exchangeable bases neutralise acid (CaCO3 consumes 2 mol H+ per mol) and raise pH

Rhizobia-legume signalling and nodule formation

1 step

Root-hair LysM receptor kinases (NFR1 and NFR5 in Lotus) perceive Nod factors and trigger calcium spiking

Shrink-swell cycles and crack dynamics in clay soils

1 step

Wetting hydrates the cations between smectite layers: Ca-smectite swells to about 1.9 nm basal spacing, whereas Na-smectite at low salt swells osmotically beyond 4 nm

Mineral surface area, reactive metals and the saturation of mineral-associated carbon

1 step

In neutral to alkaline soils exchangeable calcium and clay matter more than clay content alone, while reactive Al and Fe explain most variation in acidic soils

Drainage, groundwater recharge and runoff (about 65 percent of rain returns to air, 35 percent runs off)

1 step

Percolating water flushes dissolved ions (calcium, magnesium, nitrate, bicarbonate) out of the profile

Chronosequence: limiting nutrient and nutrient source shift as soil ages

1 step

Atmospheric dust becomes the main source of rock-derived nutrients

Soil formation

1 step

Roots, fungi and burrowers engineer soil formation

Roots, fungi and burrowers engineer soil formation

1 step

Deep roots take up cations from subsoil and return them in litter (biological pumping)

Often found with

Water 21 Magnesium 17 Potassium 16 Plant roots 14 Clay minerals 11 Bicarbonate 9 Hydrogen ions 9 Drainage water 8 Soil water 8 Calcite 8 Carbon dioxide 7 Clay minerals 7

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