Soils, Soil Processes & Decomposition

Surface area increases as particle size decreases.Surface area influences ability to hold water and nutrients.

Soil formation processes – LaterizationSilicate rich parent material

Free polyphenols disperse clays & assist movement f/A->B Older, more intense weathering

Rapid decomposition of organics

Clays weather to Al and Fe oxides - SiO4 goneRed or Yellow color

Infertile, rapid and almost direct recycling; little nutrient storage  

EntisolsUdipsamment

Entisols

Eudifluvent Lithic Ustorthent

Inceptisols

Typic Hydrandept Umbric Vitandrept

AlfisolsTypic Hapudalf

UltisolsTypic Hapudult

Oxisols Tropeptic Eutrorthox

Soil formation processes – Podsolization

Substrate usually well-drained quartz sand, acid, igneous

Transport of Fe and Al by soluble organic compounds. Plants from low N or low P soils produce polyphenols

E = intense eluviationB = illuviation of organic, Al, & Fe

Distribution world-wide, greatest in boreal zoneAlso in temperate and tropical zones on acid quartz sands

End point = acid, low nutrients     Bleached E and Dark B with Organics, Fe and Al in B

Spodisols

Aeric HaplaquodTypic Haplorthod

Soil formation processes – Calcification

Drier sites; Calcium not leached out of soil profile

Gradient of decreasing precipitation matches thinner A horizon

A horizon high in organic content, mostly roots of grass

Often highly fertile

Climate/disturbance appears unsuitable for trees

Molliosols

Typic Haplaquol Typic Argiudoll

Typic Argiustol Typic Haplustol

Aridisols

Typic Haplargid Petrocalcic Paleargid

Typic Salorthid

HistisolsLimnic Medisaprist

Vertisols