Soils, Soil Processes & Decomposition

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

Soil formation processes – Laterization Silicate 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 gone Red or Yellow color Infertile, rapid and almost direct recycling; little nutrient storage

Entisols Udipsamment

Entisols EudifluventLithic Ustorthent

Inceptisols Typic HydrandeptUmbric Vitandrept

Alfisols Typic Hapudalf

Ultisols Typic 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 eluviation B = illuviation of organic, Al, & Fe Distribution world-wide, greatest in boreal zone Also 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 HaplaquolTypic Argiudoll

Typic Argiustol Typic Haplustol

Aridisols Typic Haplargid Petrocalcic Paleargid

Typic Salorthid

Histisols Limnic Medisaprist

Vertisols