Soils

agriculture supports biodiversity habitat for some organisms site of chemical reaction supports plants for climate regulation

the ability of soil to sustain plant growth

mixture of small pieces of different rocks or minerals particles = round

fine sand/clay carried by running water and deposited as a sediment larger than clay, smaller than sand

grained earth flat and platey

decomposition - cycling of nutrients

micro-organisms, spiders, insects, earthworms

water and air

essential for all organisms good soils allow good drainage, but retain enough for soil biota dissolves nutrients

macro - phosphorus, nitrogen, potassium micro - boron, cobalt, copper, iron, manganese, magnesium shortage of nutrients limits plant growth harmful metals adsorb onto surface of clay particles

most processes = aerobic well aerated = more fertile aerobic = faster decomposition

more DOM = fertile soils binds soils increases nutrients, water retention and food for soil biota

fertile soils = 5.5-7 acidic soils = increased leaching and damage to root cell membranes alkaline soils = phosphates are insoluble

detritivores break down DOM and release nutrients decomposers break down DOM and secrete digestive enzymes nitrogen fixing bacteria nitrifying bacteria mycorrhizal fungi

controlled by different mineral particles clay = small silt = medium sand = small

soil particles from aggregates (peds) crumb peds = small and round = good drainage/aeration/root penetration platy peds = large and flat = decreases drainage/aeration/root penetration

deeper soil s= dry out rapidly root anchorage

large and spherical = better drainage quicker in sand than clay soils

more water drawn up in clay soils as water content is higher

higher in sandy soils as more porous

higher in clay as more water available so more nutrients dissolved some able to adsorb to clay particles

higher water content = higher thermal capacity

higher in sandy soils

higher in sandy soils