Scsc 301 exam 2

macrofauna

mammals, insects, plants, mosses

Mesofauna

nematodes, protozoa

microorganisms

fungi, bacteria, actinomycetes, algae

best environment for soil organisms

warm and wet, neutral pH

pore space

1 - BD/PD

short term tillage affect

decrease BD and increase porosity

long term tillage affect

increase BD and decrease porosity

hue

color

value

low value = dark, organic matter present

chroma

how much color, 6 or more = likely red or orange

earthworms

alter physical and chemical properties of soil

termites

do not benefit soil, contribute to methane emmisions

nematodes

abundant in moist sandy soils, no oxygen use, predators

protozoa

thrive in moist, well drained soils near the surface

soil algae

symbiotic association with fungi, photosynthesis

soil fungi

pH 4-5.5, yeasts, molds, mushrooms

mycorrhizae

obtains sugar directly from the plant root, improves P, protect plant from infections

bacteria

pH 6-7, extremely diverse, rapid reproduction, N reactions, OM breakdown

aerobic

mineralization of C, formation of humus, requires O

actinomycetes

OM degradation, pH 7-8.5, produces antibiotics

anaerobic

slow, no oxygen required, usually due to flooded

factors promoting rapid decomposition

warm, neutral pH, high N

high C/N ratio

competition for N, immobilization

low C/N ratio

plentiful N, mineralization and plant availability of N

biomass

living

detritus

dead, identifiable

humic substances

not inorganic, but unidentifiable

non-humic substances

cannot identify, can classify chemically

humus

colloidal, negatively charged, high water holding capacity, dark colored

low soil organic matter

warm and dry

high soil organic matter

cool and wet

polar

causes adhesion and cohesion

matric potential

micropores

osmotic potential

water moves toward salt (plant uptake)

gravitational

macropores

positive potential

water moves freely with gravity

0 kPa

saturation

-10 to -30 kPa

field capacity, water movement via capillary

-1500 kPa

permanant wilting point

<-1500 kPa

hygroscopic water, water doesn't move

Unsaturated water flow

primarilly capillary

preferential water flow

Primarily gravitational

percolation

water moving downward through soil

leaching

ions moving with water into soil

Ksat

sand > loam > clay