plant tissue is 50 to 90 percent

turgitidy

one pound of biomass requires 600 gallons

transpiration

photosynthesis

other chemical reactions

nutrient movement

root growth

plants wilt

guard cells use stomata temporary wilting power

chronic water stress, yellow leaves, loss of leaf turgor, curled or scorched leaves

pernament wilting point

symptoms similar to nutrient defficiencies

fungal diseases and root decay

reduced root respiration (low oxygen)

some plants may die within hours or days

gravimetric water = moist weight-dry wt

      content %                           dry weight      x 100

volumentric                 volumetric wate

water weight                 total soil volume

theta %                                  (times 100)

formed by waters possitive and negative bonds

attraction to other water

in soil cohesion water is available

attraction to soil, cell wall

in soil held tightly

potential amount of water relative to a unit volume of pure water

higher potential, more available to plants

lower is less available

water is attracted to soil particles, other water particles, and disolved solutes. this lowers water potential and makes it less available to plants

measured with tensiometer

water moves from wet to dry soil

after water drains, there is little movement

dry soils prefer root growth more than top growth

irrigation favors shallow and sparse roots

terraces

contour tillage

strip-cropping

aeration

subsoiling

conservation tillage

mulch

opposites attract: a small - charge will attract a + charged ion and repel a - ion

*plant nutients held and not washed away

keeps pollutants from entering the ground water or surface water

1% clay=.5 CEC

1% of humus=2 CEC

plant nutrients

(essential element)

the lack of an elemnt that stops growth or reproduction

directly involved in plant nutrition

shortage only corrected by supply

17: C, H, O =95% of all plants needs supplied by water.

NPKCaMgSBCuClFeMnMoNiZn=soil or soil solution

NaSiCo=not essential but benificial

all weathered from rock but N

NKCaMgPS

NPK< primamry macronutrients-limit plant growth

CaMgS secondary macronutrients. usually not limiting plant growth

BCuClFeMnMoNiZn

used in small amounts

Fe-used to make chlorophyll

charged atoms or ions

cation: + ca mg k

anion: - cl so4 no3 po

soil paarticles absorb ions

plant roots absorb ions

soil minerals- except N

organic matter- lots of N, and anions (phosphate and sulfate)

absorbed nutrients- nutrients held by attraction to clay (cations) and humus (cations and anions)

dissolved ions-soil solution- only form absorbed by plants; easily leached too

granite and limesstone

k

na ca

k si

other types

Mg Fe Na Ca Mn Ba

mostly clay and humus

slight electrical charge attracts ions

three types

silicate

oxide

humus

Tiny crystal of secondary mineral formed in the soil from weathered products of primary minerals like feldspar or mica

primary-ions in solution

ions in soil-crystilization

clay mineral (secondary)

silica tetrahedron

four oxygens, 1 silicate

alumina octahedron

six hodroxyl, surounding a aluminum

some are 1:1 clays

like an opened faced sandwich with a single silicate layer next to an alumina layer

H bonding holds layers so they don't absorb water between layers and do not expand

usually 2:1 clays

sandwhich-like. with an aluminum layer inbetween two silica layers

most absorb water between the layers and are called expanding clays

negative charge on silicate clay minerals

2 main sources

edge charge, oxygen ions at edge, PH dependent charge.

acidity  (H+) (-)charge

internal charge- Isomorphous substitution: e.g. AL+3 substitues for Si+4, or Mg+2 substitiues for Al+3 leaving a negative charge ingternally. Not PH dependent. Pernament charge

two octahedral structures sheets with Fe and Al

often formed by weatheringsilicate clays

Don't swell and have trouble holding cations (low CEC)

silica leached out leaving behind the oxides- no (-) internal charges

common in highly weathered trpical soils

these soils are (+) charged (hold anions), they have significant AEC

Anion exchange

(AEC exchange)

hydrogen cocalently bonded on "the edge" produce a net possitive charge which can attract anions

as surface becomes more possitive, cations disperse

but increased potential to hold (NO3-)

Most clays have some AEC, Fe, and Al oxide clays have moderate AEC, organic colloids and Allophanehave high AEC

cation exhcange capacity and anion exchange capacity

consits of

2:1 clays, mild weathering

(cation)

1:1 moderate clays, intermediate weathering

Mostly Fe, Al oxide  clays. strong weathering

(anion)

INderect affects

PH extremes can reduce availibility of nutrients in plants

reduce the soil micororganism population

increase the abundance of toxic elements

Organic matter contains many nutrients and water

+ and - charges attract cations and anions

absorb nutrients more strongly than clays

decays over time into CO2 and nutrients are released

fertilizers affect of origin of availibility

parent material: slowly available

organic matter: moderatly available

synthetic matter: immediatly available

Nitrogen- N2 gas and CH4 (haber process)

NH2

NH4NO3

CO(NH2)

Phosphorous-mined rock-only 8% P converted to superphosphate 45% P

Potassium mined as KCl

Comercial fertilizers

Each essential nutrient can be applied as commercial fertilizer

NPK bitches

N-resevoir is only in organics, easily leached as NO3- bacteria complete for N

P= short supply, resevoir is mostly in organics. rapidly becomes unavailable at ph<6.

Binds to (Al and Fe oxides)

K-very soluable, excess rapidly leached from rooting zone

bring soil into best condition

leave plant residue

adjust PH to about 6.5

add sufficient fertilizer to make up for losses due to crop removal

do not over fertilize

Organic matter in soil

source

living forms of OM in and above the soil

3 to 4x more soil OM that in living biomass

structure/arregation

color/temperature

water holding

CEC- nutrient bonding

nutrient supplying

biodiversity

erosion control

water quality

cellulose

lignins

proteins

amino acids

sugars

starch

fats and waxes

(availibility for food for microbes by rank)

Labile-easily decomposed

recalcitrant-resistant to decomposition

solution

fragmentation

decay

huminification

process that decreases carbon, increases recalcitrant materials in rich Nitrogen leaving "humus" which decays slowly and provides essential nutriants

living organisms

identifiable dead tissue

nonliving (non-tissue - a product of decomposition called humus)

tremendous surface area

very high CEC, WHC

supplies essential plant nutrients

attaches to particles to improve soil structure

decreases bulk density

impacts a dark color to soil surface

decreases erosion

Calculate bulk density in g/cm3.