AGRY 270

Hue

Hue is found in the upper right of chart is the hint

Value

Lightness and darkness of the color

Chroma

bottom of the chart, amount of tint you add

10 YR 6/4

Light brownish yellow

10YR 3/4

Brown

10 YR 4/4

Brown

10 YR 3/1

Dark grey

10 YR 3/3

Light brown

Oxidized Iron ( Fe+3)

red, brown, tan, yellow

oxidation-redox features

sandy brown, tan, grey-brown

Reduced Iron ( Fe+2)

grey

The Primary sources of soil color are

Iron in oxided state and inorganic matter

What colors do you see in the wall drained soils?

light brown ( bright)

what colors do you see in the poorly drained soils

grey

Between the two praire soils, which one has the greater accumulation of organic matter

Parr

Between the two forest soils, which one has the greater accumulation of organic matter?

brookston

Compare the surface horizons of the well drained prairie and the well drained forest soil, do soils developed under prairie vegatation or forest vegation contain more organic matter?

Parr

sand

0.5-2mm

silt

0.002-0.05 mm

clay

0-0.002 mm

Very Coarse

1.0-2.0mm

medium

0.25-0.5 mm

very fine

0.05-0.10mm

coarse

0.5-1.0 mm

fine

0.10-0.20 mm

how many textural class categories are there?

12

loam

gritty, sand-like, sticks together well

clay loam

equal part od sand, silk, clay and sticky

Clay

super stiff + sticky

Increasing the amount of silt would make a soil feel

smooth

Increasing the amount of sand would make a soil feel

gritty, course

if a soil feel gritty, the soil is in the middle of the triangle

loam

the 12 types of soil are

clay, sandy clay, silty clay, sandy clay loam, clay loam, silty clay loam, sandy loam, loam, silt loam

texture

describes the relative proportions of sand, silt and clay particles in soil, determining how gritty, smooth, or sticky it feels and affecting its water retention, drainage and air capacity

structure

the soil structure is the arrangement of soil particles into aggregates

Ped

Aggregates refer to the structure granular, platy, blocky, prismatic, and columnar

single grain

beach sand or dessert dunes —— lacks fine particles and organic matter bind to them

Massive

clay loam

Granular

consists of roughly spheroidal aggregates that may be separated from each other

Platy

characterized by relatively thin horizontal sheet like peds, may be found in both surface + subsurface horizons

subangular

these are found in b horizons, where they promote drainage, root penetration

angular

edges are blocky and sharp and rectangular faces are distinct

Prismatic

columnar + prismatic structures are characterized by vertically orientated prisms

Oi

Loose leaves and undecomposed organic debris

Oa

Matted and decomposed organic material

A

a mineral horizon containing Humus

E

A layer lighter in color and lower in organic matter than overlying a whose main feature is loss of silicate clay, iron

BE

Tranistion horizon

B

lluvival

BC

tranisitional horizon

R

bedrock

C

this horizon may be consisered to be similar to the original appearance of the solum

Fe reduction

Fe3+ + e- —————- Fe2+

Fe and Mn

The black spots and smear are due to manganese oxides, these are often present in poorly drained soils

Bright red and orange

Well drained

Soil is brown with hollow areas, soil with organic matter, soil is very red and orange

well drained

Soil that is very organge and yellow

Well drianed

Soils that are rocky, red, gray

poorly drained

Soils grey, red

poorly drained

red zones, and hydric soil

poorly drained

dark grey

poorly drained

Color indication or reduction

chromas of 2 or less are the greyish colorish colors which we consider of typical of fe2+

Texture

Proportion of each particle silt sand, silt, clay

Structure

arrangement of particles

Single-grained

sand

Massive

platy clay

Water

texture + structure are both important to plant water avaiblity. movement of water is slow in the top part of the triangle

Root growth

Root movement can also be impeded in very poor soils such as sand and loamy sands

Compaction

sand and grave is do not compact very easliy. clays are usually sticky enough to form a strong enough strcuture that also resist easy competiotn

Erosion , water

Sand detaches, easliy , hand to transport. clay hard to detach, easy to transport-silt easy to detach easy transport

Wind

Detaches and transport fine sands most easliy. Silts and clays usually crust or stick together

Tillage

Tillage is related to texture and structure, sands-easy to dig, silt, also easy to dig, most difficult

Water retention and storage

the amount of water stored in the soils is determined by the pore size-which is determined by soil and texture

Plant nutrition and soil fertility

Clays and organic matter give soil the ability to hold nutrients, of the soil has clay, then it has capacity for plant nutirents

crusting

formation of a hard dense layer on the soil the ability to hold nutrients, if the soil has clay, then it has capacity for plant nutrients

four steps in preparing a soil texture

Step 1, sample size 50g, step 2, remove organic matter with hydrogen peroxide leaving only sand, silt, and clay. step 3, chemical dispersion of the samples with sodium hexametaphosphate. the Na+ replaces the Ca++ on the negatively charged clay particles while the phosphates from a complex with calcium. step 4, Next mechanically disperse the sample in a blender

V

velocity of fall, in cm. per second

G

gravity

r

size of the particle

d1

density of liquid

ds

density of soild

n

viscosity of liquid

sand % is 40, silt % 38, clay 22, and soil texture

loam

Biologic activity

tomatoes grow bad in soil temps less than 56F, most plants have some tolerate to soil texture

Impact of mulches

covering soil with plastic can have a big impact. clear plastic can raise the soil temperature. black helps control weeds which grow up.

Solar absorption influenced by

aspect, albedo, and direction the soil faces

soil specific heat and conductivity is primarily influenced by

water content

Frost heaving

is important in perennial plants and can impact erosion because the particles that are lifted are easliy moved downslope

Soil moisture content

water has higher specifc heat than air meaning it requires more energy to change its temperature. wet soils warm up more slowly—- spring cool down more

Plant residues

mulch and plant residues act as a layer of insulation that buffers the soil from extreme air temparatures in the summer, they keep soil cooler by shading the surface from direct solar radiation

the larger the wheel

heavier the axel

increasing compaction,

increases the soil bulk and decreases the soil pore space

BD

oven dry soil weight/ total soil volume

PD

oven dry soil weight/ volume of soil solids

relation of bulk denisty and pore space

= [ 100- (BD/PD) x 100)]

What is the relationship of texture and bulk density

soil texture influences bulk density because particles size and pore distribution pack— sandy soils

The relationship of structure and bulk density?

soil structure controls bulk density have higher bulk density— by determining pore space between fine- textured aggregates

How does the compaction Bulk Density relationship affect plant roots and soil quality

As compaction increases, bulk density rises, pore space decreases, and roots lose access to oxygen, water and physical space to poor planet growth and long-term soil degradation.

Why does peat float?

peat floats because it has a low bulk density and once it gets staturated as it drops.

Most causes of poor soil aeration are due to __________ soil drainage. Therefore, poorly drained soils are poorly aerated soils

poor