Mrs. Long
Horticulture I
Fall 2013
 Soil is the
unconsolidated
cover on the
surface of the
earth.
 Soil is made up of
mineral particles,
organic particles,
air and water.
 Soil is capable of
supporting plant
growth.
About ½ of the
soil volume is
solid particles
Mineral
Matter
45%
Organic
Matter
5%
Soil
Air
25%
Soil
Water
25%
About ½ of the
soil volume is
pore space
 Anchor plant roots
 Supply water to plant roots
 Provide air for plant roots
 Furnish nutrients for plant
growth
 Release water with low levels of
nutrients
 Organic matter is the glue that
holds the aggregates together
 Large pores (spaces) between
aggregates are filled with air in
a moist soil.
 Small pores are filled with
1/10 inch
water in a moist soil. Even
smaller pores inside the
aggregates (not shown) are also
filled with water.
 Sand
 Loose
 Silty
 Granular
 Clayey
 Platy or
Blocky
 The mineral part of soil consists of sand, silt, and
clay particles
1/100 in
Sand
0.1 – 0.002 in
2 – 0.05 mm
Silt
0.002 – 0.0001 in
0.05 - 0.002 mm
Clay
Less than 0.0001 in
Less than 0.002 mm
 Sand – Largest particles – low moisture holding capacity
 Silt – Medium particles – good moisture holding
 Clay – Smallest particles – Hold a lot of water
 Loam – equal parts sand, silt, clay – ideal texture!
 Parent Material
 Mechanical weathering – breaks down rock into smaller
pieces without changing soil chemistry
 Chemical weathering – breaks down rocks into smaller
pieces by chemical reaction
 Biological weathering – results from activities of living
organisms
 Bring a small soil sample from your yard at home.
 Make sure its clean.
 Bring in a full quart-sized ziploc bag full of soil
 YOUR NAME has to be on it!!
5.02 Discuss the soil profile and soil sampling for surface and subsurface
layers.
10/31/12
 Soil Particle Size Lab (Part I)
 Take your soil sample (1 per group)
 Place a cup full of soil into a jar
 Fill the jar to the top with water and tighten the lid.
 Shake for 3 minutes.
 Set to side (labeled) until tomorrow!
 Soil layers are called
horizons.
 Layers parallel to earth’s
surface
 Defined usually by
color, texture and
physical features.
 The O horizon contain
Organic matter
 Uppermost dark Colored
 Most fertile
 Made of leaves, twigs,
waste, decaying matter
 Topsoil
 Porous mix of humus
 Just below the O
 Home to earthworms
and microorganisms
 Brown in color
 Subsoil
 Clayey with high mineral
content
 Brownish red
 Receives a lot of leached
material
 Parent material
 Clumps of unweathered
rocks
 Bedrock
 Cannot be dug by hand
 Very few roots can
penetrate
 Determines levels of
fertility in soil
 Use this information to
make accurate fertilizer
recommendations for
growing plants
 A soil test shows
deficiencies, excesses
and imbalances can be
avoided.
 Kits are available at local
garden centers
 Submit samples to NC
Dept of Agriculture and
Consumer Service
Agronomic Division
 https://www.youtube.co
m/watch?v=vb5wtgaKGU
s
 Information from a soil test
will help you select the proper
liming and fertilization
program to obtain optimal
growth of lawn, garden and
ornamental plants.
 Create a visual grid of the
area to be planted.
 5-10 subsamples from
the site
 Sample before the
growing season
 Use a stainless steel soil-
sampling probe
 Take the surface sample
to tillage depth
 4 inches for lawns
 6-8 inches for crops
 Mix soil samples
together.
 Remove any:
 Grass
 Rocks
 Any other material
 SOIL ONLY!!
 Place soil samples in a
box
 Get one from County
Extension
 Also need Soil Sample
Information Sheet
 Send soil tests to Raleigh
 Free for residents
 NCDA&CS Agronomic Services Division
Mailing Address: 1040 Mail Service Center, Raleigh NC 27699-1040
Physical Address: 4300 Reedy Creek Road, Raleigh NC 27607-6465
Phone: (919) 733-2655; FAX: (919) 733-2837
 Perform the:
 Soil Testing Webquest (Activity 5.02.02)
 Making “Dirt”
 Bedrock at bottom - R
 Parent material - C
 Subsoil - B
 Topsoil - A
 Organic matter – O
Types of Horticulture Soils
 Organic
 Partially decomposed
material from Swamps
 Holds moisture
 Inorganic
 Natural volcanic
material
 Helps with soil aeration
and water holding
capacity
Organic Matter
Compost
 Dead plant or animal
 Decayed organic matter
tissue
 Contains Carbon!
 Used for soil
conditioning
 Fertilizer
 Organic
 Larger matter
 Promotes drainage
 Mainly for trees and
shrubs
 Organic
 Dehydrated bog plants
 Holds moisture
 Very acidic
 Hanging baskets
Advantages
Disadvantages
 Sterile
 Expensive
 pH is neutral
 Light weight
 Disease and weed free
 Good for starting plants
 Easy to mix
 Improves plant
uniformity
 The process of
growing plants
without soil.
 No soil & problems associated with soil.
 Easy to control nutrient content of plants.
 Plant support must be provided with strings, wires, or




stakes.
Water quality must be high.
Diseases spread through water.
More moisture or humidity in air to cause favorable
environment for disease organisms.
More expensive.
 Soil pH is a measure of the acidity or alkalinity of
soils
 pH ranges from 0-14, 7 being neutral
 Ideal pH is 5.5-7.5
Lime
Calcium/Sulfur
 Raises the soil pH
 Lowers the soil pH
 Give names to soils
combos
 Clay
 Sandy Clay
 Silty Clay
 Clay Loam
 Sandy Clay Loam
 Silty Clay Loam
 Loam
 Sandy Loam
 Silty Loam
 Sand
 Loamy Sand
 Silt
 Permability
 Rate at which water moves through the soil
 Water Holding Capacity
 Ability of soil to hold water for plant use
 Porosity
 Amount of air space between particles