Soils, Fertilizers
and Composting
William T. Hlubik
County Agricultural Agent, Professor
Definition
• Soil
– a natural body on the surface of the earth in
which plants grow; comprised of mineral and
organic materials and living organisms
Soil Profile
• Layers in the soil are
called „horizons‟
• The upper layer is
called „topsoil‟
• The middle layer is
called the „subsoil‟
• The parent material or
bedrock is found
below these layers
Topsoil
Subsoil
Parent Material
Soil Profile
Soils Map of New Jersey
• This map shows the major soil series of NJ
• Note the strong association between the bedrock geology and the soil formed
• Soils differ across geographical regions due to many other factors, not just geology
Soil Forming Factors
• In nature, the five soil-forming factors are:
– Parent material
– Climate
– Living organisms
– Landscape position
– Time
Soil Survey Map
Soils Maps – Soil Survey
• „Soil Survey‟
– Printed copies of county-based soil surveys
may be available from local Soil Conservation
District offices
– Web-based copies may be found at:
http://websoilsurvey.nrcs.usda.gov/app/
Soil Characteristics
• Physical characteristics
• Biological characteristics
• Chemical characteristics
Physical Characteristics
• Soils are comprised of:
– Solids
• Mineral component
• Organic component
– Liquids
• water
– Gases
• ex. O2, CO2
45-50%
0-5%
Physical Characteristics - Texture
• Texture
– Fineness or coarseness of the soil
– Refers to the relative amounts of different
sized particles in the soil
– There are 3 soil particles, classified by size,
that determine the soil texture
Physical Characteristics - Texture
• Sand
– 2 mm to 0.05 mm in diameter
• Silt
– 0.05 mm to 0.002 mm in diameter
• Clay
– 0.002 mm or less in diameter
Sand
Silt
Clay
12 Textural Classes
Sand
2 mm 1.0 mm 0.5 mm 0.25 mm 0.125 mm 0.05 mm
• Clay– Kaolinite type
– Surface area =• 1500 to 6100
ft2 per ounce of this clay type
• 0.6 to 2.4 lbs of this clay would provide the surface area of a football field
Feel Method
Rough = sand
Slick, greasy when wet =
clay
Smooth when dry = silt
Falls apart = sand
Stays together, extend
far beyond fingers =
clay
Some form but
crumbles = silt
Ribbon Method
Physical Characteristics - Tilth
• Tilth or structure is affected by several
factors, including:
– Organic matter, limestone, biological activity
• All increase aggregation or flocculation of particles
– Sodium
• Decreases aggregation or dispersion of particles
• Tilth is primarily a „by-product‟ of biological
activity
Physical Characteristics - Tilth
Physical Characteristics - Tilth
Physical Characteristics - Tilth
• Aggregate stability
– Ability of soil particles to continue to be held in
a single mass or cluster
Physical Characteristics - Tilth
Biological Characteristics
• In one teaspoon of “healthy” soil there should be:– 600 million bacteria
– three miles of fungal hyphae
– 10,000 protozoa
– 20 to 30 beneficial nematodes in a teaspoon of soil
Dr. Elaine R. Ingham, Soil Food Web
Biological Characteristics
• Microorganisms play important roles in:
– Organic matter creation and turnover
– Nutrient transfer and availability
– Disease transmission and prevention
Biological Characteristics -
Organic Matter
• The fraction of the soil that includes plant
or animal residues at various stages of
decomposition
• Formation:
– Residues added to the soil are broken down
by microorganisms and macroorganisms into
their basic components
• Proteins, organic acids, minerals, etc.
Biological Characteristics -
Organic Matter
– The organic materials are a food source for
these organisms
– The substances exuded are “glues” that help
to hold soil particles together
Biological Characteristics -
Organic Matter
• Benefits:
– Enhances biological activity
– Improves tilth and structure
– Increases porosity and infiltration
– Reduces crusting and erosion
– Increases water holding capacity
– Improves cation exchange (nutrient holding
and release)
Biological Characteristics –Nutrient Availability, Transformation
Biological Characteristics -
Disease Prevention
• Higher levels of
biological activity and
diversity often lead to
higher levels of
suppression through
various mechanisms
– Pythium and
Phytophthora
– Mycorrhizal fungi
– Springtails and mites
Trichoderma harzianum
Rhizoctonia solani
Biological Characteristics
Physical Characteristics – Water
• Movement in Soil
– Infiltration• Downward movement of water into the soil surface
– Percolation• Downward movement of water through the soil
Physical Characteristics –
Water Movement in Soil
• Infiltration
– Movement of water into the soil surface
sand silt clay
feet spread
Physical Characteristics –
Water Holding Capacity
• Water Holding Capacity
– Soil‟s ability to hold internal moisture
– Can be increased by raising organic matter levels
sand < silt < clay
• Drainage
– the duration and frequency with which water
is held in the soil
Physical Characteristics - Drainage
• Drainage affects
– Soil drying or moisture holding
– Air flow or gas exchange
– Selection of turf grass species
Physical Characteristics - Drainage
Physical Characteristics - Drainage
• Do a mini „perc test‟ or percolation test to
determine the internal drainage
1. Dig a 12 inch deep hole
2. Fill hole with water
3. Let all of water drain out of hole
4. Fill hole again and measure time for
water to drain out
Physical Characteristics - Drainage
• Evaluate the results. If all of the water
drains out of the hole in:
– 15-30 minutes or less = well drained soil
– 30-45 minutes = moderately drained soil
– Greater than 45 minutes = poorly drained soil
Physical Characteristics - Drainage
• Based on internal and surface drainage,
do the following:
– Choose plant materials appropriate for the
site
– Improve water drainage and percolation
– Irrigate when necessary
– Use mulches to conserve moisture
Physical Characteristics –
Compaction
• Compaction
– Physical pressure due to
weight on soil squeezes
out the air space, making
the soil more dense
• Bulk Density
– The weight of dry soil per
unit volume including air
space
Physical Characteristics –
Compaction
• Reducing Compaction
– Mechanical aeration
– Tillage
– Organic matter
– Chemically
– Prevention
Physical Characteristics –
Compaction
Images from Turf North, Nov 2005
Physical Characteristics –
Compaction
Chemical Characteristics
• Nutrients
– Essential chemical elements required for
plants to grow
Chemical Characteristics
• Macronutrients:
– Nitrogen (N)
– Phosphorus (P)
– Potassium (K)
– Calcium (Ca)
– Magnesium (Mg)
– Sulfur (S)
• Micronutrients
– Iron (Fe)
– Copper (Cu)
– Boron (B)
– Chlorine (Cl)
– Manganese (Mn)
– Zinc (Zn)
– Molybdenum (Mo)
Chemical Characteristics –
Plant Nutrients
Chemical Characteristics –
Plant Nutrients
Nutrient Sources
• Nitrogen often comes from fertilizer application and from the air (legumes N from atmosphere)
• Phosphorus often comes from fertilizer, bone meal, and superphosphate.
• Potassium is supplied to plants by soil minerals, organic materials, and fertilizer.
• Sources of calcium are calcitic and dolomitic limestone, gypsum, and superphosphate.
• Magnesian and dolomitic limestones, soil minerals, organic material, and fertilizers are sources of magnesium for plants.
• Sulfur may be supplied to the soil from rainwater. It is also added in some fertilizers as an impurity, especially the lower grade fertilizers. The use of gypsum also increases soil sulfur levels.
Chemical Characteristics - pH
• pH
– A measure of the soil‟s
acidity or alkalinity
– pH scale is from 0 to 14
• Vinegar = 2.2
• Cow‟s milk = 6.4
• Lye = 13.0
• Plants have specific
soil pH requirements
for optimum growth
Chemical Characteristics - pH
• Ericacious or „acid loving‟ plants
– pH 4.5 to 5.5
– Azaleas, rhododenrons, hollies
• Near neutral
– pH 6.2 to 6.8
– Most crops, turf, landscape plants
• Alkaline
– pH 7.2 +
– Bayberry, Douglass fir
Soil pH
• Soil pH
– A measurement of the concentration of active
acidity in the soil
– Also called soil “water pH”
Chemical Characteristics - pH
• To reduce acidity
– Agricultural limestone
• A material containing the carbonates, oxides and
hydroxides of calcium and/or magnesium
CCE value: calcium carbonate equivalent
Can be used to calculate the amount of this material
needed to effect a desired pH change
Limestone Rate Based on Soil pH
and Soil Texture
Pounds of Limestone/1000 ft2 to Raise pH to Desired Level
Change in Soil Texture
Soil pH Sand Loam Clay Loam
4.0 – 6.5
4.5 – 6.5
5.0 – 6.5
5.5 – 6.5
6.0 – 6.5
60
50
40
28
14
161
133
105
78
41
230
193
152
106
55
Selection of Liming Material
• Liming recommendation based on:
– Amount of pH adjustment needed
– Current calcium and magnesium levels
Lime Selection/Soil Test Level
• Dolomitic lime (high Mg)
– Use when soil test Mg level is low relative to Ca
• Calcitic lime (high Ca)
– Use when soil test Ca level is low relative to Mg
• Gypsum (calcium sulfate)
– Use when soil pH is high but Ca is needed
Selection of Liming Material
• Selection of material – particle size
– Pulverized smallest
– Ground
– Pelletized
– Granular largest
Chemical Characteristics - pH
• To increase acidity
– Sulfur (S)
• elemental sulfur
• iron sulfate
• aluminum sulfate
Sulfur Needed to Increase Soil
Acidity to pH 6.5
Pounds of Sulfur/1000 ft2 to Raise pH to Desired Level
Change in Soil Texture
Soil pH Sand Loam Clay Loam
8.5 – 6.5
8.0 – 6.5
7.5 – 6.5
7.0 – 6.5
46
28
12
2.5
58
35
18
3.5
70
46
23
7.0
Step 1: Soil Testing
• Soil testing should be completed through a
certified soil testing laboratory
– Soil testing services are available from many
Land Grant universities and colleges
– Soil testing kit includes sampling instructions,
data collection form, and mail-in envelope
– Cost is approximately $15 per sample
– Soil testing kits are available through your
local Cooperative Extension office
Step 1: Soil Testing
Step 1: Soil Testing
• Best results are obtained from properly
collected sample
– Take multiple sub-samples from representative
areas
– Sample to a depth of 6 to 8 inches
– Mix the sub-samples together and remove
about 1 cup of soil for sending to the laboratory
Step 1: Soil Testing
Take multiple, randomly
selected sub-samples from
the area to be tested
6-8”
Step 1: Soil Testing
• Best results are obtained from properly
collected sample
– Remove any stones, roots and other materials
– Air dry the sample before sending it to the
laboratory
Step 1: Soil Testing
• Complete the soil testing questionnaire
– Indicate current and intended use of the
site
Step 1: Soil Testing
– Indicate whether a new seeding/planting or
established planting
• Send the soil sample and questionnaire
to the laboratory
• Results are usually returned in 1-2
weeks
SAMPLE
Step 2: Evaluate and Implement
• Review and interpret the soil test results
– Existing pH level
• Numerical value
• Verbal description
– Existing nutrient levels and corresponding
fertility category
• Very low, low or medium = Below optimum
• High = Optimum
• Very high = Above optimum
Determines
amount of lime
Selection of
liming
materials
Need for
phosphorus
and potassium
fertilizer
Need for
micronutrient
fertilizer
Questions ?
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