2013

Master Gardener Trainee

Soils Class

JOHN ALLISONCharles CityNew KentAgricultural and Natural Resources Extension Agent

Who is Virginia Cooperative Extension

Network of experts

and educators who provide information, education, and tools the public can use every day to improve life.

What Virginia Cooperative Extension Does

Brings the

research and resources of Virginia's land-grant universities, Virginia Tech and Virginia State to the public.

ANR Program Area Help sustain the profitability of

agricultural and forestry production by bringing current technology and management practices to the agriculture industry.

Enhance and protect the quality of our land and water resources.

Diagnose soil and crop problems for growers.

Help home owners answer lawn, garden, and landscape questions.

Connect the public with VT and VSU research.

What I Do

SoilsINFILTRATIONPERCOLATION

DOMESTICand

WILD

ATMOSPHERICHUMAN

FORESTPRAIRIEFARMS

SUBURBAN

Soils

Soils vary greatly across landscapes by Physical

Properties such as:

• Organic Matter Content• Color• Density• Texture

• Structure• Depth• Drainage • Porosity

Chemical Properties such as: pH and Nutrient Availability

Soil Physical Properties

Soil Physical Properties

OM mostly in surface horizon

50 percent solids

50 percent pore space

Soil Density

Particle Density – The density of each sand, silt, and clay particle.

Bulk Density – The density of the volume containing sand, silt, and clay particles.

PARTICLE DENSITY

100 % SOLIDS

WEIGHT 2.65 GRAMS

VOLUME 1cm3

BULK DENSITY

50 % SOLIDS, 50 % PORES

WEIGHT 1.5 GRAMS

VOLUME 1cm3

Soil Texture

Solids Made up of sand,

silt, and clay. The mixture of these

components is called Soil Texture.

Soil Texture

Textural Triangle

Soil Texture

Soil Ribbons

Soil Structure

Solids Made up of sand,

silt, and clay. The orientation of

these components is called Soil Structure.

Granular Structure Prismatic Structure

Blocky StructurePlaty Structure

Columnar Structure

Soil Porosity

SOIL PORES are the spaces between soil structural units. They are also made by roots, burrowing insects and animals. They are inhabited by microorganisms and roots. They contain water and air. Their volume is

determined by texture, structure, and bulk density.

Soil Water

SATURATION All pores are filled with

water. All air is excluded. Anerobic conditions

exist. Plants and animals

suffocate. Microbes reduce iron

oxides to obtain oxygen.

Soil Water

FIELD CAPACITY Two thirds of the

pores are filled with water.

Air in one third of pores.

Areobic conditions exist.

Plants, animals, and microbes thrive.

Soil Water

AVAILABLE WATER Water content

between Field Capacity and Wilting Point.

Two thirds to one third of the pores are filled with water.

Soil Water

WILTING POINT Less than one third

of pores filled with water.

Water is adsorbed too tightly to soil particles to be available to plants.

Plants, animals, and microbes die.

Soil Color Iron Oxides coat

every soil particle. Where Organic

Matter does not mask the rust, soils exhibit rusty colors.

Saturated conditions cause microbes to use oxygen from the oxide compounds leaving the Iron soluble in soil water.

RUSTY IRON

Soil Color

REDYELLOW

Soil Color

BROWN GRAY

Organic Matter

PARENT MATERIAL

Actinomycetes are bacteria critical in decomposition of organic matter and humus formation. Their presence is responsible for the sweet "earthy" aroma associated with a good healthy soil.

ActinomycetesMycorrhizaBacteriaFungi

Organic Matter

Symbiotic association between a fungus (Myco) and the roots (rhiza) of the plants.

The plant gains increased exploration of the soil (rhizo sphere) with the intricate net of hyphae that increases the uptake of water and nutrients from the soil.

The fungus uses the carbon provided by the plant for its physiological functions, growth and development.

Mycorrhiza

Organic Matter

Soils with sufficient OM typically have an increased capacityto hold water, requireless fertilizer, and

havehigher yields than

soilsWith little or no OM.

Organic Matter

Soil Horizonation

Soil Horizonation

O Horizon

A Horizon

E Horizon

B Horizon

C Horizon

R Horizon

Soil Horizonation

A Horizon: Top Soil; Zone of Organic Matter accumulation; Horizon with the most biological activity.

B Horizon: Subsoil; Zone of clay accumulation; Horizon with the most water holding capacity.

Soil Horizonation C Horizon is the Parent Material, not soil. PARENT MATERIAL is the geologic material that

soil develops from. It may be:rock that has decomposed in place.sand, silt, and/or clay that has been

deposited by wind, water, or ice. The character and chemical composition of the

parent material plays an important role in determining soil properties.

Soil Horizonation

Horizons are defined by physical and chemical parameters such as:

• Acidity• Nutrient Availability• Organic Matter

Content• Texture• Structure • Density• Porosity• Color• Mineral Content• Drainage

Soil Drainage

Excessively Drained Well Drained Moderately Well Drained Somewhat Poorly Drained Poorly Drained

Soil Drainage

Excessively Drained

Sandy throughout,droughty.

Soil Drainage

Well Drained

No water tablein the root zone.

Soil DrainageModerately Well Drained

Any texture; soil profilehas a well drainedhorizon immediatelybelow the top soilfollowed by a horizonaffected by a SHWT dominated by brightcolors.

Soil Drainage

Somewhat Poorly Drained

Any texture; soil profile hasa horizon affected by aSHWT immediately beneaththe A that is dominated bybright colors, immediatelyfollowed by a horizon affected by a SHWT and dominated by gray colors.

Soil Drainage

Poorly Drained

Any texture; soilprofile is

affectedby a SHWTthroughout. Soilis dominated bygray colors.

Soil Depth

Very Shallow Shallow Moderately Deep Deep Very Deep

Soil Depth

VERY SHALLOW SOILS

10 inches

7 inches

Soil profile thickness is

10 inches or less above the Parent Material.

Soil Depth

14 inches

16 inches

Soil profile thickness

is 10 to 20 inches over Parent Material.

SHALLOW SOILS

Soil Depth

36 inches

24 inches

MODERATELY DEEP SOILS

Soil profile Thickness is

20 to 40 inches over Parent Material.

Soil Depth

44 inches55 inches

DEEP SOILS

Soil profile thickness is 40 to 60 inches over Parent Material.

45 inches

Soil Depth

VERY DEEP SOILS

Soil profile thickness is

greater than 60 inches over Parent Material.

Soil FormationFive Soil Forming Factors

Soil Formation

CLIMATEFreeze - ThawWetting -

Drying

Soil Formation

ORGANISMS

Soil Formation RELIEF

Soil Formation

PARENT MATERIAL

River Deposits

Residual Weathering

CoastalPlain

Sediments

Soil Formation

TIME

Soil Erosion

WIND EROSION WATER EROSION

SALTATION LIQUID SUSPENSION

Soil Erosion

Erosion Controls prevent and/or reduce soil erosion.

Soil Erosion

Sediment Control captures

and contains eroded soil.

Soil ErosionSuburban Soil Erosion and Sediment Control

Practices

HydroSeeding

Rock Dam

Straw Wattles

Sediment Fence

Soil ErosionAgricultural Soil Erosion and Sediment Control

Practices

Cattle Exclusion

Cover Crops No-Till

Strip Cropping

Soil Fertility and FertilizersSoil Supplied Nutrients

Macronutrients: P, K, S, Ca, Mg Micronutrients: B, S, Fe, Cu, Cl, Mn, Mo, Zn

Atmosphere Supplied NutrientsMacronutrients: C, H, O, N

Mos

t P

rod

uct

ive

Soi

ls

Bas

icit

yA

cid

ity

Strong

Medium

Slight

Slight

Moderate

Medium

Strong

Very Strong

9.0

8.0

7.0

6.0

5.0

4.0

Neutrality

pH value defines activity of Hydrogen cation

pH = - log[H+]

Soil pH

pH and Fertilizer Use

Soil acidity can be directly toxic to plants but more often it reduces the ability of the plant to take up nutrients.

pH Importance

Low pH = Mo Deficiency

High pH = Mn Deficiency

Types of Soil Acidity

Exchangeable or Reserve Acidity

Active Acidity• H+ cation in soil solution measured as pH.

• Very small amount of Total Acidity.

• Acidity that affects plant growth.

• Various Al compounds react with water resulting in free

H+ cations in solution.

• 1,000 to 100,000 times greater than active acidity.

Liming the Soil

Water pH = Active pH

Buffer pH • Used for lime recommendations

• Measures Active and Reserve Acidity (Total Acidity)

How Lime WorksA Ca2+ ion from the lime replaces two H+

ions on the cation exchange complex.

The H+ ions combine with OH- to form water.

Soil pH increases because the acidity source (H+) has been

reduced.

How Lime Works

Ca2+ clay- - -

--

-H+

H+

clay---

- ----

---

CaCO3 (Lime)

+ H2O + CO2

Water Carbon Dioxide

Ca++ + HCO3- + OH-

+

Lime 2 to 6 months ahead of planting to allow sufficient time for soil reaction to take place.

Particle Size and Chemical Composition of Liming Materials

PARTICLE SIZE or mesh influences the speed at which the material dissolves and reacts with the Hydrogen ion in solution.

CHEMICAL COMPOSITION determines a liming material’s acid-neutralizing value.

Pure calcium carbonate, CaCO3, is the standard for all liming materials and has an acid neutralizing value

of 100 percent. When a liming material is

evaluated, it is compared to calcium carbonate, and its neutralizing value is called the Calcium Carbonate Equivalent, CCE.

200 mesh

20 mesh

10 mesh

100 mesh

1/8 inch

3/16 inch

1/4 inch

1/2 inch

3/4 inch

IPNI

How Quickly Lime Works

Lime Application• Lime recommendation should last two to three years. After that retest the soil.

• A liming material with a higher CCE value will have a greater effectiveness than one with a lower CCE value.

• Lime can be applied any time of

the year, but late summer and fall applications are preferred.

Fertilizers

Liebig’s Law of the Minimum

Fertilize to prevent yield loss.

Focus $ on correct nutrient.

Do not over-apply• Agronomic• Environmental• Waste Money

Lab Test ResultsShows the relative availability of nutrientsas a rating:

• L=Low - Plants almost always respond to fertilizer. • M=Medium - Plants sometimes respond to fertilizer. A moderate amount of fertilizer is typically recommended to maintain fertility.• H=High to VH=Very High - Plants usually do

not respond to fertilizer.

Fertilizer Recommendations

• Fertilizer recommendations may be used for the same

crop for two to three years then retest the soil.

• When soil tests are High or Very High, retest the following year to determine if fertilizer will be needed.

Fertilizer Recommendations

No soil test is performed for nitrogen because this element is too mobile in the soil for laboratory results to be useful.

Nitrogen fertilizer recommendations are based on the crop/plant to be grown, the previous crop, and yield potential.

Fertilizer Analysis

Complete AnalysisFirst Number:

20 percent Nitrogen (N)

Second Number:

10 percent Phosphorus (P)

Third Number:

20 percent Potassium (K)

Fertilizer AnalysisComplete Analysis

A 50 Pound Bag Would Be:

First Number:

10 pounds Nitrogen (N)

Second Number:

5 pounds Phosphorus (P)

Third Number:

10 pounds Potassium (K)

Fertilizer AnalysisIncomplete Analysis

A 50 Pound Bag Would Be:

First Number:

9 pounds Nitrogen (N)

Second Number:

23 pounds Phosphorus (P)

Third Number:

0 pounds Potassium (K)

Slow-Release Fertilizer (N)Beneath the guaranteed analysis one can find a statement to the effect that X percent of the nitrogen (expressed as a percentage by weight of the package contents) is in slow-release form. The words water insoluble, slowly available or slowly available soluble nitrogen also indicate slow-release sources of nitrogen.

If, for example if a 50 pound bag of 10-10-10 fertilizer

says it contains 5 percent slow-release nitrogen, divide

the 5 percent by the total percent N in the product and

multiply by 100 to get the percentage of nitrogen that

is in slow-release form. In this example it is 5/50 x 100 = 50 percent.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Cottonseed meal is the byproduct remaining after cotton is ginned and the

seeds crushed and the oil extracted.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Blood meal is a dry, inert powder made from blood used as a high-nitrogen fertilizer.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Bone meal is a mixture of finely and coarsely ground animal bones and slaughter-house waste

products. It is a slow-release phosphorus fertilizer.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Common forms of animal manure include dry farmyard manure and liquid farm slurry. Manure may contain plant material such as straw used as bedding for animals to absorb feces and urine.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Green Manures are crops grown for the express purpose of plowing them in, thus increasing fertility through the incorporation of nutrients and organic matter into the soil. Legumes such as clover are often used for this, as they fix nitrogen.

Organic Fertilizers

Cottonseed Meal Blood Meal Bone Meal Manure Bio-Solids

Since the 1920s, the City of Milwaukee Sewerage Commission has been converting Biosolids into Milorganite, a heat-treated, pelletized, organic fertilizer made from processed wastewater municipal treatment plant organic waste.

Nutrient Summary

General Rule of Thumb

N is for leafy top growth. P is for root and fruit production K is for cold hardiness and disease resistance

Soil Sampling

Divide the landscape into areas of unique

use.Examples are

vegetablegardens, lawns, flower beds, and areas wherelandscape plants are growing. Sample and box the soil from each area separately.

Soil Sampling

To collect soil samplesuse a clean stainless steel or chrome platedsoil probe, hand

garden trowel, shovel or

spade.

Soil Sampling Make up the composite

soil sample by taking 10 or more sub-samples from different locations within each area. Use a zigzag pattern to capture the variability of the area. Mix soil samples in a clean plastic bucket and place in a box to be sent to the VT soils testing lab.

Virginia TechSoil Testing Lab 45 Smyth Hall Blacksburg, VA 24061

At The LabSoil Extracts Measure:

• What is considered “plant available”.• DOES NOT extract total nutrients• Based on calibration curves from many years of

research• Each soil test is different and must be compared

to the correct recommendations curves.

• For Instance: You cannot use a Mehlich-1 curve

for Mehlich-3 extract data.

Acknowledgements

Dr. Mark S. ReiterSoils and Nutrient Management SpecialistEastern Shore AREC

Contact InformationJohn AllisonANR Extension Agent

10900 Courthouse Road                          11809 New Kent HighwaySuite 240            Suite 1P.O. Box 55                                              P.O. Box 205       Charles City, VA 23030                            New Kent, VA 23124john.allison@vt.edu                                  john.allison@vt.eduMain Office: (804) 652-4743                     Main Office: 804-966-9645   Fax: (804) 829-9820                                 Fax: 804-966-5013