soils, fertilizers and composting...soils, fertilizers and composting william t. hlubik county...

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 ?