Introductory Study of Soils

For the Master Gardeners

Wendy Sue Harper, Ph.D.Vegetable and Fruit TA Advisor

Northeast Organic Farming Association of Vermont

www.nofavt.org

What We Will Cover Tonight• Introduction.• Ecological agriculture perspective to

understanding the physical, chemical and biological properties of soil for gardeners.

• Compost basics for home and community gardeners.

Soil: the Foundation of Gardening

WSH

A Plant & Soil Ecosystem Light

Air

Water, etc

Nutrients

pH

CEC

Moisture

Microbes, Earthworms, etc OM = Organic Matter

Temperature

AirTexture

Structure

Pollutants

CEC

Air

MoistureMicrobes

Organic Matter

Structu

re

TexturepH

Pollutants

Nutrients

A Simplified Soil Ecosystem

Soil Fertility isThe ability of a soil to provide a physical,

chemical, and biological environment for the plant that is health sustaining.

This is along term ecosystem based or ecological agriculture perspective!

Seven Principles to Maintain Soil/Water/Plant Resource Base

1. Maintain proper air/water balance2. Maintain soil tilth3. Prevent erosion4. Maintain biological diversity5. Maintain proper SOM levels6. Maintain a proper pH7. Maintain a proper balance of nutrients

(A systems approach means you gotta do them all. Alone each will not build soil fertility.)

A Good Loam Soil:

50% Solids

50% Pores

45% Mineral5% Organic Matter

25% AirBig Pores

25% WaterSmall Pores

So why is this important?

Roots:

1 the plant2 Absorb and3 Exchange4 Store and 5 Transform6 Produce plant 7 Interact with

Support

water nutrients

gasesstarches sugars

nutrients

hormonesmicrobes for disease suppression

An Undisturbed Soil Profile:

Ap

Zone of accumulation

Zone of biological activity

Organic matter

Mix O + A + E = Ap A = topsoil p = plowed or disturbed

Mountain Forest Sandy Soils

• O Organic Matter or A Topsoil Layer

• E Leached Layer• B Accumulations of

Iron, Aluminum and Organic Acids

• C Parent Material

(NRCS/USDA)

Valley Clay Soils

• Ap Topsoil Layer (O Organic Matter tilled in)

• E Leached Layer• B Clay Accumulations • C Parent Material

(NRCS/USDA)

1.Air/Water Balance Depends On:

1 Location on the landscape

2 Soil depth

3 Soil texture(lines=surface area)

4 Soil structure: inside vs. in-between

5 Soil organic matter content: it holds water!

Soil Textural Triangle:

*Loam Soil: The influence of the sand, silt and clay on its physical properties is equal. (Not the quantity or amount, but its influence!)

Here, amounts are equal.

(Brady and Weil, 2002)

Soil Particles That Make Up Texture Feel:

• Sand

• Silt

• Clay

Not apart of Texture:Organic Matter

Gritty

Smooth, like baking flour

Sticky

Greasy

1.Air/Water Balance Depends On:

1 Location on the landscape

2 Soil depth

3 Soil texture(lines=surface area)

4 Soil structure: inside vs. in-between

5 Soil organic matter content: it holds water!

Soil Structure

*Granular, Crumb

*Platy

*Subangular Blocky

Angular Blocky

*Prismatic

Columnar

*Structureless1. Single grained2. Massive

Shape of individual peds

* Note: found in Vermont

You worked your soil when it was too wet?

What did you get?

• You get: CLODS

• It is called: PUDDLING YOUR SOIL

Promote Structure With OM Additions• And Thus:

– Drainage in clay soils (macropores) – Water holding capacity in sandy soils (micropores)

*Cause it Creates the Pores You Ain’t Got!*

Macropore hold air and drain (in-between)Micropores hold water (inside)

OM = Drought Prevention Insurance

Soil Too Dry?Manage to Prevent Water Loss By:

Mulching to conserve moisturePrevent runoffBuild OM content to improve the water holding capacityControl weeds (competition) or used them to your advantagePlant tolerant speciesWater deeply and consistently

Soil Too Wet?Manage for water loss by:

Raised bedsShape of beds

Follow good Management PracticesAdd OM to improve drainage (clays)Don’t work wet soilPlant after soil warms upPlan “wet in early spring” areas for late season crops like tomatoes

Plant tolerant speciesPut in a drainage system to drop the water table

2. Soil Tilth: All the Physical Properties of Soil

Related to Plant Growth

• Including: structure, drainage, aeration, moisture holding capacity, bulk density….

Work a soil when it has dried out enoughAdd OM to improve physical propertiesTreat soil gentlyKeep soil covered

3. Prevent Erosion:Erosion is the process of detachment and

transport by wind or waterPrevent it by:

Make the wind or water less erosive by slowing it down.

Protect the soil from exposure to wind or water.

Build the soils resistance to erosive forces. (Brady and Weil, 2002)

Seven Principles to Maintain Soil/Water/Plant Resource Base

1. Maintain proper air/water balance2. Maintain soil tilth3. Prevent erosion4. Maintain biological diversity5. Maintain proper SOM levels6. Maintain a proper pH7. Maintain a proper balance of nutrients

4. Maintain or Create Biodiversity

& SOIL

DFW

4. Maintain or Create BiodiversityRotate CropsPlant Mixtures of Species

Interplant, Under-sow, Companion Plant, PolycultureAdd CompostMulchPlant Biological or Ecological Islands

Habitat and Food For BeneficialsSelective Weeding

Change Tolerance Levels for PestUse IPM

Cautions?…..

4. Maintain or Create BiodiversityProvide Diverse Food: Organic Matter

Add Organic ResiduesAdd Manure or CompostGrow Cover Crops

Provide Diverse HabitatRotate Crops; Include Cover CropsPlant Mixtures of Species

Interplant, Under-sow, Companion Plant, PolyculturePlant Biological or Ecological Islands; Habitat and Food For Beneficial Organisms

Bio-strips, Flower Strips, Beetle Banks, Strip InsectaryIntercropping, Vegetative Corridors, Hedge Rows or Selective Weeding

Use Mulches; Reduce Tillage and Bare LandChange Tolerance Levels for Pest

Reduce Chemical Inputs: Use Integrated Pest Management

Biological or Ecological Islands

www.sare.org

Syrphid Fly

Lacewings

Parasitic Wasp

www.attra.orgwww.sare.org

www.sare.org

NCSU-IPM

NCSU-IPM

NCSU-IPM

www.sciencemuseum.org.uk

Refugia or Conservation Head Lands

www.sare.org

University of Minnesota Extension

NCSU-IPM

www.sare.org

www.ukagriculture.com

Hedge Rows as Habitat

Wind Shelter Belt

Vegetation Barriers

Vegetative Corridors

Spined Soldier Bug

Praying Mantis

USDA/NRCS/NAC

National Corn Growers Association

Texas A&M University

University of Idaho

www.sare.org

Mulch as Habitat

Ground Beetles

Spiders

DFW

DFW

Beetle Banks: Britain

Ground Beetles and other Predatory Beetles

http://www.orc.govt.nz/

Oregon State University Extension

www.snh.org.uk/

DFW

Intercropping: Living Mulches

Bigeyed BugRover BeetleMinute Pirate Bug

NCSU-IPMwww.omafra.gov.on.ca/

www.dereila.ca

www.sare.org

Time for……..

A. Questions?

B. A Break?

C. A Nap?

D. A Snack? Some Compost Tea?

5. How Can You Get OM Into Your Soils?

Animal Manures

Composts

Cover Crops

Mulches

Peat Moss

Others?

Any Cautions? ……C:N Ratio or Carbon to Nitrogen Ratio

What is Compost?

• Compost is the biological reduction of organic wastes to humus. (Golueke)

MICROBIAL ROT

Scientific American, 1991

Principles of Composting• C:N Ratios

– Recipe• Moisture Balanced with Oxygen

– Recipe– Particle Size

• Temperature – Recipe– Size of pile– Microbes and Macrobes– Time

• Management– Assess Your Level of Interest

C:N Ratio• If hot compost is desired, the ratio preferred is

about 25-30:1, but 20-40:1 is acceptable.• High C Materials: straw, hay, woody materials,

dried corn stalks, paper wastes.– Not are Carbon behaves the same.

• High N Materials: manures, green material, food wastes.

• Start with 1 handful of N wastes to 3 of C wastes.• Cornell’s WWW site for recipe design:

– http://compost.css.cornell.edu/science.html

Moisture Balanced with O2

• If hot compost is desired, a range of 50-60% is preferred, but 40-65% is acceptable.

• Field Test: Compost should feel like a damp sponge. Moist, but you can’t ring water out of it.

• Generally, if the C:N ratio is OK, moisture will be OK too.

• Cornell’s WWW site for recipe design – http://compost.css.cornell.edu/science.html

• Particle size and thus pile porosity are important too!

Temperature• Thermophilic over 105o F

– Recipe more critical– Size is important– Quicker– More management– More labor– Destroys weed seeds– Destroys pathogens– Mainly microorganisms:

Mostly BACTERIA, Some fungi and actinomycetes

– Less disease suppression

• Mesophilic 50-105oF– Recipe less critical– Size is not important– Slower– Less management– Less labor– May not destroy weed

seeds and pathogens – Diversity of both micro

and macro-organisms involved

– More disease suppression

SMB

SMB

SMB

Troubleshooting Hot Compost• Wet and stinky?

• Dry not working?

• No heat when turned?

• Add C materials and turn in sunny weather. Shape to shed water. Break up matting or compaction.

• Add N materials and turn when raining. Shape to hold water.

• Look at material if dark and crumbly with good earth smell, may be curing. No? Check size and consider additions.

Management

VS.

.

Compost a Recipe for Trouble!

Gardener’s Easy Practical Compost Method • In bins or free standing.• Build pile by adding 1 handful

of green/wet stuff for every 3 handfuls of brown/dry stuff, added overtime.

• Add soil/old compost for odor control.

• Turn and rebuild pile in fall, mix in garden cleanup debris.

• Wait 2-3 years before using.• Do not add weeds gone to seed

or plants infected with viruses.

ORGANIC MATERIALS

ORGANIC MATERIALS - Grass, leaves, weeds, etc.

ORGANIC MATERIALS

1-2” manure

Cross Section of Layering in Compost Bin

1-2”

6-8”

SOIL

SOIL

SOIL

SOIL LINE

What Composting Does for You!1. Decrease bulk of the pile (CO2 gas)2. C:N ratio3. Odor 4. Hot composting kills weed seeds & pathogens5. Cool composting provides disease resistance6. Humified (turning to humus) material is a slow

release fertilizer7. Wastes become useful material

gardener’s brown gold

6. Maintain A Proper pH

Which is: pH

7. Maintain A Proper Balance of the Nutrients

How to Know?

Plant Available Major SourceForm of Nutrients

MACRO-NUTRIENTSCarbon CO2 AirOxygen O2 AirHydrogen H2O Water

Nitrogen NO3-, NH4

+ Soil OMPhosphorus H2PO4

-, HPO42- Soil OM

Potassium K+ Soil Minerals

Calcium Ca2+ Soil MineralsMagnesium Mg2+ Soil MineralsSulfur SO4

2-, SO2 (gas) Soil OM, Air

ESSENTIAL ELEMENTS FOR PLANT GROWTH

ESSENTIAL ELEMENTS FOR PLANT GROWTH

MICRO-NUTRIENTSIron Fe2+ Soil Minerals + OMManganese Mn2+ Soil Minerals + OMCopper Cu2+ Soil Minerals + OMZinc Zn2+ Soil Minerals + OMBoron H3BO3 Soil Minerals + OM*Molybdenum MoO4

2- Soil Minerals* + OMChlorine Cl- Soil Minerals + Rain*Cobalt Co2+ Soil Minerals + OMNickel Ni2+ Soil Minerals + OM

OTHERS??Sodium, Selenium, Silica, Vanadium, Iodine, Fluorine???

Plant Available Major SourceForm of Nutrients

Soil Solution:The Thin Skins of Water that Coat

Everything.Roo

t Hair

CationExchangeCapacity +

++

+++ We are positive!

Cations

K+ Mg2+ Ca2+ H+ Al3+

pH near neutral Acid pH

NO3-

The pH of things in our lives.

* Distilled water or rain water = pH 5.6

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

pH Acid

Basic

NeutralSoils

Lemons

Lye

AmmoniaMilk of Magnesia

SeawaterBicarb of Soda

Vinegar, Grapefruit, Wine

Grass silageTomatoesBeerBoric Acid

Human bloodManure

Cows milkDistilled water

H+ + OH- = HOH = H2OAcid + Base = Water

pH Effects on Nutrient Availability

pH P

refe

renc

es fo

r Sel

ecte

d Pl

ants

(Foth, 1992)

DOYOU

KNOWWhat’sIn Your

Dirt?

pH??

Heavy Metals??

N-P-K??

% OM??

Micronutrients??

http:/

/pss.u

vm.ed

u/ag_

testin

g/form

s.htm

l

Soil Test Report

• Soil Test Results• Recommendation

– Limestone– Nitrogen– Phosphorus– Potassium

• Management Info• Who to call

On Back

• Interpretation of soil test results to help you figure out what all this soil test information means.

Useful Soil Resources• Start with the Soil: The Organic Gardener’s Guide to

Improving Soil for Higher yields, More Beautiful Flowers, and a Healthy Easy Care Garden by Grace Gershuny. Rodale Press. 1993.

• The Nature and Properties of Soils by NyleC. Brady and Ray R. Weil. Prentice Hall. 2002.

http://pss.uvm.edu/ag_testing/forms.html

Useful Compost Resources• The Rodale Book of Composting

by Deborah L. Martin & Grace Gershuny. Rodale Press. 1992.

• On-Farm Composting Handbook by Robert Rynk. NRAES-54. 1992.

• Cornell’s WWW site:– http://compost.css.cornell.edu/Composting_homepage.html– http://compost.css.cornell.edu/science.html

Biological Slide References• DFW: The Decomposer Food Web: Ecology

of organisms of compost and soil litter byDr. Daniel Dindal, Professor Emertius, Soil Ecologist, SUNY-Syracuse

• SMB: Soil Microbiology and Biochemistry from Soil Science Society of America

• WSH: Wendy Sue Harper, Ph.D.

More Questions on Soils or Compost?

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The End