Mary Bianchi University of California Cooperative Extension

SOILS FOR THE GARDENER

Mary BianchiUniversity of California Cooperative Extension

Our agenda for today Basic soil principles The things we add to our soils

Amendments Mulches Compost Fertilizers

Soils for the Gardener Why are Soils Important to Sustainability?

Landscapes with local conditions in mind Optimal growing conditions, or The right plant in the right place!

Landscapes that conserve and protect Water, air and soil quality Energy

Landscapes that send less to the landfill Composting, recycling, water and fertilizer conservation

Soils for the Gardener

The Soil Habitat Webster’s Dictionary

definition of habitat: the site where a plant

normally lives and grows

Copyright 1999 Oregon State University

Soils for the Gardener

Soil Profile

What will the roots experience

in this soil?

Photo by Jim Fortner, USDA NRCS

Soils for the Gardener What would a root need to thrive in

the soil habitat? Space Air Water Food Diversity!!

Soils for the Gardener What would a root need to survive

in the soil habitat? Space

Do these roots need

different spaces?Copyright 1999 Oregon State University

Soils for the Gardener

Courtesy of Southern Nevada Water Authority

Roots Under Perfect Growing Conditions

Soils for the Gardener What would a root need to

survive in the soil habitat?

SpaceThink vertically!

How can you give a root more room to grow vertically?

Soils for the Gardener What would a root need to survive

in the soil habitat?

Air Respiration

Soils for the Gardener

Pore space

Pore space is the conveyor of oxygen, water, dissolved nutrients and provider of space for root growth

Soil texture and soil structure influence the amount of pore space in the soil

Soil texture is the percentage of Sand Silt Clay

Soils for the Gardener

Can you change soil texture?

Remember soil texture is the percentage of Sand Silt Clay

Soils for the Gardener

Courtesy of Soil Science Society of America

Soil Textural Triangle

% clay

% silt

% sand

100% clay

100% sand 100% silt

Soils for the Gardener

Courtesy of Soil Science Society of America

Soil Textural Triangle

clay

siltsand

Soils for the Gardener

Courtesy of Soil Science Society of America

Soil Textural Triangle

Soils for the Gardener

Courtesy of Soil Science Society of America

Soil Textural Triangle

Sandy loam

Soils for the Gardener

Courtesy of Soil Science Society of America

Soil Textural Triangle

Loam

50-70% clay 30-50% silt

25-50% sand

Estimating Soil Texture

Estimating Soil Texture

Estimating Soil Texture

From Colorado State Master Gardener Fact Sheet #214

Soil texture affects pore space

Sandy soils have fewer, larger pore spaces

Clay soils have more, smaller pore spaces

Advantages? Disadvantages?

WATER MOVEMENT IN SOILS

Water infiltrates in Hagerstown silt loam – Penn State Soils 101

Wetting front advances through the Hagerstown and a bit into the high clay soil to the right in this photograph.

The wetting front has reached the coarse sand. What is happening here?

Another view as the wetting front reaches the boundary between the Leetonia and the coarse sand.

Look at what is happening at the Leetonia/coarse sand boundary!

Finally the water breaks through the coarse sand layer.

The water has made it through the coarse sand and gravel and is advancing into the Hublersburg.

A good final shot of the wetting front.

Soils for the Gardener Soil structure

Soil structure refers to form of aggregates

Except for sands, soil particles don’t exist as single particles but as aggregates

Soil structure

Soil structure refers to form of aggregates

Except for sands, soil particles don’t exist as single particles but as aggregates

Structure and diversity go hand in hand

Organic matter in the soil affects soil structure

Humus, plant and microbial exudates, and earthworm activity act as “binding” agents for improving soil structure.

Soils for the Gardener

Lumbricus spp. - Nightcrawler

SOILS FOR THE GARDENER A wonderful earthworm website

http://www.sarep.ucdavis.edu/worms/

Soils for the Gardener What would a root need to survive in the

soil habitat? Water

Soils for the Gardener Water

There’s two kinds of people in the world:

Soils for the Gardener

WaterThere’s two kinds of people in the world:

Those that over-water

Those that under-water

Water Conservation

Know your soil reservoir Rooting depth of the plant

How deep to water

Leafy vegetables and annual bedding plants 6 inches to 1 foot

Small shrubs, cool-season turf, corn, tomatoes 1 to 2 feet

Large shrubs, trees, warm-season turf 1.5 to 5 feet

Water Conservation

Know your soil reservoir Rooting depth of the plant Soil water holding capacity

Soil water characteristics for typical soil texture classes

Soil Texture Plant-available water per

foot of soil depth

Gallons of water per

cubic foot of soil

Sand 0.5 – 1.0 0.33 – 0.66

Sandy loam 1.0 – 1.5 0.66 – 1.00

Clay loam 1.5 – 2.0 1.00 – 1.33

Clay 1.5 – 2.5 1.00-1.66

Water Conservation

Know your soil reservoir Soil water holding capacity Rooting depth of the plant Track storage capacity of the reservoir

“Feel Test” pg 79 MG Handbook

Water Conservation

Know your soil reservoir Soil water holding capacity Rooting depth of the plant Track storage capacity of the reservoir

“Feel Test” pg 79 MG Handbook Soil Moisture Meters

Water Conservation

Know your soil reservoir Soil water holding capacity Rooting depth of the plant Track storage capacity of the reservoir

“Feel Test” pg 79 MG Handbook Soil Moisture Meters

Set Priorities

What about fruit trees?

Soils for the Gardener What are the impacts of over-

watering on the habitat of the plant?

Remember the roots need Space Air Water Food

Soils for the Gardener What are the impacts of over-watering on

the habitat of the plant?

Pore spaces are filled with water Roots can’t respire Nutrient uptake reduced Disease incidence may increase Impacts on other soil microflora and fauna

Soils for the Gardener What are the impacts of under-watering

on the habitat of the plant?

Soils for the Gardener What are the impacts of under-watering

on the habitat of the plant?

Water requirements of plant not met Less root growth Less nutrient uptake Impacts on other soil microflora and fauna

It’s time to switch presentations and take time to stand and stretch!!

Soils for the Gardener What would a root need to survive

in the soil habitat?

Food - Is the root a fussy eater?

Plant nutrients

the root does not care whether its nutrients were derived from organic or inorganic sources – advantages?

NUTRIENTS

PLANTS NEED MANY BASIC ELEMENTS FOR PLANT GROWTH –

-NITROGEN (N) -MANGANESE (Mn) -PHOSPHORUS (P) -BORON (B) -POTASSIUM (K) -CHLORINE (Cl) -CALCIUM (Ca) -COPPER (Cu) -SULFUR (S) -MOLYBDENUM (Mo) -MAGNESIUM (Mg) -OXYGEN (O) -IRON (Fe) -CARBON (C ) -ZINC (Zn) -HYDROGEN (H) -NICKEL (Ni)

Soils for the Gardener Plant nutrient deficiencies

Absolute deficiency

Nutrient is absent from soil What type of soils?

Addition of organic matter may not provide all that the root needs will increase the ability of the soil,

especially sandy soils, to hold onto nutrients

Soils for the Gardener

Plant nutrient deficiencies Induced deficiency

Nutrient is present in adequate amounts

Something is preventing its uptake ? ? ?

Induced deficiency

Nutrient is present in adequate amounts

Something is preventing its uptake Low water availability Low oxygen availability Damage to root system from disease Soil pH

Soil pH measures active acidity

(Source: "Nutrient Management for Agronomic Crops in Nebraska," EC01-155)

pH of the soil Relative acidity or alkalinity

Function of hydrogen ion concentration

Acid soils have pH =< ?

Alkaline soils have pH=> ?

pH of the soil Most plants prefer pH = ?

What are some exceptions?

Why is a neutral pH preferred?

Effect of soil pH on nutrient availability

Our next topic for today Basic soil principles The things we add to our soils

Amendments Mulches Compost

Fertilizers and Soil Amendments

Which one is it?

Fertilizers affect plant growth directly improve the supply of available nutrients

Amendments affect plant growth indirectly improve the soil’s physical condition

Amending Landscape Sites

Courtesy of UC OHRIC

Amending Landscape Sites

Courtesy of UC OHRIC

Amending Individual Planting Sites

Courtesy of UC OHRIC

Amending Annual Planting Sites

Courtesy of Aggie Horticulture, TAMU

Photo courtesy of Gary Johnson University of Minnesota Extension Service

Amending plantingsites for trees and why we don’t recommend it

Fertilizers and Soil Amendments When should you amend a landscape soil?

Not all sites require amendments

Important to clearly identify the problem Chemical Physical

Fertilizers and Soil Amendments Chemical Problems in Landscape Soils

Where soil pH is high - sulfur takes time - mediated by

microorganisms temperature and moisture dependent

Where soil pH is low - lime can increase rather quickly

Soluble Salts

Soluble salts come from several sources

Salt moves with water Salts that ARE dissolved in water Salts that are ADDED to water Salts that GET dissolved in water

A – Components of Salinity

Cations:Ca++

Mg++

Na+ (toxic ion)K+

Anions:Cl- (toxic ion)SO4

--

CO3--

HCO3-

NO3- (nitrates)

pH Specific Ion Toxicity:Na, Cl, Boron

Alkalinity:CO3

-- + HCO3-

A - Salts in water

1 acre-ft of water with an EC =1 contains

1 ton of salt or 2 tablespoons of salt per 10 gallons

Salt Accumulation with Drip Irrigation

Drip line

Salt Accumulation

Balancing deep percolation with distribution uniformity with . . .

What is Compost????

UC definition of Compost:

“Compost is the biologically active material that results from microbial decomposition of organic matter under controlled conditions.”

(Compost Production and Utilization, UC ANR Pub. #21514)

COMPOST HAPPENS!

Felder Rushing’s Two Rules of Composting:

1)Stop throwing that stuff away!

2)Pile it up somewhere!

A Compost Pile is an Ecosystem

Function =

decomposition of

organic matter

The Compost Processdepends on:

Organic Matter Composition Carbon (Browns) Nitrogen (Greens)

Microorganisms Macroorganisms Water Oxygen Temperature

Organic Matter: Carbon or “Browns”

Carbon rich sources are called “browns” Usually dry, low moisture content, lightweight Examples: dry leaves, straw, sawdust, wood chips, corn stalks

Organic Matter: Nitrogen or “Greens”

N is needed to get the decomposition process started and keep pile “cookin”

Examples: vegetable and fruit scraps, grass clippings, coffee grounds, manures, and alfalfa hay

Carbon:Nitrogen Ratio

Optimal C:N ratio is 30:1 at an elemental level

Carbon supplies energy for bacteria and Nitrogen supplies nutrients (proteins).

Balance material ratios to get 30:1 ratio: e.g.1/5 oak leaves 26:1 1/5 poultry manure 10:11/5 pine needles 85:1 1/5 grass clippings 20:11/5 food scraps 15:1 C:N ratio = ~31:1

Approximately equal volumes of greens and browns provides a

good C:N ratio

Microorganisms

Bacteria begin breakdown process – aerobic bacteria feed on plant sugars and respire to “heat up” pile

In the right conditions, population growth is amazing—bacteria can double every hour!

Microorganisms

Four Types of Bacteria

Psychrophilic: work at lower temperatures

Mesophilic: thrive between 70-90°F

Thermophilic: work from 113-200°F short “work week” 3-5 days, turn pile to reactivate

Anaerobic Closed air bins, wet piles or too dense - not aerated Fermentation & odors from anaerobic decomposition Pile does not heat up, so doesn’t kill pathogens/weeds

More Microorganisms…

Fungi: active in end stages of composting - live on dead or dying material

Actinomycetes: halfway between

bacteria & fungi – gray-white

cobweb type material in compost pile, also active in later stages of composting

actinomycetes

Macroorganisms

As temperatures decline, population diversity increases:

Nematodes: sightless, brainless roundworms, <1 mm long.

prey on bacteria, protozoa, fungal spores

Fermentation or mold mites Springtails

tiny white insects

Macroorganisms

Wolf spiders: build no webs, run free hunting their prey

Centipedes: flattened body, long legs, fast moving

Millipedes: worm-like body with hard plates, up to 6” long. Slow

moving vegetarians that help in breaking down OM.

Sowbugs & pillbugs (Isopods) small, fat-bodied decomposers with gills. Pillbugs

roll into a ball, sow bugs don’t. Feed on rotting woody materials

Pillbug

Sowbug

Macroorganisms

Beetles: rove beetle, ground beetle, and feather winged beetle

Earthworms: native redworms

Enchytraeids, (Ehn kee tray' id) white or pot worms, ¼ - 1” long, white & segmented

Flies: feed on any organic matter.

Bury kitchen scraps well, keep fatty foods out of the pile to control.

Whiteworms

Macroorganisms

Snails and Slugs: Feed on living plant material, garbage and plant debris.

Fruit beetle larvae: large grubs, 2” long & C-shaped; translucent white, head is dark

brown.

Ants: feed on aphid honeydew, fungi, seed, sweets, scraps, other insects, and

other ants. Compost provides food and shelter. Ants usually mean pile is too dry.

Earwigs: predators of all stages of insects, mites & nematodes, also algae, fungi

& plants.

Water & Oxygen

Balance oxygen and water in the compost pile: 50% moisture + 50% O2

Consider moisture content of added materials (food scraps!)

Compost should be about as moist as a well wrung-out sponge. It should be moist to touch but yield no liquid when squeezed.

Water in the Pile

Wet pile: pull it apart, loosen it, incorporate dry materials and

remake it.

Dry pile: turn & rewet material as it is being turned (some browns

are hard to moisten)

Seasonal considerations!!!

Oxygen Aerobic composting is preferable

Anaerobic decomposition or fermentation may produce compounds toxic to plants produces ammonia & methane gas – smelly!

Passive aeration: air is warmed by the compost process, rises through the pile, pulls in fresh air from the sides.

Active aeration: turn and mix the compost, or build the pile effectively so surface air diffuses in

Temperature!

Temperature is a function of:pile size, oxygen & moisture content

Temperature affects biological activity:

Most microorganisms active between 95 - 160ºF

Best decomposer bacteria thrive at 122 - 131ºF.

Above 140ºF kills pathogens & weed seeds, but

slows decomposition.

Temperature

Optimum is 2 weeks of temperatures around 135º

Turning the compost whenever temperatures get above or below the optimum range produces high quality compost in the shortest possible time.

If compost is properly moist and turning does not cause temperatures to rise, the compost is finished or needs more nitrogen.

“It depends” on: Density of material

Particle size (amount of exposed surface area)

C & N content Moisture content

Aeration Volume

Insulating materials around the pile

How long does it take?

Making the Pile

What kind of bin should I use?

Making the Pile: Important Considerations

Size of pile should be 3’x3’x3’ to 5’x5’x5’ Do you have all the organic material (batch)

or will you add continuously (continuous)? Have you chopped up your materials? Moisture and aeration: what’s the rule? Compost tools: hay fork, aerator…

Composting Methods

Standard Method: Need a variety of

materials Turn it each week 4-6 weeks for

finished compost (summer)

Rapid Composting Method

Need large supply of organic materials

Requires substantial chopping and shredding and more turning of the pile

Can take less than one month in ideal conditions.

Slow, Continuous or Static Method – It’s not a moral issue

If a steady supply of organic materials is not available

Takes very little time or labor

Requires 6 months to 2 years to produce compost

Smaller compost area needed, because pile is built as materials are available

Little if any heat is produced, so weeds & pathogens are not killed

Grass clippings Yard waste Leaves, pine needles Vegetable trimmings Food scraps Wood chips (shredded to size) Newsprint Sawdust

What goes in the Pile?

Disease infected plants Plants with severe insect attack Ivy, morning glory and succulents Pernicious weeds, e.g. Bermuda

grass, oxalis, cheeseweed Cat and dog manures Meat and fish scraps Wood ash (add after composting

is finished)

What does NOT go in the Pile?

BUT…What are some issues that complicate composting???

Compost Happens!

Composting issues

Rodents Raccoons CC&Rs Smell Other???

Correcting Physical Problems in landscape soils

Physical Problems in landscape soils

Adding sand -- just remember the components of concrete!!

What can we add to correct physical problems?

Physical Problems in landscape soils

Correcting Physical Problems Organic materials

Benefits of organic matter as an amendment

Reduces compaction ‘Humus’ -- derived from OM and

resistant to further decomposition aids in formation of soil aggregates

Organic Matter provides food source for earthworms and saprophytic organisms

When can the addition of OM cause problems in the home

garden? Cyclic relationship between

activities of decomposers and availability of nutrients

Especially NO3- Induced deficiencies

Nitrogen Immobilization

NO3- depletion time

Time

Activity of decay organisms

High C:N Addition

Nitrogen level of soil

What about OM as a mulch?

Mulches are not incorporated into the soil

Petunia example!!

Petunia Example

Petunias planted and

then mulched

Petunias planted – no

mulch applied

Mulch applied and then

petunias planted

Petunia Example

Petunias planted and

then mulched

Petunias planted – no

mulch applied

Mulch applied and then

petunias planted

Mulches can save water

Materials put on top of soil Reduce water evaporation – why? Prevent weed problems Buffer soil temperatures

Be careful with native plants!! Desert pavement serves as a mulch

Depth of mulch depends on materials – why?

Depth of mulch depends on materials

Coarse - 4 to 6 inches

Medium - 2 to 4 inches

Depth of mulch depends on materials

Fine mulches need only about 1” depth

Desert Pavement as a mulch

Yamanaka et al 2004

Should I use fertilizers?

Garden soils rarely contain all required nutrients

Equally rare for garden soil to be deficient in several

Add only the ones that are deficient

Careful with nitrogen in cold climates

Don’t apply fertilizer before projected rain event

ww

w.p

hsc

ho

ol.c

om

Nitrogen deficiency curcurbit

Phosphorus deficiency tomato

Potassium deficiency sunflower

Fertilizers and Soil Amendments How much should I fertilize?

“Two kinds of people in the world”

Problem: Contamination of surrounding water bodies

Nitrates, Phosphorous

Nitrates

Eutrophication

Lake

Groundwater

Apply Fertilizers Efficiently

Time Fertilizer Application to Plant Uptake - Grapes

N partitionin

gN

Time

Fertilizers and Soil Amendments

How much should I fertilize?

“What is the most limiting factor for plant growth - is it really nutrients?”

Soils for the Gardener

How might thisaffect plant growth?

Courtesy of Ohio State University

Fertilizers and Soil Amendments Types of Fertilizers

Inorganic Fertilizers: CSFML says not derived from plant or animal residuesAdvantagesfast-actinglow in cost

Disadvantagesleachingsalt effects

Fertilizers and Soil Amendments Types of Fertilizers

“Complete” fertilizers: contain at least Nitrogen (N) Phosphorus (P) Potassium (K)

Fertilizers and Soil Amendments By law, guaranteed content of fertilizer

must be stated on bag

Expressed as % of each plant nutrient applied

N - P - K

Fertilizers and Soil Amendments N - P - K 12 - 12 - 12 First number: % nitrogen (N) Second number: % phosphoric acid P2O5

Third number: % potash K2O

Nitrogen (N)

No conversions required

Fertilizers and Soil Amendments

PHOSPHORUS (P)

Expressed as phosphoric acid P2O5

Phosphoric acid contains only 43% P

To convert from P2O5 to P

P= P2O5 x 0.43

Fertilizers and Soil Amendments POTASSIUM (K)

Expressed as potash, or K2O

Potash contains only 83% K

To convert from K2O to K

K= K2O x 0.83

Efficient fertilizer applications

Courtesy of Aggie Horticulture, TAMU