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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