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Organic Gardening
Erika Yigzaw B.Com, LL.B (Hons), Master Gardener
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DIY?
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No! GIY!
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What does the term “Organic Gardening” Mean to you?
Natural (what does that mean?)
Pesticide free (not necessarily?)
Respects natural patterns?
Remember that organic chemistry does not = organic
agriculture!
Question?
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Between the National Organic Program (NOP) run by the US
Department of Agriculture and the term as used in home
gardening….
Organic Agriculture Federally Defined USDA National Organic
Standards Board 1995: “Organic agriculture is an ecological
production management system that promotes and
enhances biodiversity, biological cycles and soil biological
activity. It is based on minimal use of off-farm inputs and on
management practices that restore, maintain and enhance
ecological harmony.”
Distinguish
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Farming that mimics natural ecosystems and maintains and
replenishes the fertility of the soil.
No use of synthetic chemical pesticides and fertilizers
Organic Foods –Grown and handled according to NOP standards
–Minimally processed to maintain the integrity of the food without artificial preservatives or irradiation
Based on ecological principles –Ecology: Nature’s household • Study of the environment and the relations of organisms to each
other and their surrounding "An organic farm, properly speaking, is
not one that uses certain methods and substances and avoids others; it is a farm whose structure is formed in imitation of the
structure of a natural system that has the integrity, the independence and the benign dependence of an organism"
—Wendell Berry, "The Gift of Good Land"
Organic Agriculture
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Use of synthetic chemicals tied to history of chemicals and
genetics in agriculture – put us on a chemical treadmill with
high inputs (energy, water, fertilizer) and expectations (green
lawn in middle of summer, no insects)
Home gardening: Relates to source of products used and
how they are derived
NOP program defines organic extensively, but there is still
confusion
My emphasis is on Low Input Organic Gardening – not just
replacing synthetics with organic alternatives (although that
is a good start!) but by building the ecosystem in your
garden to a self sustaining level…
Organic Home Gardening
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Synthetic
Faster but non specific (kills everything, victims may develop resistance, unintended
victims)
Easily available (but now, so are organic alternatives)
Use by Home Gardeners:
http://www.ext.vt.edu/pubs/plantdiseasefs
/450-725/450-725.html: 100 million pounds –71 million pounds herbicide –17 million pounds insecticide/miticide –12 million pounds
fungicides. Does Not include use by landscape companies)
Health risks, risks to wildlife (leaches into waterways), cost, energy … huge implications for sustainability…
Why Go Organic?
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Self education required for organic – requires a different
mindset and aesthetic – e.g. a green lawn has been a sign of
prosperity for centuries, its tough to let it go brown mid
summer!
In 2005 5% of households used organic methods only, 31%
used hybrids – these numbers are expected to double
(National Gardening Association. (2005). Environmental Lawn and
Garden Survey. South Burlington: National Gardening Association.
Retrieved May 12, 2008 at http://www.gardenresearch.com/index.php?q=show&id=2896.)
Organic agriculture movement started in 1940s with Rodale. Rachel Carson’s Silent Spring in 1962 highlighted pesticide damage,
Organic Food Organic Foods Production Act, Farm Bill 1990 -uniform
national standards National Organic Standards 2002 -standards adopted for “organic" labeling
US Gardening is Going Organic…
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Ecology •Study of the environment and the relations of
organisms to each other and their surrounding
Ecosystems •Collection of interacting organisms and non
-biotic components in the physical environment
Look at the ecosystem in your garden…
Key Concepts:
•Soil Building
•Conservation
•Biological Pest Management
Ecological Approach
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What is Tilth?
Tilth • the state of aggregation of a soil especially in relation to its
suitability for crop growth –http://www.m-w.com/dictionary
Our job as gardeners is to maintain and enhance tilth in soil through
addition of composted organic material (balanced) and regimented care
Very important to avoid COMPACTION, which prevents air getting to plant roots.
Soil Building and Tilth
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See http://soils.usda.gov/SQI/concepts/soil_biology/soil_food_web.html
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What is Soil?
Source: http://www.hort.purdue.edu/
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Provide food for soil biology
Feed the soil with organic matter, which:
•Provides long term fertility
•Improves quality of most soils
•Breaks down to form humus (natural glue)
•Strengthens aggregates
•Improves water holding capacity
•Releases plant nutrients
•Provides food for beneficial organisms
•“Feed plants by feeding the soil”
How Do We Build Soil?
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Low C/N ratio, high nutrient value:
raw manure, blood meal, feather meal, less
contribution to organic matter, use sparingly,
do not exceed N and P requirements
Medium C/N ratio, lower nutrient value:
compost, leaf mulch and cover crops, add in
large quantities
High C/N ratio, can immobilize N:
straw, bark & sawdust
What is “Organic Matter”?
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Plants need food to grow. The Sun provides energy through
photosynthesis. But plants also need:
• Macronutrients (Large amounts):
Nitrogen, phosphorous, potassium, calcium, magnesium, sulfur •
• Micronutrients (small amounts)
Boron, manganese, zinc
Law of the Minimum
Whatever nutrient is in short supply will limit
growth
Soil test… nitrogen an issue in OR because of rain levels….
Fertilizer?
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Nitrogen cycle important to understand. Atmosphere contains 78%
N but it is unavailable to plants. Some plants e.g. rhizomes (peas etc) fix atmospheric nitrogen.
Always must provide nitrogen sources:
•Previous compost and manure applications
•Crop residues
•Cover crops (legumes fix nitrogen, grasses reduce losses)
•Soil organic matter (0.23# -0.69# / 1000 sq. ft. for each 1% organic
matter)
•Supplemental fertilizers (i.e.. blood, feather, corn, fish meal)
Organic nitrogen sources do accumulate, but still add new each
year
Nitrogen: How to Get It
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The following use up or leach nitrogen from the soil. Avoid
unnecessary reductions in your garden’s nitrogen
Rain and over-irrigation = leaching. Always water just
enough. Use drip irrigation rather than overhead watering.
Cultivation: avoid tilling, no till or raised beds retain more
nitrogen
Evaporation –incorporate amendments, mulch to reduce
Crop removal –incorporate residues through compost,
digging in residues
Goal = Minimize leaks in the nitrogen bucket
Nitrogen: How to Keep It
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Soil organisms break down the remains of plants and other
organisms.
This process releases energy, nutrients, and carbon dioxide,
and creates soil organic matter.
Organic gardening keeps soil organisms at optimal levels.
Monocultures, synthetic fertilizers and pesticides destroy soil
organisms.
Soil Organisms
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Cover Crops
Compost
Deep cultivation
Fertilizing
Weed control
Mulch
Organic Fungicides
Organic Herbicides
Organic Gardening Methods
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•Reduce erosion
•Protect soil structure
•Fix Nitrogen and improve nutrient
availability
•Supply N without increasing soil P
•Reduce nitrate leaching
•Increase soil organic matter
•Improve mycorrhizal winter
survival
•Reduce weed pressure
•Provide nectar & pollen for
beneficial insects
Cover Crops
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Compost meets many needs in
the garden:
- Improves soil structure by
adding organic matter
- Conserves nitrogen
- Feeds soil microorganisms
- Provides macro and some
micronutrients
- Saves money
Compost
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Can be easy or complicated. Few gardeners could make enough to meet all needs. Add 2 inches per crop season.
Easy:
Make a pile of organic materials – pruned branches, weeds (without seeds), leaves, manures. Leave it for approx 1 year. Use the compost that is
underneath.
A bit more work:
Put the same organic materials into some kind of bin and turn every month or so
Easier but more expensive:
Put materials into a compost tumbler
Make Your Own Compost
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See videos at www.youtube.com/achstv
Make Your Own Compost
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Double digging –Broad fork
–Raised beds
For landscapes-mix composted
organic material 18”deep
–Mechanical digger
Deep Cultivation
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USDA List of Approved Fertilizers
Always check cost ratio – some are very expensive for NPK
levels
Organic Fertilizers (OSU Master Gardener Materials) Material % N % P % K
Fertilizing
•Cotton seed meal 6-7 2 1
•Blood meal 12-15 1 1
•Alfalfa 2 0.5 2
•Bat guano 10 3 1
•Fish meal 10 4 0
•Fish emulsion 10 4 0
•Bone meal 1-4 12-24 0
•Rock phosphate 0 25-30 0
•Greensand 0 0 3-7
•Kelp meal 1 .1 2-5
•Organic fertilizer calculator at http://smallfarms.oregonstate.edu
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Old fashioned weeding is the cheapest and most effective
method: Weed after watering or rain, don’t let weeds set
seed (up to 100k seeds that can last 100 years!), hoe in hot
weather and weeds will die, hoe when weeds are small.
Other methods:
Weed Control
•Plant transplants so they have
a head start on weeds
• Use Cover crops
• Crop rotation
• Avoid bringing new weeds to
the garden in manure, straw
•Stale seedbed
•Collect edible weeds
•Use weeds in compost (not
once seeded)
•Plant closely together
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Landscape fabric
• Plastic mulch –Black plastic
–Purchase, disposal &
irrigation
• Straw mulch –Weed seeds
–Irrigation & nitrogen
• Sheet Mulch –Newspaper
/cardboard
Mulch
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Cut existing material to ground –Add nutrients –Water –Thick
newspaper –Thick mulch
Don’t try with perennial weeds
Sheet Mulch
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Vinegar (acetic acid)
Clove/citric acid based
Herbicidal Soap: Contact herbicide and is non-selective. OK
for annuals but not very effective for perennials
Corn gluten: Pre-emergent (i.e. supposed to stop weed seeds
germinating) Not effective – Good N fertilizer
Organic Herbicides
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1. Plough or spade
2. Prepare seedbed
3. Irrigation or rain then wait 1-2 weeks
4. Flame, vinegar or herbicides, or very light cultivation
5. Repeat if possible
6. Plant or sow seed
Stale Seedbed Method
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Are organic alternatives to synthetic insecticides
Can still be toxic, so still take precautions when using
Other alternatives are to diversify plantings, use right plant for
right place, choose adapted varieties, choose resistant
varieties, build the soil (cover crops, compost, don’t cultivate
when too wet or dry), water correctly (adequate, in morning,
drip not overhead to avoid spreading fungal diseases), feed
adequately (compost or organic fertilizer), plants and
habitats for beneficial insects, plant to allow some airflow,
tolerate some damage, hand pick insects, rotate crops, use
chickens!
Healthy plants resists pests and recover quickly & healthy
landscapes prevent pest outbreaks
Managing Pests
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Principles of IPM
• Prevention
• Monitor the plants
• Identify the pest organism –learn
life cycle (e.g. codling moth
larvae emerge in March/April)
• Establish an acceptable injury
level
• Manage the situation –Cultural
–Biological –Chemical (organic
and synthesized)
• Evaluation
Integrated Pest Management
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Horticultural oils • Copper based • Sulfur • Serenade (Bacillus
subtilus) • Baking soda (K) This is a peach tree grafted with
two curl resistant cultivars. Cultivar 'Q 1-8' on the left and the
cultivar 'Mary Jane' (with lots of curl) on the right.
See Materials Allowed for Organic Disease Management at
http://ipmnet.org/plant-disease/articles.cfm?article_id=44
Organic Fungicides
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• Azadirachtin-Neem • Bt-biological • Beauveria-biological
• Horticultural oils • Insecticidal soap • Iron phosphate-slugs
• Kaolin clay • Lime Sulfur • Pyrethrins • Rotenone •
Spinosad-biological • Sulfur
With All Products • Label is the law • Identify plant and pest
and confirm on label for allowed uses of products • Read
and follow the directions! • Wear proper eye protection,
mask, clothing, gloves, etc.
Organic Pesticides
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Diverse plantings encourage beneficial
insects
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Choose the right plants – ones you like and ones that like
your climate
Take care of your soil – don’t plant directly into unworked
ground, add lots of compost, befriend someone with a
horse…
Allow for a diverse range of plantings – mix flowers and herbs
in with your vegetables
Don’t plant things when its too cold out
Don’t work the soil when its too cold and wet
Have a sense of humor –
Keys to Successful Organic Gardening
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Hardiness
Different species and varieties have varying hardiness and
each requires different treatment. Find out your zone and
choose plants that grow in that zone.
Choose the right plants
This January 2008 snow falls
on our one year old plants
tested their hardiness. We will see how many plants
were affected once the
plants put on their new
growth.
Photograph by Erika Yigzaw
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Attract beneficial insects
Lavender is one of many plants that attracts many beneficial
insects, including bees, hoverflies, and butterflies.
In fact, bee keepers love putting their hives at lavender farms, as the
lavender honey is delicious!
Bees on lavandin at the ACHS
garden in John’s Landing.
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It is great fun to grow your own food organically
Get kids and spouses involved – even the most hardened heart
warms when picking the first spring peas!
Gardens can be easy to
look after Grow what you like to eat. Don’t
waste time growing things that your
family wont eat anyway.
Weed regularly, right after watering,
and before weeds go to seed.
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Helpful Links
Photographs
by Erika
Yigzaw at Hood River
Lavender
Farm.
Australasian College of Health Sciences www.achs.edu
Apothecary Shoppe www.apothecary-shoppe.com
Erika’s blog: http://confessionsofamastergardener.blogspot.com/
Oregon Master Gardener Program http://extension.oregonstate.edu/mg/
Find the last frost date in your area and estimated times to plant based on your zip code from the Farmer’s Almanac
http://www.almanac.com/garden/plantingtable
/index.php
Master Gardener Hotline for any questions: 503 725 2300
Metro Events (including Gardens of Natural Delights):
http://www.oregonmetro.gov/index.cfm/go/by.web/id=576
Tour De Coops:
http://growing-gardens.org/portland-gardening-resources/chickens.php
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Essential Oil Production:
This microscope photograph enables you to see the essential oil sac
on the leaf of a lavender plant.