Download - Beyond "Dirt" - Garden Soil and Amendments

Garden Soil &Amendments

Independence GardensPortland, OR

January 2012© Independence Gardens LLC

Download the handout that goes

along with this slideshow!

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Tuesday, January 31, 2012

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Topics We’ll Cover• What is soil?• Soil issues worldwide• Soil issues in your garden• Soil components• pH• Nutrients• Soil testing• Amendments

What We’ll Cover TodayPreview

Got Questions? Please ask as we go along.


What is soil?

• Soil is an edge– Microorganisms + minerals

• Soil is the basis of a diverse ecosystem

– Broader base more room for everything else

• Soil is a process– Anything but static!

• Soil is a relationship– Between components,

conditions, inhabitants, and YOU

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http://www.hylandseeds.com/images/soil%20photo.jpg




Soil worldwide

http://www.utafoundation.org/soil_loss.jpg




Soil in your garden

• Top 6-8 in.– Where plants do most of their feeding

• You can look for– Structure– Texture– pH– Nutrient presence/availability– Organic ma!er– Biological activity

• A single acre of good soil can support 2000 lbs. of animal life above the soil surface and 4000-6000 lbs. below (“microherds”)

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Soil components

• Mineral components and organic ma!er = “solid”

• Air and water = “space”– Soil microorganisms live

in this part of the soil, and they are what make nutrients available to plants

http://courses.soil.ncsu.edu/resources/physics/composition/compo3b.png






http://school.discoveryeducation.com/schooladventures/soil/images/particle_sizes1.gif

Soil particles• Clay

– Less than 0.002 mm• Silt

– 0.002 mm – 0.05 mm• Sand

– 0.05 mm – 2.00 mm• Fine pebbles

– 2.00 mm – 5.00 mm• Medium pebbles

– 5.00 mm – 20.00 mm

• Coarse pebbles– 20.00 mm – 75.00 mm






http://www.omafra.gov.on.ca/english/engineer/facts/vfss_manual/vfssman37f1.png

Soil layers

• O (organic)• A (assimilation)• E (elluviation)• B (banking)• C (chemical/

constitution)• R/D (durable)






Soil types

• Not just “dirt”– Dirt is soil where it’s

not supposed to be• Loam is ideal for

garden soil– 40% silt– 40% sand– 20% clay

http://www.dirtguytopsoil.com/images/soiltriangle.gif




Soil food web

• "is is who/what shares your soil with your plants

http://www.magicsoil.com/MSREV2/Soil_Food_Web_Soil_Biology_Primer.jpg




pH

• Logarithmic scale, 0 (acid)-14 (base)

http://packerpedia.wiki.packer.edu/file/view/pH_Scale.jpg/31722773/pH_Scale.jpg




Nutrient availability

• Soil nutrient supermarket• Our soils are generally ~5.5• Ideal garden soil is 6.8-7.0

• Other factors affecting availability include:

– Soil texture– Soil temperature

– Amount of organic ma!er– Microbial activity– Interactions with other nutrients

• Competition for sites on soil particles

• Forming insoluble compounds

http://attra.ncat.org/images/organic_soil/chart.jpg




Nutrients


Essential plant nutrients

• From air and water– Carbon (C) Hydrogen (H) Oxygen (O)

• Macronutrients– Nitrogen (N) Phosphorus (P) Potassium (K)

• Secondary macronutrients– Sulfur (S) Calcium (Ca) Magnesium (Mg)

• Micronutrients– Boron (B) Chlorine (Cl) Copper (Cu)– Iron (Fe) Manganese (Mn) Molybdenum (Mo)– Zinc (Zn)


How to learn more

• Shake test– “Layer Away”

• Perc test• Watering test• pH test• Soil test• “Weed”

observation• Bug’s eye view


Soil testing: Do it...if:

• Nutrient testing– You plan to grow most or all of your own food

yourself– You’re growing in a small, homogenous,

contained space– and/or you’ve been experiencing problems

• Toxics testing (esp. Pb)– You are aware of previous uses of your land that

were “dirty” or sources of pollution in the ‘hood

– You don’t know how your land has been used in the past

– You’re growing within 6 $. of a house built before 1978

– Small children/elders/animals will eat the harvest

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What to do with your new info

• Awareness...a!ention...and amendments!– Organic ma!er

• Adding it is the most important thing you can do for your soil!• 1-2 times a year, add 1-2 in. of compost, mixed into the top 8 in. of soil

– Soil conditioners improve structure and/or provide nutrients• Examples: coffee grounds, bloodmeal, kelp, peat moss, coco coir, lime,

etc. (some are organic ma!er, some are not)• Apply as needed

– Mulches have many bene%ts but are not soil conditioners– Fertilizers aren’t designed to help your soil


Adding organic ma!er

• Increases in%ltration of water from soil surface• Increases water-holding capacity in sandy soils and

drainage in clay soils• Improves nutrient retention (reduces leaching)• Improves nutrient availability• Examples: garden/household compost,

(composted) manure, mushroom compost, cover crops/green manure, worm castings


Changing pH

• Test %rst– DIY kits– Professional/lab test

• To raise pH– Add lime (maximum: 5 lbs./100 sq. $.)– Add wood ash (maximum: 1.5 lbs./100 sq. $./yr.)

• To lower pH– Add organic ma!er– Add sulfur (maximum: 5 lbs./100 sq. $.)


Ongoing nutrition

• Know what’s there already• Conserve what is present

– Maintain pH– Reduce erosion and leaching– Recycle nutrients! (compost/mulch)

• Add nutrients– Commercial/packaged fertilizers

• Avoid fertilizing dry soil• Always follow instructions on the label

– Organic ma!er• Include cover crops/green manures to protect and enhance soil


Organic fertilizer N-P-K values

Thanks to Naomi Montacre for this chart.


A few more pointers

• De%ne your garden space– One way to do this: use raised beds– Or…you can use containers

• "is is a whole different kind of soil and soil-building

• Avoid compaction– Including mechanical tilling

• Avoid unnatural layering– For example, in%lling a raised bed and not incorporating the

new soil into the native soil• A note on toxins

– Know where the risk is and the common pathways for exposure


And "nally...

• To get neglected soil into shape for THIS season– Incorporate 1-6” of compost– Add kelp meal (K), bone meal or

a mineral mix (P), and an organic N source (alfalfa meal, blood meal, or %sh meal/emulsion) according to package instructions

• To protect your soil for next year– Mulch regularly– Sheet mulch or cover crop

through the winter


Questions?
