Nurture your Soil Organically

If you are new to the term ORGANIC GARDENING, this page is for you. If you are an ORGANIC GARDENER, we hope you will enjoy picking up a new tip or two.

Raising vegetables using commercial chemical fertilizers was introduced to the food growing community shortly after World War II. It was believed that through the miracle of chemistry, there could be a easy, push button, predictable, get it now with no chance of failure to successful growing of food. For the most part this approach seemed to work. Only after a few decades did we really realize what we were doing to the soil, the atmosphere and the quality of the food being raised this way.


It’s the only way to reverse the down hill trend we are gong in.

Listed here are the intro approaches to ORGANIC GARDENING. Let’s start with the most logical beginning, “THE SOIL”

Improve Soil Structure

Unfortunately, you can’t build loam by simply mixing the component parts. However, if you have a non-loam soil you can improve its drainage while at the same time improving air circulation by adding organic matter such as compost, ground bark, sawdust, leaf mold, manure, and peat moss; the goal, a crumbly, granular soil.

Two mineral compounds, gypsum and lime, can improve aeration and drainage of clay soils. Each contains calcium which causes clay particles to group together, forming soil “crumbs” larger than the individual particles. That makes the air spaces between crumbs bigger, too. Do not use gypsum and lime as substitutes for organic materials, because they do not directly aid soil microorganisms, nor do they contribute to nutrient retention.

CLAY drains slowly. SAND drains too rapidly. LOAM drains least.

Use gypsum if your clay soil is highly alkaline because of excess sodium. Spread file gypsum on top of the soil (the usual recommendation is “like a light snow”) and spade it in. This will be approximately 35-50 pounds per 1,000 square feet.

If high acidity of clay soil is a problem, add lime. First, be sure to test your soil lo determine its pH A soil test with us will recommend the quantity of lime to add to your soil for the plants you plan to grow.

A large amount of clay particles in a soil means limited air space. The tiny clay particles lump together, holding tightly to water, and little space is left for air to enter. Spading decaying organic matter into this heavy soil “lightens” it in two ways: The coarse organic particles act as temporary wedges between compacted soil particles; the very fine, more fully decomposed parts of the organic matter (humus) are sticky and act as a glue to aggregate or hold the fine clay particles together in small crumbs. This loosens up the clay and allows it to “breathe”.

Sandy soils have the opposite problem from clay soils–there is too much space around the large irregular particles. This lets in plenty of air but fails to hold water. Add a fine textured organic material to sandy soil and particles will lodge in the large spaces between the sand grains, acting as sponges to catch the water and keep it within the reach of roots.

Soil Nutrients and How to Obtain Them

After soil structure the next important concern is soil nutrients and how to obtain them; read on.

Nitrogen-Phosphorus-Potassium Values in Organic Fertilizers

Written By Rose Penhallegon OSU lane County Extension Horticulture Agent; Edited by Karen Ailor<
OSU Extension Service – Lane County Office, 783 Grant St., Eugene, OR 97402

Organic fertilizers are used to improve soil quality and tilth, and to provide nutrients for plant growth. They provide nitrogen, phosphorus, and potassium, as well as other elements essential for plant development and overall good health.

Nutrient values vary greatly among organic fertilizers. They also vary greatly for a given organic fertilizer. For example, as the table on the following three pages shows, the nitrogen in raw bone meal ranges from 2 to 6%, and the phosphorus from 15 to 27%. Differences reflect variations in the age of organic material, its decomposition rate, application method and timing, incorporation time, time exposed to the elements (rain, sun), the percentages of organic matter and water the material contains, carbon-to-nitrogen ratio, microbe population, and soil type. Values for manurers vary according to time of year, time in the open air, percentage of added straw, and rate of incorporation. The speed of release shown in the table indicates how quickly nutrients are made available to plants.

Some materials are regulated by Oregon Tilth. To be considered organic, they must result from organic farming methods. For example, cocoa shell meal and cottonseed meal must not be contaminated with pesticide residues. Raw manure is also regulated; composted manure is not. Wood ashes must not be from treated wood.

Nitrogen, phosphorus, and potassium are represented by N, P, and K in the table headings, to conform to standard commercial practice in labeling fertilizers. Phosphorus is actually present in the form of P205, potassium as K20.

Top sources of nitrogen (N):

  • Bat guano
  • Blood/blood meal
  • Crab waste
  • Feather meal
  • Fish meal (dry)
  • Hair
  • Hoof/horn meal
  • Shrimp waste

Top sources of phosphorus (P):

  • Bat guano
  • Bone meal
  • Crab waste
  • Cucumber skins (burned)
  • Hair
  • Mushroom compost
  • Phosphate
  • Shrimp waste

Top sources of potassium (K):

  • Crab waste
  • Cucumber skins (burned)
  • Granite (dust)
  • Greensand
  • Kaolinite (clay)
  • Kelp
  • Sulfate of potash magnesia
  • Wood ashes

For a complete detailed breakdown on how these organic products behave in organic gardening, please see OSU Extension Service »

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