Organic gardening promotes a healthy environment and supports healthy plants and foods. However, it is not simply a matter of replacing synthetic chemicals with “natural” products. For example, conventional fertilizers supply soluble nutrients that are readily available to plants whereas organic fertilizers depend on soil microorganisms to break them down into elements that plants can use. This means it takes some time for an organic fertilizer to provide any benefit. In addition, it takes larger quantities of organic fertilizer – which also must be applied with greater frequency – to be as effective as the synthetic fertilizer. On the other hand, synthetic pesticides can more readily be replaced with safe, effective natural products.  There are no organic herbicides to eliminate weeds, but there are effective mechanical and cultural methods of control. There is no doubt, however, that by minimizing the environmental impact organic methods offer the possibility of a sustainable future. Useful Websites

Here are some ways to create an “organic” environment in the garden:

• Stop using synthetic fertilizers, pesticides, and herbicides.
• Use row covers, grease bands, sticky cards, and other organic pest control barriers and traps.
• Use organically grown seeds, bulbs, and plants and plant sustainable plants.
• Make compost from garden and home waste or buy composted manure and plant waste to enrich the soil.
• Start seeds and plant plugs in biodegradable pots and trays; reuse plastic pots.
• Learn to recognize “good” bugs and avoid killing them.
• Collect rainwater and reduce water use as much as possible. Remember, one inch of water per week is all your lawn and plants need.
• Use traditional methods if circumstances point to them as the best choice.
• Use mechanical and cultural methods to control weeds.
• Manage all garden elements organically – vegetables, ornamentals, and lawns.

Soils
If you have clay soil, silt soil, peat soil, or sandy soil you need to amend it so that the soil has roughly equal parts of each particle type. Then the soil is called loam and it has an ideal structure. Manure and composted plant materials add organic matter, which aids in moisture retention, helps reduce compaction, and can buffer extremes in pH. It also helps maintain the structure and nutrient holding capacity of the soil.

Avoid compacting the soil because it will be airless and thus a poor environment for organisms that inhabit the soil. The soil can be protected by reducing traffic and not walking on or cultivating wet soil.

The soil structure can also be damaged by excessive digging and cultivating, so keep these activities to a minimum. Digging also encourages weed growth by bringing dormant weed seeds to the surface where they germinate. On the other hand, digging is an effective way to reduce compaction.

Cover the soil with mulch to protect the structure, insulate the soil from rapid temperature changes, and keep the soil moist. Mulches also suppress weeds and when they  decompose organic material is added to the soil.

Fertilizer and Soil Chemistry
Soil pH, a measure of the soil's acidity or alklinity, can directly influence the vigor and quality of plants, vegetables, and lawns. When the pH is below 7.0, the soil is said to be acidic; when above 7.0, it is alkaline. Lime is apaplied to the soil to increase soil pH. The amount of lime for a particular soil is designated as the lime requirement on soil test reports obtained from soil testing laboratories.

Organic fertilizers are derived directly from plant or animal sources. Inorganic fertilizers are often called commercial or synthetic fertilizers because they go through some manufacturing process, although many of them come from naturally occurring mineral deposits. Neither type is better in every situation, because there are advantages and disadvantages to using either one, according to Ross Penhallegon, horticulturist with the Oregon State University Extension Service. (http://extension.oregonstate.edu/news/story.php?S_No=558&storyType=garde)

Organic fertilizers have a disadvantage in that the nutrient level of organic materials is lower, rate of release is slower, and levels of minerals may vary and are not balanced. Fruits and vegetables often have high nitrogen demands, and it can be difficult to provide sufficient nitrogen from an organic source throughout the growing season of the crop. In addition, availability of nitrogen late in the season can make perennial plants such as raspberries and apples susceptible to winter injury. It is a challenge to provide plants with a readily available organic nitrogen source early in the growing season, yet have it less available in late summer.

Common organic sources for the essential plant nutrients [nitrogen (N), phosphorus (P), and potassium (K)] are: For nitrogen: dried blood, cotton seed meal, fish meal, urea, milorganite, and compost. For phosphorus: bone meal. For potassium: wood ashes (may raise the pH). In addition to the above-noted disadvantages of using organic fertilizers, it is difficult to use them singly because it is difficult to calculate proportions, so there are “recipes,” or blended products available prescribing how many parts of each material should be used in combination.

Find out how to convert an inorganic fertilizer recommendation to an organic one.
(http://pubs.caes.uga.edu/caespubs/pubcd/C853.htm)

Weed Control
Two types of weed-controlling mulches are loose and membrane. They should be biodegradable (not synthetic, such as plastic sheeting). Typical loose mulches include compost, bark and wood chips, shredded prunings, straw, buckwheat hulls, and cocoa shells. Membranes include newspaper, cardboard, and landscape fabric. Using any of these materials will inhibit weed seed germination by blocking sunlight. When using loose mulches they must be applied to a thickness of 2 – 4 inches.

Even with good preventive measures there will be some weed growth. Hoeing and hand pulling are both effective mechanical methods for removing weeds. It is best to weed when the weeds are small. If it is necessary to remove weeds from large areas use any of the following methods: (1) Turn the ground with a digging fork, spade, or digging hoe then cover the ground with a mulch membrane for a few weeks. (2) Cultivate with a rotary tiller although this process may have to be repeated several times because broken portions of perennial weed roots can regrow. (3) Cover the area with any light-excluding mulch for several months; mulch in the spring for fall planting and in the fall for spring planting.

Plant Disease Control
Organic gardening relies primarily on preventive, cultural, and integrated methods of pest and disease management. However, there are a number of materials and techniques that can complement and support organic management.

• Selecting a plant variety that has resistance or tolerance to insects or diseases makes it possible to avoid or lessen the use of pesticides or other management tactics.
• Beneficial insects such as predators and parasites are essential to preventing outbreaks of pest insect populations. Principles of insect pest management include:
• sustain natural enemies through the use of habitat manipulation
• avoid pests by using cultural practices
• when necessary, use rescue insecticide treatments or other practices that have minimal effect on beneficial insects to control the pests

• Plants respond to attacks by insects and diseases by mobilizing an array of compounds that inhibit plant diseases, or reduce feeding by insects. The application of mature composts to soil or potting mix has been shown to induce a resistance response in above-ground parts in several crops including cucumber and tomato. Microbial products that are sold for biological control of soil-borne root pathogens may also induce resistance to diseases of above ground parts. A number of compounds have been shown to induce resistance in plants when applied to the foliage.

Materials for control of plant disease include; the bacteria Bacillus subtilis and B. thuringiensis; the fungi Beauveria bassiana and Coniothyrium minitans; bicarbonate, copper products, and kaolin clay; synthetic and natural oils (petroleum, plant, and fish); botanicals: neem pesticides, pyrethrum, and rotenone; pesticide soap ( a synthetic); and spinosad, a microbial product derived by fermentation.

Useful Websites

Resource Guide for Organic Insect and Disease Management (Cornell University)

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