Interest in organic gardening—using organic and natural materials for fertilization and disease and insect control—is increasing.
Much of the interest is on reducing or eliminating use of man-made pesticides for controlling insects and diseases. There is less interest in the use of natural and organic fertilizers.
Organic gardening in Mississippi faces some serious problems with the rapid loss of soil organic matter and severe insect and disease pressures on vegetable plants. Organic gardeners, to ensure the greatest chances for success, should have the garden soil tested for pH and nematodes.
The most beneficial input for both organic and conventional gardeners is to add organic matter to the soil. This can be done by adding composted or fresh organic materials and incorporating them into the soil. Gardeners need to pay attention to the amount of nitrogen in the materials they are adding. Straw; fallen, dried leaves; sawdust; wood chips; and paper should be blended with a high nitrogen material like grass clippings, manure, or blood meal since incorporating large amounts can actually keep the nitrogen in the soil from the crop plants while decomposing. The nitrogen becomes available again after decomposition is through.
Soils with a low pH (acid) can be corrected using limestone, ground oyster shells, wood ashes, or dolomitic limestone. Adding organic matter benefits soils with a high pH (alkaline).
Animal manures are the most widely used organic fertilizers. Unfortunately, their composition varies with the source, age, degree of rotting, water content, and amount and kind of litter used.
Green manures and cover crops can also be used to provide nutrients. When allowed to grow over the winter, hairy vetch or crimson clover can fix up to 100 pounds of nitrogen per acre. Southern peas can be grown during summer to provide nitrogen for fall vegetables. Green manure crops should be mown and plowed into the soil at least four weeks prior to planting the next crop.
Most organic materials do not contain plant nutrients in balance with plant requirements and must be supplemented to correct these imbalances. A well-leached animal manure has an estimated fertilizer value of 1-1-1, or 20 pounds each of N, P2O5, and K2O per ton of manure. Besides being relatively low in nutrient content, the nutrients are available more slowly than nutrients from inorganic sources. This protects nutrients from leaching, but when a rapid change in nutrient level is needed, this can be a problem.
Controlling diseases and insects by natural means alone is difficult. There are several insecticides available including Bt formulations for caterpillar control and spinosad or pyrethrums for other insects, but disease control is difficult. Neem oil, bicarbonate, and copper- and sulfur-based fungicides provide some protection against diseases, but the best results for disease management come from selecting resistant varieties and proper timing and spacing during planting. For these reasons, organic gardening is easier on a small scale.
Nutrient Content of Organic Materials
|Rock Phosphate||0||20 to 30||0||very slow|
|Bone Meal||1||15||0||slow medium|
|Compost||up to 3||1||1||slow|
|Dried Blood||12||1.5||.5||medium rapid|
|Cotton Seed Meal||6||3||1.5||slow medium|
|Cow Manure, fresh||.25||.15||.25||medium|
|Wood Ashes||0||1 to 2||3 to 7||rapid|
To increase chances for success, organic gardeners should follow these practices:
- Plant disease- and nematode-resistant varieties.
- Use marigolds, mustard, solarization, and organic products like Clandosan 618 to control plant parasitic nematodes (see Extension Publication 483 Nematode Control in the Home Garden).
- Plant seeds from disease-free plants.
- Plant only healthy vegetable transplants.
- Place a cardboard collar around plant stems at ground level to prevent cutworm damage.
- Incorporate plant residues and animal manures early to allow sufficient time for them to decompose before planting.
- Use mulches to control weeds and keep soil from splashing onto the plants and fruit.
- Use aluminum foil or reflective plastic mulches to repel aphids and thrips that injure plants and also transmit plant viruses.
- Plant as early in the spring as possible to avoid some insect problems.
- Keep the garden free of weeds that may harbor diseases and insects.
- Hand-pick insects.
- Water so plants are not wet at nightfall.
- Remove diseased plants and plant parts from the garden.
- Control insects using biological controls and natural products.
- Rotate garden areas.
- Encourage natural insect predators. Trap slugs under boards and moist burlap laid on the ground, or use beer traps.
- Stay out of the garden when the plants are wet to prevent spreading diseases.
- Do not use tobacco products while working in the garden.
- Mix different vegetables in a row to eliminate monocultures and the chance for a disease to spread rapidly.
It’s been an overall mild and rainy summer so far. If you’re like me, there no complaints with the mild weather. Mississippi is notorious for hot, humid summers so I’ll take slightly cooler temps any day of the week! July is a busy month in your yard and garden. Here are a few things to accomplish this month:
Do you have fire ants in your vegetable garden? Me too. Good news for all of us! There are some fire ant baits that are safe to use around food plants.
There’s nothing more satisfying than homegrown tomatoes. You don’t have to be a gardening expert to grow delicious tomatoes in your backyard. Here are a few tips that will help you grow the best looking (and tasting) tomatoes out there:
One of my favorite things to do during summer is ride around town and look at all the flowers planted in front of businesses and homes. A lot of work goes into having a nice landscape, so give yourself a pat on the back. Don’t let the heat deter you from continuing to maintain and grow your garden. Be sure to grab a bottle of water when heading outside in the Mississippi summer! Here are a few tasks to tackle during the month of June:
With the summer season fast approaching, I’ve been getting questions about fertilizing, primarily concerning the types of fertilizer and how much to use.I’m glad to get these questions because garden and landscape plants need fertilizer to keep them healthy and growing. Fertilizing at planting helps trees, shrubs and flowering plants get established. It also promotes shoot and root growth, flowering, and optimum fruit and vegetable harvest.