Building Soil Quality
Left to herself, Mother Nature creates "top soil" very slowly — about one inch per century — as the litter of leaves and other plant wastes fuel the dynamic ecology of soil organisms and chemistry.
You can assist nature and create healthy soil. Healthy, living soil will keep your plants happy and be the foundation for successful gardening and landscaping.
Soil testingFirst, test your soil to determine its acidity or alkalinity. This important measure is represented by a scale of numbers from 1 to 14 — called pH. A pH of 7 indicates neutral or balanced soil. Each higher whole number means 10 times more alkaline. Each lower whole number means ten times more acidic. You may need to adjust your soil pH depending on what you wish to grow.
Your county Cooperative Extension Service will test your soil with the help of a laboratory at the University of Florida in Gainesville. Costing $7, their written analysis will reveal your soil pH and existing amounts of major plant nutrients: nitrogen, phosphorous, potassium, calcium, and magnesium (N,P,K, Ca, Mg). Their report will advise pH amendment and fertilizer rates to favor the plants you indicated you wish to grow. A simpler analysis, showing only soil pH and amendment, costs $3.
Call your local extension office to order the soil testing bag and submission form. Then mail or drop off your soil sample with the Soil Testing Lab, University of Florida, Gainesville.
Or you can buy do-it-yourself soil test kits at garden centers and from catalogs. A low-cost electronic pH meter can measure soil chemistry quickly when its probe is inserted into the soil.
Amending soil pHAll this chemistry can be very important. For even if plant food is abundant in the soil, if the pH is wrong, plants may not be able to perform their own chemical reactions to take up the nutrients. Most vegetables and flowers will thrive in soils with a pH of 6 to 7. Potatoes and tomatoes need a more acidic soil. Azaleas and camellias also require acidic soil. Most native plants will generally be satisfied whatever your soil.
Powdered, agricultural lime or dolomite will make soil more alkaline or "sweet," as some people say. Wetable, powdered sulphur will make soil more acid or "sour."
Adding nutrientsEarthworms are important and affordable soil builders. Eating and excreting their way deep underground and then back to the surface, their soil processing increases nutrients available to your plants and tends to balance the soil pH. Unlike chemical fertilizer, earthworm castings will not burn plant roots. Earthworms and their co-workers consume and process leaf litter and other organic materials. The more humus in your soil, the more earthworms. Most organic gardeners have a good sense of humus.
To add humus to your lawn, mow rather than rake leaves. Persistent raking slowly removes this source of humus and thus starves the earthworms and their cohorts. If you mow your own lawn or have a lawn mowing service, leave the clippings where they fall. This will save time and improve your lawn. This is especially true if you fertilize your lawn. The clippings are where your fertilizer is going, so don't throw it away.
Salt-based fertilizers reduce soil humus and often over-stimulate plant growth. If you use these powerful chemicals, follow directions carefully. Over-application can do more harm than good.
To increase humus in your garden soil, mulch regularly and deeply with fallen leaves, grass clippings, rotted hay (don't use dry or baled hay, as it contains weed seeds), stable bedding, or compost. In the garden aisles and borders, where durability of the mulch will reduce frequent replacement, use pine needles or coarse wood chips. Wood chips are often available for free from your utility company or for a small delivery charge from tree trimming services.
Avoid the labor of turning compost piles by simply spreading mulch where you wish to build soil. Bottom layers of the mulch will decompose naturally while the surface remains attractive. Mulch promotes better drainage in heavy, clay-type soils. Mulch helps hold water in thin, sandy soils.
Organic farmers often plant cover crops of peas, beans, rye grass, hairy indigo, or other nitrogen-fixing, soil-building plants. These so-called "green manures" are tilled back into the soil, usually at the prime of their growth, to enrich the soil as they decompose.
Soil ecology is like forest ecology: diversity gives health, strength, and resilience to all your plants.
Building soil is part attitude and part details. It's not rocket science and yet, it is a lofty process.
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Copyright © 1998 by Southern Gardening