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The Basics of Garden Soil
Judge a site for your vegetable garden by weighing whether it has these key factors:
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- How do sunlight and shadows fall on the planting area?
- Is the planting site protected from prevailing winds?
- Is there level ground on which to plant, or are beds and terraces needed?
- What is the texture of the soil and is it easily worked?
- How is the soil’s drainage: fast, moderate, or slow?
- Will the site need improvements before planting is possible?
What Makes Good Soil for Vegetables?
Together with site conditions your garden’s soil is essential to growing great vegetables. In fact, many garden experts say soil condition is of the essence of successfully growing vegetables, and there’s lots of scientific data to support their position.
It may have taken 100 years or more for Mother Nature to produce each inch (25 mm) of the topsoil found in your yard or garden. When improving garden soil, patience is important to remember.
Good Garden Soil. Healthy soil is composed of many organic, mineral, and even living elements. It also contains microbes that digest and break down decaying plant matter into its components, making the food that growing vegetables need to thrive and prosper.
The top 6 in. (15 cm) of soil contain 80 percent of its beneficial microorganisms.
Major Soil Nutrients. The three most common nutrients found in garden soil are nitrogen (N), phosphorus (P), and potassium (K). Grouped together, they are often called the soil’s macronutrients.
Nitrogen is the only one of the three that’s water soluble and is necessary for foliage growth. Too little nitrogen stunts growth, while too much causes lush foliage growth at the expense of flowers, fruit, and seed.
Phosphorus, a common element found naturally in abundance in many soils, affects plant vitality and aids flower, fruit, and seed formation. Too much phosphorus limits the uptake of copper, iron, and zinc by plants, stunting their growth.
Potassium influences the growth of both stems and roots by influencing efficient protein and carbohydrate synthesis inside plant cells.
Your soil needs all three of these macronutrients. The amounts found in your soil depend on the minerals contained in the bedrock underlying your site.
Macronutrients are just part of the story, however.
Micronutrients and Trace Elements. More than 30 micronutrients and dozens of trace elements are found in most soils. Their presence or absence depends mostly on two factors: the quantity of decomposed organic material that the soil contains, and the maintenance of a proper acid-alkaline balance to break the ionic bonds of these compounds and free them for use by your plants.
Soil Texture. The best vegetable garden soil is loose, fertile loam with equal parts mineral clay, silt, and sand mixed with ample decomposed organic material, air, and water. In fact, ideal garden soil has roughly half of its total volume made up of air and water, while organics are 5 per cent and minerals are 45%.
Acidity and Alkalinity. Garden soil should have an acid-alkaline balance measuring 6.0–6.8 on the pH scale, a reading that is slightly acidic. This helps free mineral-bound nutrients so they can be absorbed by your vegetable plants.
Other Site Considerations
Vegetables need ample, strong light. Direct sun is best, eight to twelve hours during the peak growing season. Shadow and shade slow growth and fruit development from many vegetables, but especially long-season vegetables such as melons, squash, and corn.
Note the site’s wind exposure. Fences, hedgerows, and trees on the windward side of a garden help growth in areas with strong winds throughout the season. It’s best if crop rows align with the wind, rather than be broadside to them.
Is the site level, gently sloped, or on a hillside. It’s difficult to apply water evenly to plantings on slopes. In severely sloped sites, terracing may be necessary to hold the soil and irrigation water in place.
Is the mineral soil an even mix of fine silt, grainy sand, and larger particles? How much organic matter does it contain? Will water drain quickly down through it, leaving roots dry, or will they be standing in water until it is slowly absorbed?
What can you do to the site to correct any of these deficiencies?
You’ll learn that vegetables can be grown nearly everywhere, but they produce best and require the least care to stay healthy and strong in sites with favorable conditions.