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The Dirt on Soil

Garden Soil: Why it Matters - Making it Great


Soil is often viewed as the boring part of gardening. While garden soil will never be glamorous or even as interesting as choosing plants, there is a whole world under our Wellingtons that literally and figuratively is the foundation for our gardens. New gardeners are cautioned to put money and effort into improving their soil before they even consider planting, but few appreciate the wisdom in what they are hearing until they watch their new plants struggling for survival and demanding more and more food and water. In organic gardening, you learn to feed the soil and let the soil feed the plants.

The soil found in a typical yard will be about 90% mineral residue and only about 10% decayed organic matter. Yet it sustains a community of insects and microorganisms. The reason for adding additional organic matter to your soil is to provide food for the beneficial microorganisms that release nutrients into the soil as they decompose the organic matter. Earthworms and other soil dwelling insects aerate the soil as they move through it and contribute still more organic matter with their waste and decomposition. This makes for what is called healthy soil.

Pesticides sprayed on the plants will make its way into the soil and can kill the insects and microorganisms living there. Synthetic fertilizers contain salt, which can also kill the soil's residents as well as build up in the soil and cause harm to the plants you are feeding. And synthetic fertilizers add nothing to the soil's fertility.

What is Healthy Soil?

When discussing soil, we generally focus in on four things: texture, structure, pH, organic matter and fertility.

  1. Soil Texture

    Soil texture refers to the size of the soil particles.

    • Sand: Sand has the largest particles and they are irregularly shaped. This is why sand feels course and also why it drains so well. Sand doesn’t compact easily.

    • Silt: Silt particles are much smaller than sand, but still irregularly shaped.

    • Clay: Clay has microscopic sized particles that are almost flat. Clay packs very easily, leaving little to no room for air or water to move about.

    • Sandy Loam: Sandy loam is considered the ideal garden soil and consists of a mix of the three basic textures. However, don’t run out to buy sand to add to your clay soil or vice versa. Mixing sand and clay will give you cement. There’s more to the equation than just balancing soil textures.

  2. Soil Structure

    Soil structure refers to the way soil clumps together. You can usually determine what your texture is by testing your structure. Squeeze a handful of damp soil into a ball in your hand. If you poke the ball lightly with your finger and it breaks apart, it is probably sand. If a bit more pressure breaks it, you’re dealing with silt. If it sits there despite your poking, you have mostly clay. Do determine a more accurate reading of the percentage of each texture in your soil, try this easy experiment.

    A good soil structure is crumbly. This allows plant roots to work their way through it, air can pass through and water drains, but not so quickly that the plants can’t access it. If you’d like to test how well your soil drains, try this percolation test. (The second of the Four Easy Do-It-Yourself Soil Tests.)

    There are two basic ways to improve soil structure and they work in tandem.

    1. Soil dwelling insects. As mentioned earlier, insects moving about in the soil help to aerate the soil and they add small amounts of organic matter, the second structure improver.

    2. Organic Matter. Organic matter improves any type of soil. Compost, leaf mold, manure and green manures are all decaying organic matter. They loosen and enrich soil and provide food for the soil dwelling insects.

    You can loosen soil structure by tilling and sometimes this is necessary. But tilling can over crumble soil and it kills the insects living there. So regular tilling is not the best option.

Related Video
Adding Compost to Soil

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