The Dirt on Soil

By Christine Reid.

There’s an old gardening adage that declares, “It all begins with the soil.” It essentially means that when you water the garden, you’re really watering the soil, not the plants. And when you haul out the bag of fertilizer, you’re feeding the soil, not the plants. Successful gardening begins and ends with the soil. If the soil is no good, the garden will do poorly, no matter how fancy the seeds are, how perfect the weather is or how well you do everything else.

If a beginning gardener understands the following, they’ll be off to a great start. Soil (not dirt, not ground, not mud) is a living, dynamic system of medium and minerals. Healthy soil is a mix of organic matter, earthworms, insects and microscopic plants and animals. It is teeming with energy that helps trees and plants grow. Whatever you do and don’t do to the soil affects it, your garden, and when producing food, you.

The big question is, how does anyone know if their soil is healthy? One of the best and most efficient ways to gauge the condition of the soil is to have it tested. There are a number of soil testing labs in Texas and elsewhere that can tell you what your garden needs, if anything. Beyond finding out what’s in your soil, the test should reveal exactly what the plant can get from the soil. There can be all sorts of valuable nutrients in the soil but if they’re locked up for any reason, they can’t be used by your plants. A comprehensive test can save you money, time and grief by alerting you to possible mineral deficiencies or fertilizer overload. Dumping a bunch of soil amendments on your garden without a soil test is like taking large handfuls of vitamins and supplements without input from your health professional. People shouldn’t self-diagnose their health nor should they decide what their soil needs without information.

There are four major areas to consider when the goal is healthy, chemical-free garden soil. Soil structure, plant nutrients, organic material and soil biology all need to be in balance for the garden to produce the best results. 

Most people know in a general sense what kind of soil structure they have when it comes to the broad categories of sand, clay or silt. Many soils are a mix of the different types. Sandy soil is comprised of small rock and mineral particles and doesn’t hold water or nutrients very well. Clay is mostly made up of fine-grained minerals which can be elastic when wet or hard like a brick when dry. Silt has granular material in sizes between sand and clay. It holds water and air but needs amendments for fertility. There are natural ways to enhance and improve whatever soil is in your garden.

There are four groups of plant nutrients: primary, secondary, macro and micro. They’re all important but need to be in the proper amounts and need to be in a usable form. While clay soil, which many Hays County gardens have, can retain phosphorous and potassium, it can’t hold on to nitrogen, which doesn’t build up. The ratio of the three major nutrients are listed by number on every bag of fertilizer: nitrogen (N), phosphorous (P) and potassium (K). Secondary nutrients are calcium, magnesium and sulfur. A macronutrient is silicon; adequate amounts of silicon can increase some plants’ growth and can help plants from succumbing to fungal pathogens. Micronutrients are needed only in very small amounts: boron, copper, iron, chloride, manganese, molybdenum, selenium, sodium and zinc. 

Organic matter is extremely important. Without a continuous supply, soil will lose its nutrient balance and the quality of the food will suffer. Organic material can be fresh, decomposing and stable. All three types are necessary to have a vibrant, productive garden. Healthy soil with appropriate amounts of organic matter allows good root penetration, holds water better and reduces erosion.

Soil biology is made up of two parts: bacteria and fungi. These two things are what enable the plants to use the nutrients in the soil. Bacteria help transform inorganic particles from one form to another. What would we do without bacteria? By doing their thing, they provide plants with suitable forms of chemicals that help them grow. Fungi colonize the root zone of plants and provide nutrients to the plants in exchange for carbohydrates that the plants produce from photosynthesis. Fungi also help plants grow and withstand stress.

All this information can seem overwhelming but it’s important to remember that nature has been doing quite nicely on its own without synthetic fertilizers and pesticides ever since plants began growing on earth. In other words, emulate nature when preparing and maintaining a successful garden. Avoid the use of synthetic products that can kill beneficial insects as well as wreak havoc with the biological activity of the soil. Use organic products that are slow release, like nature, and only when necessary. Compost is good for any soil. Make and use your own to fertilize the garden and use natural mulch to retain moisture, suppress weeds and moderate the soil temperature. And keep in mind that anything that harms the earthworms in your garden has no place in a healthy gardening program!

Any questions? Send email to [email protected] or call (512) 398-6011.

These tips should help beginning gardeners get a leg up on spring:

• Pick a spot that gets 8 hours of direct sun and has appropriate drainage (start small)

• Have the soil tested at a professional soil testing lab such as Texas Plant and Soil Lab (www.texasplantandsoillab.com) 

• With test results as your guide, mix or till in compost, leaf and grass clippings and/or any necessary soil amendments to a depth of 6-12 inches or more (always know the source of your material) 

• Start a compost pile, if you haven’t already 

• Pick plants you like to eat and install them in the garden at the proper time with transplants or seeds

• After planting, water with rainwater, if available, and always water the roots deeply and only when needed 

• Use natural mulches to help retain moisture, suppress weeds and keep soil temperatures stable

• Allow beneficial insects and other wildlife to thrive by planting pollinator-friendly flowers and herbs and avoiding the use of synthetic and unnecessary pesticides (even organic ones) 

• Utilize organic Texas gardening resources at the county extension office, local libraries, nurseries and online guides