Plants, like people, require adequate air, water, and food to live; and they need a balanced diet to be healthy. This includes not only basic nutrients, but also a wide variety of organic compounds, “micronutrients,” and trace elements found in many different foods. The best nutritional supplements you can buy (vitamins, minerals, herbal extracts, etc.) can help to make up for a poor diet, but there’s no substitute for “eating right.”
In nature, native plants get everything they need to grow and flourish from their environment. Healthy soil is the plants’ “food court,” the foundation and the source of a complete range of nutrients that are constantly being recycled and served up to the plants by countless microscopic organisms. Adding organic matter to the soil by grasscycling, mulching, and composting is the best way for people to re-supply the soil with natural plant food and keep the hard-working microbes happy. Grasscycling returns 60% of the nitrogen and 100% of the phosphorous and potassium (fertilizer ingredients) back to the soil. Just as importantly, these practices improve soil texture, allowing air, water, and nutrients to go deep into the earth to build strong and healthy root systems.
Sometimes, however, plants (like people) need extra help, especially when their growth is stunted by poor nutrition, or when they get sick because their natural immune systems have been weakened by dietary deficiencies. But it’s very important to know what’s wrong before prescribing a cure.
A Soil Test is a good first step in determining what your plants need to stay healthy.
Your local Texas AgriLife Extension office can provide you with information and supplies to take soil samples from your yard, and offers soil testing services for a small fee. A basic soil test covers soil pH (acidity/alkalinity) and the primary nutrients nitrogen, phosphorus, and potassium (NPK). For an additional fee, testing can be done for micronutrients, organic matter, and soil texture.
Soil Testing Links
- Aggie Horticulture – Soil Testing
- Texas A&M Soil, Water, and Forage Testing Laboratory
- Texas Urban Landscape Guide – Soil Analysis and Improvement
Most chemical fertilizers contain only the primary nutrients nitrogen, phosphorus, and potassium (NPK). When applied to compacted soils, nitrogen and phosphorus can wash off and travel through the storm sewer into lakes and streams, where they can create pollution problems. If not absorbed by plants and organic matter in the soil, they can also travel quickly through porous soils to pollute the groundwater. If you use chemical fertilizer, apply only half as much as the directions indicate, twice as often, to prevent the fertilizer from running off or leaching into our groundwater.
A study conducted by Texas A&M for City of Austin’s Watershed Protection and Development Review Department compared nine different fertilizers and found that the certified organic or other natural fertilizers out-performed the synthetic ones for both appearance and pollution prevention. Considering the results of this study along with other studies, scientific data and practical experience, a group of horticulturists and soil and water quality scientists reduced their recommendations for fertilizer use by at least 75%!
|If your soil test shows:||Use:|
|Low to Very Low Nitrogen in Soil||½ lb. nitrogen per 1,000
square feet twice a year
|Moderate Nitrogen||½ lb. nitrogen per 1,000
square feet once a year
|High to Very High Nitrogen||DO NOT FERTILIZE|
- If you must fertilize without a soil test, never apply more than a moderate nitrogen rate or fertilize more than once a year.
- Never fertilize before a rain – the fertilizer can run off and fertilize our creeks, not your lawn