Maintaining good quality soil is the best thing you can do for your gardens and lawn. Healthy soil means healthy plants, and that helps choke-out weeds. Good-quality soil retains water better, which means less time spent watering. It also holds nutrients, so you won’t spend as much time and money on fertilizers.
Soil composition varies widely across Texas. Most soils in the Dallas-Fort Worth area are alkaline clay. Soil type can vary even within counties, though, so always base your amendments on the soil specific to your location. Amending soil is something you can do for gardens that are planted and growing, as well as before planting new gardens or seeding a new lawn.
Testing Soil
To a certain extent, you can analyze soil yourself at home and amend based on your soil observations. Soil that does not drain well, packs tightly, and feels slippery when wet is mostly composed of clay. Soil that drains quickly and has a rough, gritty texture is sandy soil. Soils with in-between textures are sandy-loam, loam, or loamy-clay.
For a more exact soil analysis, send a soil sample to a testing lab. One of the most widely used in the state is at Texas A&M University. Another option is the Texas Plant & Soil Lab in the Rio Grande Valley. Professional soil tests will tell you exactly what type of soil you have, the percentage of organic matter it contains, and soil pH. Some tests will also analyze mineral content and provide guidelines for amending the soil.
Soil Goals
When you amend soils for most plants, especially in vegetable gardens, you want to create soil with a loamy texture. Loam soils have good drainage, retain moisture and nutrients, and don’t compact too easily. Some types of ornamental plants are better adapted to clay or sandy soils, but loam soil is ideal for most gardens.
Changing soil pH is a more challenging soil amendment goal. For soils that are too acidic, you can amend with dolomitic limestone and calcitic limestone to raise the soil pH. For overly alkaline soils, which are more common in central Texas, lowering soil pH can either be accomplished with sulfur or more slowly with organic additives like pine needles, pine bark, and peat moss. Plants that prefer acidic soil, such as azaleas, may have trouble growing in the Dallas-Fort Worth area without significant soil amendment.
Amendment Guide
Compost is the best all-around soil amendment. It improves the texture of all soils, adds nutrients, and helps buffer the soil pH. Compost from organic yard waste and from decomposed farm animal manure works equally well. Most compost has a pH between 7 and 7.5. If you want a more acidic pH to help counteract alkaline soil, choose horse manure or bark compost.
When you’re amending a new planting location, spread 3 to 6 inches of compost over the soil surface. When amending established garden beds, use 1 to 2 inches. If your soil is clay, use the higher amount of compost and if the soil is more sandy use the lower number.
Use a garden tiller to work the compost into the top 6 to 8 inches of soil. You can repeat applications of compost this way every year for vegetable and flower gardens you replant yearly. For established perennial gardens, spread the compost on the top of the soil around the plants like a mulch. If you’re putting compost on an established lawn, lightly rake a 1/4 to 1/2 inch layer of compost across the surface and then water it in.
