Soil
 

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1. What Is Soil vs. Dirt?

DIRT

• Undesirable material out of place

• Mostly sand, silt, clay; may contain rocks

• Lacks minerals, nutrients, and living organisms

• No topsoil, humus, worms, fungi

• No texture or structure

• Does not compact when wet → leads to runoff & erosion

SOIL

• Contains nutrients, minerals, organic matter

• Alive with organisms: worms, fungi, insects, bacteria

• Supports plant life

• Made of sand, silt, clay, and organic matter

• Holds moisture and nutrients

• Provides anchoring for plants

2. Soil Composition

• 50% solids

  • Weathered geologic material

  • Minerals

  • Decayed plant/animal remains (organic matter)

• 50% pore space

  • Filled with air and water

  • IMPORTANT: Air and water cannot occupy the same space → when one increases, the other decreases
    → Overwatering = plant decline or death

3. Tarrant County Soil Types

• Cross Timbers – Sandy loam

• Grand Prairie – Clays, limestone, silty loam

• Blackland Prairie – Dark black to light grey clays

4. Common Soil Types & Traits

Sand

• Great drainage

• Poor at holding nutrients

Clay

• Holds nutrients well

• Poor drainage

Silt

• Erodes easily

• Moved by wind (dust storms) & water (floods)

Loam

• ~40% sand

• ~40% silt

• ~20% clay

• Ideal for most plants

5. Improving “Bad” Soil

Compost

• Add 2–3 inches

• Aerates and loosens clay

• Adds nutrients & organic matter to sandy soil

Expanded Shale

• Contains many air spaces

• Loosens tight clay and improves workability

⭐ Best clay amendment: Expanded shale + compost
(Recommended by Dr. Steve George, Texas A&M)

6. Soil pH Basics

• pH affects nutrient availability and plant health.

Examples

• Azaleas: acidic pH 5.0–5.5

• Blueberries: acidic pH 4.3–5.5

• Vegetables & most ornamentals: slightly acidic pH 6–6.8

• Clematis: neutral to slightly acidic pH 6–7

• Salvias: tolerate alkaline soil pH 6.1–7.8

Adjusting Soil pH

• To LOWER pH (more acidic): Add sulfur

• To RAISE pH (more alkaline): Add lime

• Gypsum = natural calcium + sulfur

  • Helps break up clay, reduces compaction

7. Native Plants

• You can’t change your yard’s native soil pH significantly

• But you can amend the soil to improve it

• Native plants perform better with local soil conditions

8. Watering Essentials

Hydrophobic soil

• Water repels instead of soaking in

• Common in dry, compacted, or organic-matter-poor soils

Best Watering Methods

• Cycle & Soak for lawns

• Infrequent, deep, slow watering

• Drip irrigation is better than spray (especially for gardens)

9. Importance of Mulch

• Conserves moisture

• Protects roots

• Limits weed growth

• Improves soil quality

• Regulates soil temperature

10. Healthy Soil Tips

• Add organic matter regularly

• Avoid overwatering

• Protect soil with mulch

• Select native/adapted plants

• Reduce compaction

• Maintain proper pH