How to Do a Soil Survey

January 23, 2025 Bill Hageman

Understanding Your Soil

Soil is the foundation of organic gardening. To ensure your garden thrives, it's important to know your soil's texture and drainage. Soil texture refers to the particle sizes that make up your soil: sand, silt, and clay. Each type affects how water and nutrients are retained, which directly impacts plant health.

DIY Soil Texture Test

To identify your soil texture at home:

Gather a clear quart jar, water, and 3 tablespoons of non-sudsing detergent.
Crush soil clods, measure 1 cup of soil, and add it to the jar.
Fill the jar two-thirds full of water, add detergent, and shake vigorously for 5-10 minutes.
Let the jar sit for 24 hours. Mark the sediment layers (sand, silt, clay) to identify your soil's composition.

Determining Drainage with a Percolation Test

Understanding your soil's drainage is key to knowing how water moves through it. To perform a percolation test:

Dig a hole roughly the size of a 5-gallon bucket.
Fill the hole with water and let it drain. Refill it, measure the water level, and check again after an hour.
A rate of 1-2 inches per hour indicates well-drained soil. If it takes over 24 hours to drain, the area has poor drainage.

How Soil Texture Affects Watering

Water retention varies by soil type:

Sandy soils: Hold 0.05 inches of water per inch of soil depth. Use high-flow emitters with frequent watering for effective irrigation.
Clay soils: Hold 0.17 inches of water per inch of soil depth. Use low-flow emitters over longer durations to prevent runoff.
Loam soils: Hold up to 0.18 inches of water per inch of soil depth. Water similarly to clay soils.

Why Soil Knowledge Matters

Knowing your soil type helps you decide where to plant, how much irrigation to provide, and the best fertilization practices. Understanding your soil ensures water and nutrients are used efficiently, saving resources and promoting healthy plants.