"Dig In" to the mystery of our Treasure Valley Soil

What is the mystery of soil in the Treasure Valley? Actually, it isn't mysterious at all if you're willing to "dig in". With a little bit of investigation, you can learn how simple soil really is, even in the Treasure Valley.

All soil consists of sand, silt and clay. "Soil texture" is the ratio of sand, silt, and clay in your soil. Soil texture can determine things like drainage, water retention and the amount of nutrients the soil can store.

"Sandy loam" contains more sand. "Clay loam" has a higher content of clay. "Silty loam" contains more silt than sand or clay. You're probably getting the idea. "Nice loam", has an even combination of sand, silt and clay and it's excellent garden soil. To understand your soil better, your can test your soil texture using your hands in the easy exercise below. You will need your hands, a shovel (to dig some soil), and some water.

1. Dig 6-12 inches into the soil. Moisten the soil with water if it’s dry.
   
2. Take a cup of soil from at least 6 inches below the surface.
3. Complete tests A and B below.
4. Test in several areas and different soil depths.

Test A

Rub some very moist soil between your fingers. Sand feels gritty like sand or sugar, silt feels smooth or silky like flour or dry cornstarch, and clay feels sticky like dough.

Test B

Squeeze soil into a ball, then pinch between your thumb and pointer finger. You are trying to get the soil to form a "ribbon" (see photo to the left). Sandier soil has a harder time forming a ribbon, while more silt and clay increase the ability of the soil to form a ribbon. Heavy clay soil will hold the ribbon shape up to a few inches.

An agricultural soil report from a laboratory will dive deeper and tell you your soil pH, organic matter percentage, mineral content, nitrate level, and soil texture. These all help in plant selection, watering needs, and overall health of plants.