Determining Soil Type

Soils are classified based on their content of the soil particles silt, sand, and clay. Each of these particles have different sizes and different moisture retention properties.

• Sand is 0.05 - 2 mm and retains very little moisture.

• Silt is 0.002 - 0.05 mm and retains moderate moisture.

• Clay is smaller than 0.002 mm and retains high moisture. 

The ratio of these particles determines the soil type as illustrated by the below diagram.

Finding out your Soil Type

The most accurate way to determine soil type is to have a sample tested in a laboratory. If this is not possible, some other basic methods are available:

1. Use a land information database
   If you are in New Zealand

   • Register for S-MAP Online, a free land database. 

   • After signing in, click on the "Locate Me" option.

   • Click on the soil summary icon

   • Click on the map in the position where your Wildeye will be installed.

   • You should now see the soil type in the "Soil Summary" section.

     

2. The Squeeze Test
   Grab a small handful of the soil in your hand and compress it in your fist. Ensure the soil is damp, but not soaking wet.

   • If the soil is sticky and slick to the touch and remains intact and in the same shape when you let go it is clay soil.

   • If the soil feels spongy it’s peaty soil; sandy soil will feel gritty and crumble apart.

   • Silt soils will feel smooth textured and hold their shape for a short period of time.

3. The Settle Test
   Add a handful of soil to a transparent container, add water, shake well and then leave to settle for 12 hours.

   • Clay & silty soils will leave cloudy water with a layer of particles at the bottom.

   • Sandy soils will leave the water mostly clear and most of the particles will fall, forming a layer on the base of the container.

   • Peaty soils will see many particles floating on the surface; the water will be slightly cloudy with a thin layer at the bottom.

   • Soils that are chalky will leave a layer of whitish, grit-like fragments on the bottom of the container and the water will be a shade of pale grey.

   • If the water is quite clear with layered particles on the bottom of the container with the finest particle at the top – this soil is likely to be a loamy one.