The texture of the soil influences the movement of water and nutrients through the profile, and also affects root growth. You can determine soil texture in the field either by forming different shapes with moistened soil (Figure 1) or by feel (Figure 2). Textural class affects water holding capacity: a clay soil can store about 200 mm of available water per meter (soil depth), a loam can hold about 160 mm per meter, and a sandy soil can store about 60 mm per meter.
Process
Place approximately 1 tablespoon of fine, dry earth in the palm of your hand. Drip water slowly onto the soil until it approaches the sticky point, i.e. the point at which the soil just starts to stick to your hand. Next, form a ball about 2.5 cm in diameter. The extent to which the moist soil can be shaped by hand is indicative of its texture (See below).
Textural class
Use the figure below to identify soil textural class based on the shapes which can be formed using the moistened soil.
| Sand (A)* | Soil remains loose and single-grained; can only be heaped into a pyramid. |
| Loamy sand (B) | The soil contains sufficient silt and clay to become somewhat cohesive; can be shaped into a ball that easily falls apart. |
| Silt loam (C) | Same as for loamy sand but can be shaped by rolling into a short, thick cylinder. |
| Loam (D) | About equal sand, silt, and clay means the soil can be rolled into a cylinder about 15 cm long that breaks when bent. |
| Clay loam (E) | As for loam, although soil can be bent into a U, but no further, without being broken. |
| Light clay (F) | Soil can be bent into a circle that shows cracks. |
| Heavy clay (G) | Soil can be bent into a circle without showing cracks. |
| * The letter in brackets refers to the corresponding image in Figure 1 below. | |
| Figure 1. Determining soil textural class by forming shapes with the soil. | Figure 2. Method to identify soil textural class based upon feel. |
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(Method and drawings after Ilaco (1985)) |
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