Estimating Soil Texture

Ribbon and Feel Test

To describe how to test a sample texture, soil and its variations require standardized terms and methods of measurement. Texture generally refers to the size, distribution and proportion of the particles that make up the soil, and thus vary from place to place. The size of the particles can be classified as follows:

Gravel, sand, silt, and clay refer to relative sizes of the soil particles. Texture variation may help to explain differences in plant growth that can be traced back to soil fertility, which depends in large part upon the different proportions of particles. For example, as soon as a ground is identified as sand, this soil is likely to have low available water capacity, as opposed to an
increasing clay content in the soil profile that is associated with greater capacity to hold water. The more clayey soils, however, tend to compact and crust, thus restricting root depth and presenting a higher risk of water erosion. In total, a uniformly textured soil lacks balance, such as the ability to retain water, possess adequate aeration, and providing a suitable temperature regulation at the same time. On the bottom line, physical characteristics of a field fundamentallyaffect crop productivity.

Method

For testing your soil texture. you need the following equipment:

• shovel
• sample soil (no bigger than a golf ball)
• water (in a beaker or bottle)

Take a sample of soil with your shovel sufficient to fit into the palm of your hand. Moisten the soil with water and mold your sample to a ball. Knead it until the ball does not stick to your fingers.

Figure I:
Moist sample soil rolled into a cigarette shape?

Yes                                                                                    No
Loam or clay?                                                                    Silt or sand?
Form sample to a long and thin ribbon                                  Rub between thumb and forefinger
(as thick as half a pencil)                                                     grainy                                        not grainy
                                                                                         sand particles in your hand          Compress between thumb and forefinger
Yes                                                    No                           = loamy sand                               sticks to thumb                  not sticky
Loam or clay                                      = sandy loam                                                                = loamy silt                       = silt          
Squeeze out between                                                                                                           
thumb and forefinger                                                                                                        
and rub once or twice                                                                                                       
against a hard object
(such as a thumb nail)
very shiny           slightly shiny/
= clay                 not shiny
                          = clay loam, loam