What Is in Loamy Soil?

Properties

• Soil is a combination of solid organic and inorganic materials as well as pockets of space between those materials. The inorganic solid matter in garden soil is a mix of particles of clay, sand and silt. Whether a particle is clay, sand or silt depends on the physical size of that particle. Sand particles are the largest of the three, followed by the much smaller silt and even smaller clay.

Texture

• Soil texture describes the proportions of clay, sand and silt particles to one another. If the percentage of sand, clay and silt is roughly equal then it is a loam soil. Soil that is predominantly sand has a coarse texture. Soil that is predominantly made up of clay particles has a fine texture. Silt lies between the two, but is much closer to the clay texture than that of the sand. Loam's texture feels a little gritty with some residual smoothness when you press it between your thumb and forefinger.

Structure

• The amount of space between soil particles determines its structure. Sand’s large, oddly shaped particles leave large gaps when they touch. Silt’s smooth particles fit in tight against one another with few gaps. The gaps between particles are important because this is where water and air flow and the space through which the roots move when growing. The combination of large and small spaces in loam mean that roots have time to absorb water and nutrients without becoming oversaturated.

Test

• You can come to a close approximation of whether you have loamy soil without microscopic analysis by observing some general properties that your soil displays. Squeeze a tablespoon of soil with water into your hand. Roll the soil around your palm; you have soil with good consistency if it does not leave deposits on your hand. Press the ball together between your thumb and forefinger and draw it out in a ribbon. Loam typically yields a ribbon that holds together with little cracking.