Definition: The relative content of particles of various sizes, such as sand, silt and clay in the soil.
Soil Texture in the Forest Garden:
Soil texture is a classification of the soil's physical properties specifically particle size and where it comes from, rather than chemical properties that make up its nutrient contents. Soil's physical properties can affect the ability of the soil to hold nutrients and water, making the two interconnected. Texture also influences the ease with which soil can be worked, the amount of water and air it holds, and the rate at which water can enter and move through soil.
Most soils are a mix of three main mineral particles: sand, silt, and clay. The proportion of each determines the texture - how it feels, how it holds water and nutrients, and how it should be managed. The particle size matters because the amount of space between particles influences how things move through them.
Clay particles are the smallest and, as a result, bind together closely and can become compacted. This leads to heavy, unaerated soil, that does not drain well, causing water to rest at the surface rather than infiltrating. Sand particles are the largest, so soils with a high proportion of sand particles have a lot of space between particles. As a result, water flows through this soil very quickly and the soil has trouble retaining water and nutrients. Silt particles are a size in between sand and clay.
Forest Gardeners aim to find a good balance of this mix, called loam, when preparing nurseries and planting holes. It is dark in color, soft and crumbly in your hands. It holds water and nutrients well, but also allows for drainage and movement of air between soil particles and through the root zone.
It is important to recognize that soil texture is very malleable. Many of the techniques employed through the Forest Garden approach help shift soil from less desirable textures to more desirable textures through the addition of organic matter, beneficial microorganisms, and aeration.