Three different soil particles determine a soil’s texture. Sand particles are the largest, clay the smallest, and silt is in between. Medium-textured soils (loam, sandy loam, and silt loam) have a good mixture of sand, silt, and clay that is ideal for growing most plants. It is more difficult to grow plants in soils that contain an excessive amount of either clay, sand, or silt.
To evaluate your soil’s texture, lightly squeeze a handful of moist soil. If the clump crumbles apart, the soil is sandy. If it forms a sticky ball, it is clay. If the soil ends up as a spongy ball, you have loam.
Combining individual sand, silt and clay particles into larger clumps, called aggregates, creates soil structure. Good garden soil is crumbly. Nutrients and water are held within the aggregates. The spaces between aggregates allow water and air to move easily though the soil and provide enough space for plant roots to grow.
Plants grow best in soil with good structure. To maintain the structure, do not walk on, dig, rototill, or drive machinery over wet soil. Any of these actions can damage soil structure, compacting the pores, which decreases the movement of air and water through the soil.