Sand

• With a diameter of 0.5 to 2 millimeters, sand grains are the largest of the soil components. Sand grains tend to be bulky and irregularly shaped, which keeps the particles from fitting tightly together. The result is a loose, lightweight soil filled with large gaps. Water runs easily through sand and, as a result, sandy soils tend to be dry. Additionally, water-soluble nutrients are easily washed away, which can result in infertile soils; on the plus side, planting sites filled with loose, sandy soils are easy to dig.
  
  

Clay

• Clay particles are the smallest soil components; each speck is approximately 100 times smaller than the average grain of sand. In the garden, these tiny bits of dirt are often tightly packed together. The microscopic spaces between the particles hold water well; consequently, soils that are high in clay tend to be dense, wet and difficult to dig. Clay particles also bear a negative charge, which causes them to attract positively charged nutrients. While this increases the fertility of the soil, the heavy nature of clay tends to hinder plant growth as it is incredibly difficult for young roots to push through the nearly solid material.
  
  

Silt

• Silt particles are the medium-sized soil components; they are approximately 10 times smaller than the average grain of sand but considerably larger than specks of clay. Grains of silt look like miniature pieces of sand, though they tend to be more uniform in appearance. They are usually coated with a light layer of clay. Accordingly, silt soils behave like a combination of both sand and clay; they stick together and absorb water and nutrients, but they do not clump so tightly that they interfere with the surrounding vegetation's ability to grow.
  
  

Loam

• The best soils for gardening have a mixture of sand, silt and clay. These soils, called loams, hold water, absorb nutrients, drain effectively and are easy to turn. The ideal garden would contain soil made of 40 percent sand, 40 percent silt and 20 percent clay; however, most gardens are far from ideal. While there is not much that can be done to change the soil's consistency, the soil's general structure can be improved by incorporating organic materials, such as rotted manure or mature compost, into the garden each spring. Organic matter adds nutrients to the soil and binds individual particles together, improving water retention and soil texture.