There are four main types of soil found in agriculture: clay, silt, sand, and loam. Clay soil is made up of small, tightly packed particles that retain water and nutrients well. Silt soil is made up of larger particles that don't retain water and nutrients as well as clay. Sand soil is made up of coarse particles that don't retain water or nutrients well. Loam soil is a combination of clay, silt, and sand, and it is the most fertile type of soil.