• Soil types vary across the United States.Michael Hitoshi/Photodisc/Getty Images
  
  Clay, silty, sandy and loamy soils--and their numerous combinations--can be found throughout the United States. Though certain soil types have often been associated with certain regions of the country (sandy in the Northeast, and clay in the Mississippi Delta, for example), you can find soils of nearly every type in most states. Each soil type has easily recognizable characteristics.
  
  

Clay

• Clay soils tend to crack when dry.clay image by Pavel Korsun from Fotolia.com
  
  Clay soils range in color from beige and brown to yellow, red and even blue. The color can be an indicator of characteristics such as texture, aeration and permeability.
  
  Clay soils are made up of fine particles up to 0.002 mm in size, according to the Microbiology Procedure website. On the positive side, clay soils hold moisture and nutrients well because of their density. On the downside, however, they can be viscous and sticky, allowing little air to pass through them when they are wet. This density is not good for plants because their roots need oxygen. In addition, water tends to adhere to the soil particles and is then unavailable to plants. This characteristic of clay soils may present problems to plant growers.
  
  Once clay soil dries out, it becomes hard and difficult to work. When clay soil cracks, it can actually tear the roots off plants or push them out of the ground.
  
  

Silt

• Silty soil is considered one of the most hospitable soils for plants, according to EAIS.net. With a particle size that ranges from 0.002 mm to 0.05 mm, it retains nutrients well and offers good aeration and drainage. in addition, silty soil holds moisture and is easy to work with, wet or dry.
  
  

Sand

• Sandy soils are known for their good drainage; however what's not as widely known is that the good drainage is the result of low organic content. Particle size can range from .05 mm to 2.00 mm, according to Microbiology Procedure. Sandy soil can be greatly improved via the addition of organic matter, such as compost or manure.
  
  

Loam

• Loam is a mix of clay, sandy, and silty soils in proportions most conducive to healthy plant growth, according to EAIS.net. It is composed of 40 percent silt, 40 percent sand and 20 percent clay. Loamy soil is packed with nutrients and offers ideal moisture retention. In addition, it drains well. Depending upon how the particles are situated -- that is, whether they are stacked one atop the other or are organized in an alternating pattern, which allows for more space between the particles -- it may manifest as clumps of sod or as more loosely structured soil that is easier to work.