• Prairies in Louisiana have high soil organic matter content.prairie image by laurent gehant from Fotolia.com
  
  In the state of Louisiana, there are 11 Major Land Resource Areas (MLRAs), which are portions of the landscape categorized based on their terrain, underlying geology and soils. Within each MLRA, there are more than one soil type, and many of the MRLAs share similar soil characteristics, but differ based on the location on the landscape and their underlying geological formation. Some of the defining characteristics of soils are their age, how they were formed and their nutrient status.
  
  

Northern and Central Louisiana

• Northern Louisiana is comprised of portions of the Southern Mississippi River Alluvium, the Red River Alluvium, the Southern Mississippi Valley Loess, the Arkansas River Alluvium and the Western Coastal Plain. Along the rivers, dominant soils are vertisols, entisols, inceptisols and alfisols. Vertisols are soils that swell and shrink as they change between wet and dry. Entisols are relatively new soils that lack defined soil horizons that are evident in older soils. Entisols are common in river floodplains because the soils become deposited on the landscape as water flows over the banks of the rivers. These soil orders are further broken down into many different series, which vary based on soil moisture, clay content and pH.
  
  

Coastal Louisiana

• The MRLAs along the coast include the Southern Mississippi River Alluvium, the Southern Mississippi Valley Loess, the Gulf Coast Prairies and the Eastern and Western Gulf Coast Flatwoods. These areas share some of the same soil orders found in the northern and central part of the state, but also include histosols, which are waterlogged soils, consisting mainly of undecomposed organic matter. Spodosols and mollisols are both soils that are high in organic matter and are common in prairies.
  
  

Gulf Coast Marshes

• Along the coast of the state, adjacent to the Gulf of Mexico, are the Gulf Coast Marshes. This MRLA is over 8,000 square miles, and approximately 95% of it is in Louisiana. The soils there are entisols and histosols, which are both common in areas receiving sediment loads from river flooding. Histosols are common to many wetlands, especially coastal wetlands where undecomposed plant material makes up the majority of the soil profile.