Mississippi Land Resource Areas
More than 400 individual soils are mapped in the state. They are described and classified by the Natural Resources Conservation Service. Information and data by query are publicly available at the Web Soil Survey https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.
Southern Mississippi Valley Alluvium: The Delta
Soils of the Mississippi Delta originate from sediments left by flooding of the various rivers in the region. It is not a traditional delta fan formed at the mouth of a river.
Most Delta soils are farmed, with three-fourths of this cropland in the northern part of the region. Controlling surface water and drainage are major soil management issues.
Soils are naturally diverse in the Delta due to their alluvial origin; the sediment originated north of Mississippi. Soils closer to running water have proportionally more large silt and sand particles (coarser texture) than soils further from the stream (clays).
Another factor in Delta soil formation is whether water on the surface moved or not. Soils formed under standing water have different properties than soils formed under running water.
Clay soils have unique features. Small, round aggregates form at the surface when they dry. These aggregates look like shotgun buckshot, hence the popular name for Delta clay soils: “buckshot.” Large amounts of clay in soil reduces water infiltration rates, which facilitates catfish and rice production in the region.
Southern Mississippi Valley Uplands: Brown Loam Hills and Thin Loess Areas
When floodwaters receded in what is now the Delta, strong west to east winds blew dry sediment left by flooded rivers to the adjacent uplands. The deposited material is called loess and is the parent material of soils formed in the hilly region along the eastern edge of the Delta.
The depth of loess decreases from west to east across the state as the distance from its origination increases. This area, known as the Brown Loam or Bluff Hills, has some very deep loess deposits as can be seen by the bluffs outside Yazoo City. Natchez silt loam is the Mississippi state soil. See these sites for more information: https://soilseries.sc.egov.usda.gov/OSD_Docs/N/NATCHEZ.html and https://casoilresource.lawr.ucdavis.edu/see/#natchez.
Coastal Plain soils in Mississippi are part of an arc along the United States coast from New Jersey to Texas. They form on unconsolidated fluvial or marine sediments deposited on the edges of ancient seas. These diverse soils are usually best suited to pastures and forests.
The northern portion of the Coastal Plain is commonly called the Mississippi Sand Clay Hills. The southern Coastal Plain is the “Piney Woods” region of the state.
There are two “Blackland Prairies” in Mississippi. One is in northeastern Mississippi in the Tupelo, Aberdeen, and Columbus area. Another, smaller one is in and near Scott County in south-central Mississippi.
Many of these soils are very dark, like Midwestern prairies. However, the Mississippi prairies form in soft limestone or chalk parent material in humid conditions. Conversely, Midwestern prairie soils form in glaciated areas predominated by grasslands under drier, less humid conditions.
Gulf Coast Marsh
There are zones of marsh along the Gulf of Mexico that differ from the rest of the state. It is almost treeless, has marsh vegetation, and is uninhabited. It is part of the estuarine complex that supports Gulf marine life.
Most Gulf Coast Marsh soils are very poorly drained, and the water table is at or above the surface most of the time. These soils are susceptible to frequent flooding. They formed in alluvial and marine sediments and organic accumulations.
Eastern Gulf Coast Flatwoods
The area between the marshes and the Coastal Plain is chiefly forest. Pulp and paper companies and the military have large holdings in the region.