The soils of the lower Mississippi Flood Plain are derived from the Mississippi or Red River depositions. In certain areas these have been mixed. The soil constituents have been modified or changed entirely by time and environment.
Profiles from the Iberia, Buxin, and Baldwin soil series were studied. The comparative results indicate that the Iberia was highest in exchangeable calcium and base saturation. Exchangeable magnesium and potassium were highest in the Buxin. Baldwin was lowest in total cation exchange.
The Buxin series contained larger quantities of the oxides of iron, aluminum, magnesium, potassium and sodium as shown by analysis of the clay fraction than Iberia or Baldwin. Iberia was highest in calcium oxide and Baldwin highest in silica. The content of silica increased with depth for all profiles.
The ratios of SiO2/R2O3, SiO2/Al2O3, SiO2/Fe2O3, SiO2/total bases, and carbon-nitrogen varied with the soil series, depending upon the source of materials.
X-ray patterns indicate that montmorillonite and illite were the predominating clay minerals and varied with the particular series. The Iberia clay contained more montmorillonite than the Baldwin or Buxin, especially in the A and B horizons.
The characteristic study of these series has been of value in establishing fundamental facts that can be used in soil classification. It is evident that these series generally differ in chemical and mineralogical properties; yet, certain similarities exist between certain profiles of different series.