Tuesday, November 6, 2007
199-6

Measuring Water Table Depth in Loamy Soils in the Lower Mississippi Valley.

Edgar Mersiovsky1, Reed Cripps2, Jimmie Richardson3, and Cathy Seybold1. (1) USDA-NRCS, USDA-NRCS/Soil Science, 700 W Capitol Ave/Rm 3416 Fed Bldg., Little Rock, AR 72201, (2) 3407 South Caraway Road Ste 5, USDA-NRCS, USDA/NRCS, Northeast Area Office, Jonesboro, AR 72404-9556, (3) Centennial Mall N Rm 152, Natural Resources Conservation Ser., USDA-NRCS, MS 34100, Lincoln, NE 68508-3866

The USDA-NRCS is conducting a study to monitor seasonal water tables in soils within MLRA 131A, Southern Mississippi River Alluvium. Previous studies have suggested that the redoximorphic features in soils within loamy family particle size classes may be relic. Initially, soils along the Mississippi River Meander Belts as mapped by Roger Saucier are being studied. Soils with family particle sizes of fine-loamy, fine-silty, or coarse will be considered. The objective of this study is to collect soil water data for soils and landform positions throughout the Lower Mississippi Valley in a comprehensive and uniform manner. Collected data will be used to assist in populating the NASIS database and to refine interpretations affected by soil water data. The Dundee Series (Fine-silty, mixed, active, thermic Typic Endoaqualfs) will be studied first. Data within NASIS shows that the water table can be within 0.5 foot of the surface. The Official Series Description shows that in drained areas the water table is below 4 feet. Fourteen (14) sites throughout MLRA 131A along the meander belt of the Mississippi River are being monitored. At each site, three (3) piezometers are installed. Automatic Waterlogger-15 units from Global Water are installed in 2-inch PVC pipe. The shallowest is installed at the contact with the argillic horizon, to see how much of an influence the argillic horizon has with water movement. The second piezometer is placed within the argillic horizon to see if this layer becomes saturated. The third is placed at least 2 meters (m) below the surface. This piezometer will assist in determining how high the water table rises within the soil. As more data is collected, this depth will be refined to indicate the water table status in the soil. IRIS tubes will be installed at selected sites to determine if reduction is taken place.