Tile drainage is a process of removing excess subsurface water from a soil. Due to increased rainfall and prompted by higher land values and better crop prices, tile drainage has been accelerated in North Dakota. The increased rainfall and high water table also caused salinity to become a problem. Tile drainage is a promising way to control water table and reduce salinity for wet soils. At the present time, there is no official tally of the amount of tiled land in North Dakota. Therefore, the impact of tile drainage on the soil and water resources is also unknown. This project explores the possibility to control water table and evaluate the soil and water quality changes.

The test field is located in the Red River Valley at Fairmount, Richland County, North Dakota. The feasibility of subirrigation will be evaluated through a mass balance approach. Soil salinity assessment will be conducted once a year by a Versis 3100. Changes in soil chemical and physical properties will be determined by deep core sampling for SAR, EC, pH, ESP, and in-situ soil moisture sensors as well as piezometers for water table depth and quality monitoring. Water quality from the tile effluent and piezometers will be monitored and analyzed during the growing season. Crop yield will be determined in the control, drained, and drained/subirrigated plots.

The expected results from this project are to: 1.) determine the feasibility of using the tile drainage for subirrigation to enhance crop production in the RRV, 2.) evaluate the changes of the soil chemical and physical properties overlying the drained and drained/subirrigated areas compared to untreated areas, 3.) monitor drainage water quantity and quality, ground water depth and water quality in the drained, drained/subirrigatedm, and controlled areas, and 4.) determine the impact of moderate SAR irrigation water on the dispersivity and hydraulic conductiveity of soils near the drain tiles used for subirrigation.