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Internal drainage through fine-textured subsoils at two sites in North Dakota
- To determine if the internal drainage (downward movement of water out of the root zone) was adequate, we measured the movement of water out of the root zone in bordered plots planted to alfalfa. We applied three water quantity treatments: irrigation plus precipitation equal to one, two, and three times the calculated evapotranspiration (1 ET, 2ET, and 3ET); and two irrigation water quality treatments: electrical conductivity (ECiw) of 0.1 S/m, and sodium adsorption ratio (SARiw) of 4 and ECiw = 0.34 S/m, SARiw = 16. Each treatment was replicated three times. Internal drainage amounts during the irrigation season (1 July to about 1 October) were as great as 843 mm. For the seven years at one site, the internal drainage averaged 585 mm, or 66% of the water applied (irrigation plus precipitation) to the 3ET treatment. Increased water application resulted in increased internal drainage. Irrigation with the 0.34 S/m water resulted in greater internal drainage (compared to irrigation with the 0.1 S/m water) at one site, but not at the other site. The 3ET treatment maintained soil water content near field capacity for the entire irrigation season, but a persistent perched water table was not detected. Internal drainage from the 3ET treatments exceeded the total water applied (irrigation plus precipitation) to the 1ET plots for 9 of the 12 site years. The tested soils have sufficient internal drainage capacity to allow supplemental irrigation without forming a perched water table.
Trooien, T.P. , Wienhold, B.J. , Reichman, G.A.
glacial till soils , Medicago sativa , internal drainage , subsoil , irrigation water , water quality , rain , water table , evapotranspiration , soil texture , irrigation rates , North Dakota
- Includes references
- Transactions of the ASAE Mar/Apr 1996. v. 39 (2)
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.