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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #207498
Title: Sprinkler and surface irrigation effects on return flow water quality and quantity

Author
item Bjorneberg, David - Dave
item Westermann, Dale
item NELSON, NATHAN - KANSAS STATE UNIVERSITY

Submitted to: Proceedings of the Fourth Conference on Watershed Management to Meet Quality and TMDLs (Total Daily Maximum)
Publication Type: Proceedings
Publication Acceptance Date: 1/12/2007
Publication Date: 3/10/2007
Citation: Bjorneberg, D.L., Westermann, D.T., Nelson, N.O. 2007. Sprinkler and surface irrigation effects on return flow water quality and quantity. In: McFarland, A., Saleh, A., editors. Proceedings of the Fourth Conference on Watershed Management to Meet Quality and TMDLs (Total Daily Maximum Load) Issues: Solutions and Impediments to Watershed Management and TMDLs. March 10-14, 2007, San Antonio, Texas. p. 89-95.

Interpretive Summary: The Conservation Effects Assessment Project (CEAP) was initiated to document the effectiveness of conservation practices funded by USDA farm programs. A major conservation practice in the Upper Snake-Rock (USR) watershed in southern Idaho is the conversion from furrow irrigation to sprinkler irrigation. We compared the effect of irrigation system type on water quality and quantity at the watershed scale in six small watersheds (150-700 ha). These watersheds had 5 to 70% of the cropland sprinkler irrigated and the remaining fields surface or furrow irrigated. Other agricultural land uses, cropping practices and soils were similar among watersheds. Annual irrigation inflow to watersheds and annual outflow from watersheds did not decrease as the relative amount of sprinkler irrigated area increased. This probably results from the flow rate allocation system used on the Twin Falls irrigation tract. Annual sediment loss and concentration also did not correlate with the relative amount of sprinkler irrigated area. However, annual sediment loss and concentration correlated with irrigation inflow–the more irrigation water delivered to a watershed the greater the outflow sediment concentration and loss. Limiting analysis to July when irrigation demand is greatest, showed that increasing the relative amount of sprinkler irrigation in a watershed tended to decrease sediment concentration, total P concentration and soluble P concentration. These preliminary results indicate that irrigation water delivery should be managed in addition to converting to sprinkler irrigation to improve water quality in this irrigated watershed.

Technical Abstract: A major conservation practice in the Upper Snake-Rock (USR) watershed is the conversion from furrow irrigation to sprinkler irrigation. We compared the effect of irrigation system type on water quality and quantity at the watershed scale. Six small watersheds (150-700 ha) were identified with 5 to 70% of the cropland sprinkler irrigated and the remaining fields surface or furrow irrigated. Other agricultural land uses, cropping practices and soils were similar among watersheds. Water quality and quantity entering and exiting each watershed were measured with automated samplers during the irrigation season. Irrigation inflow to watersheds and outflow from watersheds did not decrease as sprinkler irrigated area increased. This probably results from the flow rate allocation system used on the Twin Falls irrigation tract. Annual sediment loss (r=-0.19, P=0.40) and concentration (r=-0.38, P=0.30) also did not correlate with the relative amount of sprinkler irrigated area. Annual sediment loss (r=0.87, P=0.03) and concentration (r=0.84, P=0.05) correlated with irrigation inflow–the more irrigation water delivered to a watershed the greater the outflow sediment concentration and loss. These preliminary results indicate that irrigation water delivery should be managed in addition to converting to sprinkler irrigation to improve water quality in this irrigated watershed.