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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #259808
Title: Soil and Nutrient Losses from Small Sprinkler and Furrow Irrigated Watersheds in Southern Idaho

Author
item Bjorneberg, David - Dave
item King, Bradley - Brad
item NELSON, NATHAN - University Of Kansas
item Lee, Joon-Hee

Submitted to: International Irrigation Show
Publication Type: Proceedings
Publication Acceptance Date: 10/21/2009
Publication Date: 12/2/2009
Citation: Bjorneberg, D.L., King, B.A., Nelson, N., Lee, J. 2009. Soil and Nutrient Losses from Small Sprinkler and Furrow Irrigated Watersheds in Southern Idaho. Proceedings of the International Irrigation Show, December 2-4, 2009, San Antonio, Texas. p. 1-10.

Interpretive Summary: Sediment and associated nutrients flowing to the Snake River with furrow irrigation runoff and unused irrigation water have been a concern in the Twin Falls irrigation tract in southern Idaho. Converting furrow irrigated fields to sprinkler irrigation is one practice that has been promoted, and received financial assistance, to reduce sediment loss. Five small watersheds (330 to 1480 acres) with 10 to 70% sprinkler irrigation were monitored from 2005 to 2008 to determine if converting to sprinkler irrigation reduced sediment and nutrient losses from these watersheds. Eliminating runoff from furrow irrigated fields by converting to sprinkler irrigation will reduce sediment and nutrient losses from fields. However, there were no significant correlations between the amount of sprinkler irrigation and the sediment or nutrient loads from these watersheds. Potential reasons for these results are the flow rate allocation system used by the irrigation district, the amount and location of furrow irrigated fields in each watershed, and the management of furrow irrigated fields within each watershed. However there was a trend for dissolved phosphorus concentrations to decrease as the relative amount of sprinkler irrigated land increased in each watershed, presumably because less water flowed across fields in furrows as sprinkler irrigated area increased. A water quality model for irrigated watersheds is needed for more thorough assessment of the variety of conditions and management practices within these watersheds.

Technical Abstract: Sediment and associated nutrients flowing to the Snake River with furrow irrigation runoff and unused irrigation water have been a concern in the Twin Falls irrigation tract in southern Idaho. Converting furrow irrigated fields to sprinkler irrigation is one practice that has been promoted, and received financial assistance, to reduce sediment loss. Five small watersheds (330 to 1480 acres) with 10 to 70% sprinkler irrigation were monitored from 2005 to 2008 to determine if converting to sprinkler irrigation reduced sediment and nutrient losses from these watersheds. Eliminating runoff from furrow irrigated fields by converting to sprinkler irrigation will reduce sediment and nutrient losses from fields. However, there were no significant correlations between the amount of sprinkler irrigation and the sediment or nutrient loads from these watersheds. Potential reasons for these results are the flow rate allocation system used by the irrigation district, the amount and location of furrow irrigated fields in each watershed, and the management of furrow irrigated fields within each watershed. However there was a trend for dissolved phosphorus concentrations to decrease as the relative amount of sprinkler irrigated land increased in each watershed, presumably because less water flowed across fields in furrows as sprinkler irrigated area increased. A water quality model for irrigated watersheds is needed for more thorough assessment of the variety of conditions and management practices within these watersheds.