Location: Northwest Irrigation and Soils Research
Title: Reducing nutrient losses in runoff from furrow irrigation Authors
Submitted to: Western Nutrient Management Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 10, 2013
Publication Date: March 7, 2013
Citation: Lentz, R.D., Westermann, D., Lehrsch, G.A. 2013. Reducing nutrient losses in runoff from furrow irrigation. In: S. Pettygrove (ed.), Western Nutrient Management Conference Proceedings, March 7-8, 2013, Reno, Nevada. Vol. 10. p. 60-66. Technical Abstract: Few studies have comprehensively examined nutrient losses in runoff from furrow-irrigated fields, but the rising cost of fertilizer and finite nature of the resource encourages further research. A 2-yr experiment measured runoff losses of sediment, particulate P and N, and dissolved NO3-N, NH4-N, K, and reactive P (DRP) from fertilized, manured, or non-amended fields. Average nutrient losses were substantial, including 15.6 lbs ac/yr dissolved N, P, and K and 73.6 lbs ac/yr particulate N and P. The cost or replacing these nutrients with inorganic fertilizers was not trivial, at $54.69 ac/yr. Relative to non-amended soil, manure increased dissolved K, NO3-N, and DRP in runoff by 2.1x, 1.5x, and 2.7x, respectively. Other experiments evaluated the influence of furrow management practices on runoff nutrient loads from soils amended with manure in late summer and irrigated in the fall or following spring. We measured sediment, dissolved NO3-N, NH4-N, DRP, and TP concentrations in irrigation furrow runoff. Delaying the first irrigation until spring or treating the fall irrigation with polyacrylamide (WSPAM) reduced runoff component losses by 80 to 100% relative to Fall-Controls. In the spring irrigation, moldboard plowing reduced runoff DRP mass losses by ~60% compared to rototill. The buried lateral furrow system decreased runoff mass losses for sediment, DOC, and TP by >80% relative to conventional irrigation. This research demonstrated that several management practices may be successfully employed to substantially reduce offsite nutrient transport during the first irrigation on furrow-irrigated, manure-amended fields.