Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/30/2006
Publication Date: 7/22/2006
Citation: Russelle, M.P., Busman, L.M., Niebur, J.L. 2006. Extending the reach of grassed waterways: perennial strips over tile lines reduce nitrate loss [abstract]. Soil and Water Conservation Society Proceedings, July 22-26, 2006, Kestone, Colorado. p. 29. Interpretive Summary:
Technical Abstract: Nitrate losses from subsurface drain tiles have been implicated in promoting hypoxia in the Northern Gulf of Mexico. Targeted management strategies may help achieve significant reductions in nitrate loss with minimum cost. Our hypothesis was that this goal could be achieved by growing narrow strips of deeply rooted perennial forages directly over tile lines. We tested this hypothesis in a field experiment on a Clarion-Nicollet-Webster soil association near Waseca, MN. Plots (23 m wide by 30 m long) of grass or alfalfa were established with central tile drains after installing diversion tiles through a set of established patterned, 13-cm diam. plastic tiles. These original tiles served as the undisturbed drainage system and ranged from 1.0 to 2.1 m deep. Calibrated tipping buckets measured water flow and grab samples of water were collected 2 or 3 times per week for nitrate. Established strips of alfalfa or grass did not alter annual tile water flow but may have increased 'flashiness.' Smaller nitrate-N concentrations in tile water were most apparent after the strips were well established and in plots with shallower tiles. Flow-weighted annual nitrate-N concentrations were higher for corn and soybean (15 mg N/L) than for the strips (4 mg N/L) during 2004 and 2005. In contrast to nitrate concentration, perennial strips reduced annual loss of nitrate-N more with deeper tiles. The land required to achieve specific reductions in nitrate loss varies with tile arrangement and spacing, but this targeted conservation practice appears to be practical, effective, and relatively low cost.