Submitted to: Animal Production Systems and the Environment
Publication Type: Abstract Only
Publication Acceptance Date: 7/19/1998
Publication Date: N/A
Technical Abstract: Surface tile inlets are a major conduit for transporting sediment, phosphorus, and nitrogen into tile lines in Southern Minnesota. Concern exists that manure applications could contribute additional loading of nutrients into tile drainage systems. We quantified the impact of manure vs. inorganic fertilizer (urea)on runoff and tile line water quality under two tillage systems (moldboard plowing and ridge tillage). The study was conducted on a Webster clay loam at the Southwest Experiment Station, Lamberton, MN. Ridge tillage had greater loss of dissolved P and NH4+-N in surface runoff (snowmelt runoff plus rainfall runoff) than the moldboard plow. This was due to leaching of nutrients from crop residue and manure. There was no effect of tillage on sediment, and total P losses in surface runoff or on mineral N losses in combined flow. Manure application had no influence on combined flow or on losses of sediment, total P, dissolved P, and NH4+-N in surface runoff. Decreased NO3--N losses occurred, however, i combined flow from the manure compared to urea treatment. This decrease was due to slow N release from manure into the soil. Total P, NH4+-N, and NO3-- N losses in snowmelt runoff were negligible compared to rainfall runoff. Dissolved P in snowmelt runoff from the manure and the ridge till treatments were greater than or equal to the dissolved P losses in rainfall runoff. Subsurface flow contributed as much flow as rainfall runoff, however, NO3--N losses through tile lines were more than through surface inlets. We concluded that rainfall runoff through surface inlets was mainly responsible for loading of tile lines with sediment, total P, and dissolved P. On the other hand, subsurface tile flow was mainly responsible for NO3-- N loading.