Influence of Alternative and Conventional Farming Practices on Subsurface Drainage and Water Quality

Influence of Alternative and Conventional Farming Practices on Subsurface Drainage and Water Quality

2007

Agricultural runoff contributes nutrients to nonpoint-source pollution of surface waters. This study was conducted to investigate the potential use of alternative farming practices to improve water quality. The study examined the effects of both alternative and conventional farming practices on subsurface drainage and nitrogen and phosphorus loss through subsurface drainage from glacial till soils (i.e., Calciaquolls, Endoaquolls, Eutrudepts, Hapludolls) in southwest Minnesota. Alternative farming practices included organic management practices, species biodiversity, and/or practices that include reduced inputs of synthetic fertilizer and pesticides. Conventional farming practices include corn–soybean (Zea mays L.–Glycine max L., respectively) rotations and their associated recommended fertilizer rates as well as pesticide usage. Precipitation was highly variable during the 3-yr study period including a below-average year (2003), an average year (2002), and an above-average year (2004). Results indicate that alternative farming practices reduced subsurface drainage discharge by 41% compared with conventional practices. Flow-weighted mean nitrate-nitrogen (nitrate N) concentrations during tile flow were 8.2 and 17.2 mg L?1 under alternative and conventional farming practices, respectively. Alternative farming practices reduced nitrate N losses by between 59 and 62% in 2002 and 2004 compared with conventional practices. Ammonium-nitrogen (ammonium N), orthophosphorus, and total phosphorus losses in subsurface drainage were very low and did not pose a substantial risk of pollution. Results suggest that alternative farming practices have the potential to reduce agricultural impacts on water quality.

Oquist, K. A.
Strock, Jeffrey S.
Mulla, David J.

Associate Professor and Soil Scientist, U of M - SWROC
U of M, Dept. of Soil, Water and Climate

Water Conveyance & Hydraulics
Water Economics

nitrogen
nitrogens
non-point source
non-point sources
nonpoint source
nonpoint sources
non point source
non point sources
surface water
surface waters
surface-water
surface-waters
surfacewater
surfacewaters
fertilizer
fertilizers
fertiliser
agricultural runoff
agricultural runoffs
agricultural run-off
agricultural run off
ag runoff
ag run-off
ag run off
nonpoint source pollution
non point source pollution
non-point source pollution
phosphorus
phosphorous

2000-2009

Yes

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