ARS | Publication request: Factors Influencing Nutrient Losses from Agriculture in the St. Joseph River Watershed, Northeast Indiana

Submitted to: Water Resources Association
Publication Type: Abstract Only
Publication Acceptance Date: March 21, 2008
Publication Date: May 14, 2008
Citation: Smith, D.R., Livingston, S.J., Heathman, G.C., Huang, C. 2008. Factors Influencing Nutrient Losses from Agriculture in the St. Joseph River Watershed, Northeast Indiana [abstract]. In: Abstracts Water Resources Association 2008 Meeting. May 14-16, 2008, Bloomington, Indiana. 2008 CDROM.

Technical Abstract: Nutrient losses from agricultural watersheds in Indiana have been implicated in the hypoxic zone in the Gulf of Mexico as well as massive algal blooms in Lake Erie. We monitored water quality from fields and drainage ditches in the St. Joseph River Watershed, Northeast Indiana. The complex ‘pot-hole’ topography and associated hydrology have a tremendous impact on nutrient losses from these watersheds, as the relative amount of land in ‘pot-holes’ significantly affected TKN and soluble P loads. Land use is also an important factor in nutrient transport from watersheds, as the proportion of land in corn significantly affected NH4-N, NO3-N, and TKN loads. Management of drainage ditches is also an important factor influencing nutrient losses. During our monitoring period, one of the ditches was dredged. The immediate impact of dredging was shown to be an increase in the N and P transport in the water column. The longer-term (up to one year) impacts were quite different, as this ditch resulted in a net loss of 12 kg of soluble P and 5 kg of TP (i.e. greater mass loss of P upstream of dredging than downstream of dredging) during the monitored year after dredging occurred.