Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2008
Publication Date: 11/3/2008
Citation: Smith, D.R., Livingston, S.J., Zuercher, B.W., Larose, M., Heathman, G.C., Huang, C. 2008. Nutrient losses from row crop agriculture in Indiana. Journal of Soil and Water Conservation. 63:396-409.
Interpretive Summary: Agricultural nutrient losses are contributing to hypoxia in the Gulf of Mexico and eutrophication in the Great Lakes. We monitored five drainage ditch sites, ranging from 736 to 10,600 ac, within the Cedar Creek sub-watershed of the St. Joseph River basin. Row crop agriculture, primarily corn and soybean, is the dominant land use (>70%). Among monitoring sites NO3-N loads ranged from 1.4 to 14 lb ac-1 in 2004 and from 0.04 to 6.3 lb ac-1 in 2005. Precipitation and runoff were also greater in 2004 than 2005. The greatest NH4-N, NO3-N, soluble P and total P loads were observed from the same watersheds each year, indicating precipitation, runoff, and land use are the predominant factors controlling nutrient loads. These data will assist land managers and policy makers in developing strategies to better manage our natural resources and protect water quality.
Technical Abstract: Nutrient losses from agriculture in the Midwestern United States have been identified as contributing to water quality problems such as hypoxia in the Gulf of Mexico, and eutrophication in the great lakes. Fields and catchments in the Cedar Creek sub-watershed of the St. Joseph River basin were monitored to assess the implications of agro-ecosystems on water quality. More than 70% of the land in these catchments was in row crop agriculture, primarily corn and soybeans. Most fields in this region are tile drained and the drainage water is conveyed to managed ditches. When evaluating 5 drainage ditch sites ranging from 298 to 4,300 ha (736 to 10,600 ac), there was a tremendous range in nutrient loads. In 2004, NO3-N loads ranged from 1.6 to 16 kg ha-1 (1.4 to 14 lb ac-1), whereas NO3-N loads in 2005 ranged from 0.05 to 7.1 kg ha-1 (0.04 to 6.3 lb ac-1). Precipitation and runoff were greater in 2004 than 2005. The greatest NH4-N, NO3-N, soluble P and total P loads were observed from the same watersheds for 2004 and 2005. This indicates that aside from precipitation and runoff, land use and management is likely the predominant factor controlling nutrient loads. As part of the Conservation Effects Assessment Project in Indiana, these data will assist land managers and policy makers in developing strategies to better manage our natural resources to protect water quality.