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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #313740
Title: 4R Water quality impacts: An assessment and synthesis of forty years of drainage nitrogen losses

Author
item CHRISTIANSON, LAURA - Freshwater Institute
item Harmel, Daren

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2015
Publication Date: 11/6/2015
Publication URL: http://handle.nal.usda.gov/10113/61904
Citation: Christianson, L.E., Harmel, R.D. 2015. 4R Water quality impacts: An assessment and synthesis of forty years of drainage nitrogen losses. Journal of Environmental Quality. 44:1852-1860.

Interpretive Summary: The intersection of agricultural drainage and nutrient movement in the environment has led to multi-scale water quality concerns. This work reviewed and quantitatively analyzed nearly 1300 study-years of drainage nitrogen loss data to develop a more comprehensive understanding of the impacts of agricultural management practices within drained landscapes across North America. Using the new Drain Load table in the existing “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database, relationships were developed across nitrogen application rates for dissolved nitrogen drainage loads and corn yields. Corn-soybean rotations and use of organic nitrogen sources were more favorable for nitrogen loss and corn yield than continuous corn and inorganic nitrogen sources, respectively. The lack of significant differences between nitrogen application timing or application method treatments indicated neither should receive primary focus as dissolved nitrogen reduction strategies. Broad-scale analyses such as this can help identify major trends for water quality, but accurate implementation of the conservation management within the “4R” approach will require site-specific knowledge to balance agronomic and environmental goals.

Technical Abstract: The intersection of agricultural drainage and nutrient mobility in the environment has led to multi-scale water quality concerns. This work reviewed and quantitatively analyzed nearly 1300 site-years of drainage nitrogen load data to develop a more comprehensive understanding of the impacts of 4Rs nutrient management practices within drained landscapes across North America. Using the new Drain Load table in the existing “Measured Annual Nutrient loads from AGricultural Environments” (MANAGE) database, relationships were developed across N application rates for dissolved N drainage loads and corn yields. Corn-soybean rotations and use of organic N sources were more favorable for N loss and corn yield than continuous corn and inorganic N sources, respectively. The lack of significant differences between N application timing or application method treatments indicated neither should receive primary focus as dissolved N load reduction strategies (p = 0.934 and 0.916, respectively). Broad-scale analyses such as this can help identify major trends for water quality, but accurate implementation of the 4Rs approach will require site-specific knowledge to balance agronomic and environmental goals.