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Nitrogen in Subsurface Discharge from Agricultural Watersheds
Author(s) -
Burwell R. E.,
Schuman G. E.,
Saxton K. E.,
Heinemann H. G.
Publication year - 1976
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1976.00472425000500030022x
Subject(s) - surface runoff , hydrology (agriculture) , environmental science , loess , watershed , subsurface flow , nonpoint source pollution , discharge , erosion , fertilizer , rill , soil water , agronomy , drainage basin , soil science , geology , groundwater , geography , ecology , paleontology , geotechnical engineering , cartography , geomorphology , machine learning , computer science , biology
The nitrogen in subsurface discharge and surface runoff was measured from four agricultural watersheds on Missouri Valley deep loess near Treynor, Iowa, from April 1969 through March 1974. The data showed that, with the agricultural management practices used on the watersheds, the subsurface discharge of water ranged from 62 to 88% of the average annual stream flow. Nitrate in subsurface discharge accounted for 84 to 95% of the total average annual soluble N discharged in stream flow. A terraced watershed continuously cropped to corn ( Zea mays L.) had reduced surface runoff, sheet‐rill erosion, and associated nitrate‐nitrogen discharges, but had increased subsurface discharge of water and soluble N as compared with two contoured corn watersheds. Nitrogen fertilizer applied at a high rate (448 kg ha −1 year −1 ) exceeding crop needs on the terraced and contoured corn watersheds, increased five‐ and threefold the average annual subsurface discharge of NO 3 ‐N, respectively, as compared with a contoured watershed fertilized with N at a normal rate (168 kg ha −1 year −1 ). To control the watershed discharge of N and subsequent pollution of stream flow from the Iowa and Missouri deep loess hills requires N fertilizer application rates that do not exceed crop needs and using conservation practices that minimize soil erosion and deep percolation.