Sources and Transport of Total Nitrogen from Major River Basins of the South-Central United States, 2002

Author(s): Rebich, R.

A spatially-referenced regression on watershed attributes (SPARROW) model was developed for a 2002 base year for streams in the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River basins to describe total nitrogen loadings to the northwestern Gulf of Mexico. Ultimately, model results may be used to help develop water management plans to reduce, control, and mitigate nutrient inputs throughout the study area. Total nitrogen loads and yields generally were highest near streams in the eastern part of the study area in the Lower Mississippi basin and along reaches near the Texas and Louisiana shoreline. The highest individual source of nitrogen for the study area was from wet deposition of total inorganic nitrogen, which accounted for 36 percent on average of total nitrogen in streams from the study area. Land application of manure from confined feedlots and manure generated in pastures accounted for 22 percent, nitrogen fixation from fertilizer applications accounted for 17 percent, and nitrogen from commercial fertilizers accounted for 12 percent on average of total nitrogen in streams from the study area, which combined totaled 51 percent from agricultural and pasture land uses. Urban sources of nitrogen totaled about 13 percent on average of total nitrogen in streams from the study area, of which urban nonpoint runoff accounted for 9 percent and municipal and industrial point sources about 4 percent.

For the Yazoo River basin in northwestern Mississippi, preliminary estimates of total nitrogen load and yield were about 21,300 metric tons and about 0.64 metric tons per square kilometer, respectively, both of which agree with literature estimates for the sampling station located near the mouth of the Yazoo River prior to release into the Mississippi River. The total nitrogen load from the Yazoo represents about 2.2% of the total nitrogen load of the Mississippi River near its mouth. Nitrogen from atmospheric deposition accounted for about 25 percent of the total load leaving the Yazoo River basin. Agricultural sources accounted for about 67 percent of the total load: 31 percent by commercial fertilizers, 30 percent by nitrogen fixation from fertilizer applications, 5 percent from pastures, and 1 percent from land application of manure from confined feedlots. Urban sources of nitrogen accounted for the remaining 9 percent of the total load from the Yazoo River, of which about 5 percent came from municipal and industrial point sources and 4 percent came from urban nonpoint runoff.


Technical Presentations

  • Delta Water Quality
  • Delta Water and Agriculture
  • Wetlands
  • Water Quality
  • Sediments
  • Non-Point
  • Management and Sustainability
  • Wood Treatment
  • Modeling
  • Soil and Water Treatment


Responsible Site Design: Implementing Innovative Stormwater Management Strategies

The primary goal of the workshop is to create a dynamic learning experience that examines the role of stormwater management in the built environment. The workshop will focus on integrating ecologically sound water management approaches into site design. After the workshop, attendees will be familiar with the following concepts and technical issues:

  • Knowledge of the stormwater treatment chain
  • Knowledge of the impact of land use codes on stormwater management
  • Application of a design process that mitigates the effects of stormwater on-site
  • Knowledge of the relationship between land use codes and design for innovative stormwater management


For information contact:
Jessie Schmidt
Box 9680
Mississippi State, MS 39762