Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study Probes Sources of Mississippi River Phosphorus

09.05.2011
In their eagerness to cut nitrogen and phosphorus pollution in the Mississippi River and Gulf of Mexico, people have often sought simple explanations for the problem: too many large animal operations, for instance, or farmers who apply too much fertilizer, which then flows into waterways.

But according to new modeling research that examined phosphorus loading from all 1768 counties in the Mississippi River Basin (MRB), the true causes aren’t nearly so straightforward. Livestock manure is widespread in many MRB counties, for example, but it shows little relationship to water quality, say researchers at the University of Illinois at Urbana-Champaign and Cornell University in the May-June 2011 issue of the Journal of Environmental Quality.

Moreover, areas that load the most phosphorus into the Mississippi are also places where farmers add less phosphorus to the soil than they remove each year in crop harvests, suggesting that overzealous fertilizer use is not the issue.

“If it were that, it would be easy to solve. But it’s not that,” says Mark David, a University of Illinois biogeochemist who led the research. “It’s much more complex. So I think in that sense addressing the problem is harder.”

Soil erosion and tile drainage contribute large amounts of phosphorus to the Mississippi and Gulf of Mexico each year, helping fuel a “dead zone” of oxygen-starved water in the Gulf that reached near-record size last summer. Local water quality may also decline due to phosphorus-driven algal blooms.

In an effort to pinpoint the most important sources of phosphorus across the entire MRB, David’s team calculated the yearly phosphorus inputs and outputs for every county in the basin from 1997 to 2006. After aggregating these and other data within 113 watersheds throughout the MRB, they then estimated the river load of phosphorus from every county between January and June for the same time period.

Not surprisingly, counties with intensive row crop agriculture, such as those in the Upper Midwest Corn Belt states of Iowa, Illinois and Ohio, contributed the most phosphorus to rivers. However, these same counties often showed negative phosphorus balances, meaning that phosphorus outputs in crops exceeded inputs by farmers.

In other words, farmers in these regions are actually mining stored phosphorus from the soil, rather than putting more into the system, David says. “But that negative balance doesn’t have much to do with the phosphorus that gets in the river.” Instead, the overall intensity of agriculture seems to matter most. “When I’m sitting here in Illinois in a watershed that’s 95% corn and soybeans, it’s going to lose some phosphorus,” he says, “whether the balance is negative or positive.”

In addition, although animal manure is considered a major phosphorus source to streams and rivers, it was relatively unimportant to phosphorus loading across the entire MRB. David suspects the reason is that most large-scale animal farms have moved to western states in the basin, such as Colorado, where there’s less precipitation to carry manure nutrients into the Mississippi.

Phosphorus from human waste did prove significant. Counties encompassing Chicago and other major metropolitan areas “showed up as hot spots,” David says, because most municipalities don’t remove phosphorus from the otherwise clean sewage effluent they discharge into streams. The team further found that about half of the variation in phosphorus loadings was not explained by their models, suggesting that other factors also contribute, such as stream bank erosion and phosphorus deposits in river sediments.

Overall, the findings suggest that reducing phosphorus pollution will require broad adoption of practices that limit nutrient runoff, such as cover crops, buffer strips, and incorporation of fertilizers. It will also require limits on phosphorus discharge from cities.

Achieving these objectives across the entire MRB won’t be easy, but David hopes the study helps people move beyond common assumptions about causes to focus on the real issues.

“To me the value of the study is that it helps shift the debate,” David says. “The problem is not as simple as two things. It’s not as simple as too much fertilizer or manure.”

The research was funded by the National Science Foundation’s Biocomplexity in the Environment/Coupled Natural-Human Cycles Program.

The full article is available for no charge for 30 days following the date of this summary. View the abstract at https://www.agronomy.org/publications/jeq/abstracts/40/3/931.

The Journal of Environmental Quality is a peer-reviewed, international journal of environmental quality in natural and agricultural ecosystems published six times a year by the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Soil Science Society of America (SSSA). The Journal of Environmental Quality covers various aspects of anthropogenic impacts on the environment, including terrestrial, atmospheric, and aquatic systems.

The American Society of Agronomy (ASA) www.agronomy.org, is a scientific society helping its 8,000+ members advance the disciplines and practices of agronomy by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.

Sara Uttech | Newswise Science News
Further information:
http://www.agronomy.org

More articles from Agricultural and Forestry Science:

nachricht Trees and climate change: Faster growth, lighter wood
14.08.2018 | Technische Universität München

nachricht Animals and fungi enhance the performance of forests
01.08.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>