sealPurdue Science Briefs

April 1998

Purdue research helps keep phosphorus
out of surface water

WEST LAFAYETTE, Ind. -- Purdue University research is helping farmers choreograph a balancing act with phosphorus, giving plants and livestock just enough of the nutrient so they grow properly, but no more.

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U.S. researchers knew years ago that excess phosphorus in rivers could cause trouble, but they thought most of it came from urban and industrial waste, not farm fields. "Even 10 years ago the prevailing thought was that phosphorus in fields didn't move, unless it eroded away with soil," says Purdue agronomist Brad Joern.

In 1992, Joern started measuring phosphorus levels in fields and found that phosphorus can move down through soils. "Fields with a long history of phosphorus loading from manure or other fertilizer sources can lose phosphorus in surface water runoff and potentially even through tile drains three feet down," Joern says. From there it can be a quick trip to a neighboring river or lake.

Joern and colleagues from Michigan and Ohio are developing a set of new environmental guidelines that should keep phosphorus out of surface water while still giving good crop yields. The guidelines will tell producers how much manure they can spread on land without over-applying phosphorus.

The guidelines will help, Joern says, but as they start to measure phosphorus in manure, some livestock operations will find that they produce more manure than they can spread on their land.

"When manure is applied to meet the nitrogen needs of the crop, it exceeds the phosphorus requirements for the plants," says Purdue animal scientist Alan Sutton. "Repeated applications of manure on the same fields can result in a significant buildup of soil phosphorus, which might increase the potential for surface water contamination."

Purdue researchers are looking for alternatives. For example, they tried to reduce the phosphorus content of manure by changing animals' diets. Because Indiana producers are high on raising hogs, that's where they've turned their attention.

Sixty percent to 80 percent of the phosphorus in most grain fed to hogs is in a form that passes right through animals, never getting picked up and used by their bodies.

Joern and animal scientist Layi Adeola are testing a new type of corn that is naturally higher in easy-to-absorb forms of phosphorus and low in hard-to-absorb phosphorus. Such corn could reduce phosphorus levels in manure and decrease the need for supplemental phosphorus in animal diets. Joern says the preliminary results look promising.

In separate but related research, Sutton and Adeola fed pigs a diet containing the phytase enzyme, which makes hard-to-absorb phosphorus in grain easier for pigs to absorb. In their tests, pigs fed the phytase enzyme and a low-phosphorus diet gained weight and grew just as well as pigs on a normal-phosphorus diet. Pigs could better use the phosphorus in the grain, so less passed into the manure. Manure from the pigs that ate the phytase enzyme held a balance of nutrients that more nearly matched crop needs, a balance less likely to leach phosphorus into water.

Overall, Joern says, the phytase enzyme and the new, high-available phosphorus corn look like good bets for farmers who have lots of manure to spread and little land to put it on.

CONTACTS: Joern, (765) 494-9767; e-mail,
Sutton, (765) 494-8012; e-mail,

National research project focuses
on nuclear reactors

WEST LAFAYETTE, Ind. -- Purdue University researchers are leading a national effort to ensure the safety and efficiency of the next generation of nuclear power plants.

The U.S. Nuclear Regulatory Commission has established the Institute of Thermal-Hydraulics at Purdue's School of Nuclear Engineering. With a five-year, $10 million task order contract from the commission, a team of researchers from Purdue and several other universities will provide technical expertise and perform thermal-hydraulics and reactor safety research for the commission. The initial phase of this contract runs through 2002.

The institute will focus on developing base technology for new, sophisticated computer programs to accurately simulate the processes that would take place in a new, advanced type nuclear reactor. The simulations will model the behavior of the reactor under all conceivable conditions of operation, including accidents. One of the goals of the research is to produce a new graphical user interface for the computer programs, which will allow designers, regulators and other researchers to more easily use the simulations.

Before allowing construction of a new type of reactor in the United States, the Nuclear Regulatory Commission requires that its technology, design, operation, safety systems and performance be thoroughly investigated.

"The team that has been assembled to carry out this research is unarguably the most talented group of experts in this field in the world," says Mamoru Ishii, director of the institute and a professor of nuclear engineering at Purdue. "Our faculty at Purdue, who are internationally recognized for their expertise in thermal-hydraulics, are well prepared not only to lead the team effort but to make contributions to the research efforts as well."

The study of thermal-hydraulics involves investigating how fluids transfer heat in a complex system, such as a nuclear power plant. In a nuclear power plant, as in a coal-burning plant, high-pressure steam turns the blades of a turbine, powering a generator that creates electricity. In a nuclear reactor, the heat needed to boil the water to produce the steam is made by splitting certain atoms of uranium in a process called fission.

In a reactor, water is not only heated to produce steam, it also is used to cool the reactor. In addition, water and steam often flow through the reactor system simultaneously, a process called multiphase flow. Ishii said all of these elements and complex interactions in the advanced reactor will be thoroughly studied and then brought together in the computer simulations.

In addition to Purdue, the institute also includes researchers from Penn State University, the University of California, Oregon State University, University of Wisconsin, the University of Colorado and SCIENTECH Inc., a small business with international expertise in thermal-hydraulics research.

CONTACT: Ishii, (765) 494-4587; e-mail,

Professor plots course for sun-studying spacecraft

WEST LAFAYETTE, Ind. -- A Purdue University professor and two of her doctoral students have designed the trajectory for an upcoming space mission, which may shed light on the composition of the sun.

Kathleen Howell, professor of aeronautical and astronautical engineering at Purdue, in collaboration with her students and Jet Propulsion Laboratory colleague Martin Lo, designed the trajectory for the spacecraft that will carry out the Genesis Mission, scheduled for launch in 2001 by the National Aeronautics and Space Administration. The primary goal of the mission is to collect solar wind particles -- material being swept out of the sun -- and return them to Earth for analysis.

The Genesis Mission is the newest addition to NASA's Discovery Class Program, which is charged with building lower-cost, highly focused scientific spacecraft.

The solar wind particles collected will include samples of isotopes of oxygen, nitrogen, the noble gases and other elements. The spacecraft will return the samples to Earth in 2003.

"This information can be used to validate theories concerning the composition of several objects in the solar system, including the sun and planetary atmospheres," Howell says. "To successfully collect these particles, the spacecraft must be beyond the magnetosphere of Earth. However, to keep the mission operation costs low, the spacecraft needs to remain as close to Earth as possible."

The trajectory Howell designed with her students, Brian Barden of West Lafayette and Roby Wilson of Vincennes, Ind., will put the spacecraft in "orbit" near a libration point in the sun-Earth system, nearly a million miles from Earth in the direction of the sun. A libration point, or Lagrange point, is where the gravitational pull from two or more heavenly bodies, plus the centrifugal force from their rotation, cancel each other out.

"These orbits are very complicated, much more complex than the orbit of a planet around the sun, which is why we often refer to the orbit as 'near' a libration point instead of 'around' a libration point," Howell says.

Howell, who has 15 years of experience in trajectory design for libration point missions, says a spacecraft in orbit near a libration point offers a stable venue for making observations and taking data. "Satellites in this region help us better understand the environment around the sun and Earth," she says. "A trajectory about one of these points is the ideal platform for this mission."

The spacecraft will gather solar particles for about two years before it returns to Earth, where it will be retrieved from the air over the Utah desert.

CONTACT: Howell, (765) 494-5786; e-mail,

Compiled by Amanda Siegfried, (765) 494-4709; e-mail,
Purdue News Service: (765) 494-2096; e-mail,

Purdue agronomist Brad Joern catches a sample of water from a farm drainage tile. Joern found that phosphorus can move into drain-tile water from fields that have a long history of phosphorus loading. A decade ago, scientists believed that phosphorus in fields didn't move, unless it eroded away with soil. (Agricultural Communication Service Photo by Mike Kerper)
Color photo, electronic transmission, and Web and ftp download available. Photo ID: Joern.Phosphorus
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