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Agricultural Research Service scientists
investigate corn’s appetite for phosphorus
By
USDA Agricultural Research Service
May 7, 2023
DIAL IT BACK: USDA Agricultural Research Service
scientists in Indiana are working on the first steps to refining
phosphorus application recommendations for corn. Unchecked, corn
plants will take up 25% to 80% more phosphorus than they need to reach
full grain-yield potential. Continuing research will help farmers
essentially put their corn plants on a diet.
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When it comes to food, plants can “eat” more than
they need — just like the diner who can't resist another stop at the
buffet line despite already feeling full. Indeed, with respect to
phosphorus, corn plants will keep taking up the nutrient 25% to 80%
beyond what's needed to reach their full grain yield, scientists with
the USDA Agricultural Research Service in West Lafayette, Ind., have
found.
The corn plant’s gluttonous appetite for phosphorus is known as
“luxury consumption,” and in extreme cases, it can decrease grain
yields. Up until recently, though, corn’s luxury consumption had only
been demonstrated in studies with nitrogen and potassium. However, no
direct links to phosphorus had yet been established, according to Chad
Penn, a soil scientist with the ARS National Soil Erosion
Laboratory in West Lafayette.
To investigate the matter, Penn, Purdue University graduate student
Matt Wiethorn and Purdue agronomy professor James Camberato used a
state-of-the-art “grow room” and hydroponics system. This enabled the
researchers to precisely control the root environment of corn plants
and the timing of phosphorus applications to them in pots filled with
sand. More significantly, it allowed the researchers to monitor the
bioavailability of phosphorus to corn plants more easily than growing
them in field plots.
“This system demonstrated that it could produce corn that is the same
as field-grown corn, both physically and chemically,” Penn noted.
“Developing it was a huge hurdle in being able to do this research on
corn’s luxury consumption of phosphorus,” he added.
Study examines phosphorus applications
The researchers began the study in 2019, using several corn
hybrids, and published the results in the January issue of the
journal Agronomy.
Among the study’s findings: The corn hybrids needed an average of 580
milligrams of phosphorus per plant to reach their maximum grain yield.
Beyond that, “Excess phosphorus uptake caused a decrease in grain
yield, which was attributed to reduced movement [translocation] of
copper and zinc from the corn plant roots to grain,” said Penn, whose
team published a companion paper in Agronomy.
Penn noted the research is a first step toward determining whether
current phosphorus application recommendations can be refined based on
what the corn plant actually needs for optimal yield, and how much of
the nutrient is already present in the soil (the type and condition of
which can vary from one location to another). “Knowing the target
phosphorus uptake value of 580 milligrams per plant can be used in
developing more robust and precise soil phosphorus fertility
recommendations in the future," he added. More broadly, such
adjustments can contribute to natural resource sustainability, since
phosphorus fertilizers come from materials mined from finite geologic
supplies in different parts of the world.
Penn’s other research on nutrient management practices includes
co-developing the P-trap, a software application that farmers and
others can use to design, build and install in-field phosphorus
removal systems to help reduce some of the “left-over” phosphorus that
can escape the field as runoff and potentially compromise water
quality.
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