Manhattan, Kansas
May 15, 2008
Plant analysis is an excellent
"quality control" tool for wheat growers interested in high
yield wheat management, and one that most growers can take
advantage of yet this year, according to a
Kansas State University
agronomist.
The best way to use this tool depends on what the grower wants
to accomplish, said K-State Research and Extension soil
fertility specialist Dave Mengel.
"There are two primary goals of plant analysis," Mengel said.
"It can be used as a monitoring tool to ensure nutrient levels
are adequate, or as a diagnostic tool to help explain some of
the variability in
wheat growth that often occurs this time of year."
The successful use of plant analysis to meet either of these
goals starts with using proper sampling techniques.
"For monitoring purposes, 40 to 50 flag leaves should be
collected at random at the late boot to initial heading stage of
growth. Once the plant pollinates and kernel development begins,
nutrients start to flow from the stem and leaves to the
developing grain," Mengel said.
"For this reason, sampling flag leaves for nutrient monitoring
purposes is not recommended once the plant begins to shed
pollen."
The leaves should be allowed to wilt overnight to remove excess
moisture, placed in a paper bag or mailing envelope, and shipped
to a lab for analysis. Do not place the leaves in a plastic bag
or other tightly sealed container, as they will begin to
decompose during transport, and the sample won't be usable, he
said.
"Also, growers should be aware that sampling for monitoring
purposes when the crop is under stress can give misleading
results, and is not advisable," the agronomist added.
The data returned from the lab will be reported as the
concentration of nutrient elements, including potentially toxic
elements, in the plants. Most labs compare plant nutrient
concentrations to published sufficiency ranges.
"A sufficiency range is simply the range of concentrations
normally found in healthy, productive plants during surveys,"
Mengel said. "It can be thought of as the range of values
optimum for plant growth.
The medical profession uses a similar range of normal values to
evaluate blood work."
Plant analysis is also an excellent diagnostic tool to help
understand some of the variation seen in the field.
"When using plant analysis to diagnose field problems, producers
should take comparison samples from both good or normal areas of
the field, and problem spots. Collecting soil samples from the
same good and bad areas is also a good idea," he said.
Mengel said growers should not wait until the boot stage to take
diagnostic samples: "Early in the season (prior to stem
elongation), growers should collect whole plants from 20 to 30
different places in their sampling area. Later in the season,
producers should take the uppermost, fully developed leaves --
those with leaf collars visible.
Handle the samples the same as those for monitoring."
"Plant analysis is an excellent tool to monitor the
effectiveness of your fertilizer and lime program, and a very
effective diagnostic tool. Producers should consider adding this
to their toolbox," the agronomist said.
K-State Research and Extension is a short name for the Kansas
State University Agricultural Experiment Station and Cooperative
Extension Service, a program designed to generate and distribute
useful knowledge for the well-being of Kansans. Supported by
county, state, federal and private funds, the program has county
Extension offices, experiment fields, area Extension offices and
regional research centers statewide. Its headquarters is on the
K-State campus, Manhattan. |
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