Crops
64 www.FarmProgress.com ◆ September 2013
Prairie Farmer
1-acre soil sampling
worth considering
By TOM J. BECHMAN
R
ULON Enterprises samples soils on
1-acre grids. Two family members,
Ken and Jane, were named Indiana
Master Farmers this summer. Ken’s mom
and dad, Jerry and Carol, were Indiana
Master Farmers in 1993. Ken’s cousin
Rodney is in charge of 1-acre sampling.
They believe it helps them fine-tune the
soil fertility level, and allows them to make
better decisions.
What do these Indiana Certified Crop
Advisers think? Here are their answers:
Question: One of the Master Farmer families talked about testing on 1-acre grids. I’ve
been sampling by soil type. Would switching
to 1-acre grids pay in the long run?
■ Danny Greene, Greene Ag
Consulting Inc., Franklin, Ind. It makes
the best sense to break fields into zones
for sampling by factors influencing soil
fertility. Soil type is at the top of the list.
Others include past farming practices and
topography (lay of the land).
Small sample areas of 1 acre could increase the accuracy, but may be cost-prohibitive. If you don’t have any idea of the
history of the field, small sampling areas
may help gather initial soil fertility data.
Key Points
■ Many crop consultants make the case
for 1-acre grids.
■ One-acre grids make the most sense if
you’re varying the rate of inputs.
■ Going to 1-acre grids takes more time
and money.
Then, small zones can be grouped into like
soil fertility zones.
■ Steve Dlugosz, agronomist, Harvest
Land Co-op, Richmond, Ind. The more
samples pulled in a field, the greater the
detail of soil test variability across the
field. Many times, the total number of
samples pulled when sampling by soil type
is fewer than the number pulled using 2.5acre grids.
One-acre grids take this to an even
higher level of detail. It’s the preferred
sampling method for many CCAs making
variable-rate nitrogen recommendations. Some CCAs also like 1-acre grids for
making variable-rate seed recommendations, since soil type boundaries may not
be exact.
■ Jesse Grogan, L&G Seeds agronomist, Lafayette, Ind. Yes, it would pay in
the long run if you are considering precision farming techniques and have good soil
PRESAMPLING PREPARATION: Daniel Bechman, Franklin, Ind., shows a field
map that he was marking for soil sampling. He worked for Danny Greene, Greene Ag
Consulting, at one time, pulling soil samples.
fertility. The optimum measurement level
is 1-acre grids; otherwise, 2- to 2.5-acre
grids are used. Grid-sampling is also useful
in fields receiving manure or irrigation.
Management zone sampling is also
effective and costs less, but doesn’t provide as much accuracy as grid-sampling.
Precision farming techniques include variable-rate seeding, variable-rate nutrient
management, and drainage and water management.
Soil sampling for precision agriculture
is focused on areas within fields, compared
to a whole field of soil type averages. It’s
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also important to measure changes in soil
test values according to management programs used within each field.
One-acre grids, although costing more,
allow for measuring more accurate soil
fertility levels. Soil sampling in grids can
help interpret the variability observed in
yield maps, aerial photographs and remote
sensing images.
Remember that other factors affect
variability. They include soil compaction,
slope and elevation, soil depth, and environmental stress factors such as weeds
and insects.