Fantasy Irrigation
PORTAGEVILLE, MO.
In fantasy football, wannabe
football coaches in TV-land
are able to “draft” real
football players to compile
their dream-squad football
team which they can clash on
Sundays with other dream
teams. Recently, in a similar
mode, irrigation specialists
from around the country got together on the Internet
and developed a dream list of irrigation
practices they felt would help US irrigators.
Starting off as a “Top Ten” irrigation practices
list, the list soon expanded. The irrigation
“coaches” came from AR (Chris Henry), MS (Lyle
Pringle, Joe Massey and Jason Krutz), NM (Blair
Stringham) and MO (Joe Henggeler). Here are
some of the dream irrigation practices that they
came up with.
Management
• Measure flow and the total amount of irrigation
applied by installing a flow meter.
• If a permanent meter cannot be installed,
borrow a portable flow meter, take a reading
while at the same time linking it to some hour
totalizer (e.g., on a power unit, panel control
box, etc.). Seasonal hours of operation then can
be used to obtain annual irrigation depth applied.
• Use newly collected data to give yourself an
end-of-year report card by calculating your irrigation
use efficiency (IUE). IUE is your irrigated
yield minus your dryland yield divided by total
inches of irrigation applied. Compare to published
IUE values. For example, a typical IUE
for corn is 11.9 bu/ac/inch of irrigation. If your
IUE, however, was just 10.0 bu/ac/inch than
you are 84 percent of the average – a solid “B”,
but definitely an “A”, so you might want to investigate
ways to improve you irrigation efficiency.
• Schedule irrigation with a computer-based
program that uses weather data or with an atmometer
(something like a mini pan evaporation
pan on stilts).
• Better yet, use soil moisture sensors (ideally
wireless) to schedule irrigation.
• Mistakes on irrigation often occur at the beginning
and at the end of the season.
• For example, the computer program
Arkansas Scheduler (AS), is a great tool that
times irrigation based on a set amount of water
used up in the top part of the soil profile (termed
the deficit). However, early on when the plants’
roots are still small, the deficit amount is actually
too great. Normally, the mid-South receives
some amount of rainfall around planting and
thus problems don’t occur. But when a dry spell
occurs at planting, the AS won’t call for irrigation
as the deficit as not been met. I know this
to be true, having learned it in the been-theredone-
it school.
• Don’t cut off irrigation too early. Water until
the corn milk line is at the ½ to ¾ stage and
soybeans are well into the R-6 stage, with some
foliage showing yellowing and the beans in the
pod are squared off touch each other.
• For both corn and beans obtain information
on the test weight since late-season irrigation
practices affect yield primarily by increasing
seed mass and sometimes is a reflection of how
right on the last irrigation was. Corn tests
should be > 56 lbs/bu and normal soybeans
should have a seed that when laid on a penny
will cover Mr. Lincoln’s face.
• Go to the air – aerial images of your irrigated
fields could show irrigation-related problems
(especially on pivots where they are easy to visualize
as they show up as concentric rings).
Use your yield monitor data (especially on furrow
irrigated fields) to see if you can catch some
irrigated-related problem, say weaker yields at
the bottom (rows getting out too slow) or in the
top half of the fields (possibly running water too
long).
Tips for Furrow Irrigation
• When using poly-pipe, based the sizes of the
punched holes by using computerized hole-sizing
with PHAUCET (NRCS) or Pipe Planner (Delta
Plastics). This ensures that outlet uniformity
occurs and even adjusts for varying row lengths.
• Use surge valves. Surge irrigation can improve
application efficiency up to 50 percent relative
to conventional furrow systems. The
Bootheel Irrigation Survey (BIS) showed that furrow
irrigators using surge produced $98, $78,
and $28/acre more on corn cotton and full season
soybeans that furrow irrigators not using
surge.
• Improve the points of distribution in your
field by installing additional underground pipe.
Cost share is available in some places. This
commonly cited by people who have participated
in various components of EQIP cost
share, as being the item that has helped them
the most.
• Weight the cost of reducing length of furrow
versus the benefits received with shorter runs.
Water will get to the end much quicker thus decreasing
pumping costs and improving the
down-row uniformity. Remember cost share to
help. Averaging 6 furrow advance studies on the
Internet, I found that when the furrow length is
shortened to 80, 60 and 50 percent of the original
length, the out-times are 35, 62, and 75
percent less, respectively.
• Cut back flow (running a large furrow stream
early, allowing water to advance quickly to
about ¾ of the field’s length, and then “cut
back” the engine RPM to reduce flow). Anybody
say “Murphy switch”?
• Install a tail water recovery system to increase
irrigation efficiency to capture runoff
water from the furrows and reuse it.
Tips for Sprinkler Systems
• For sprinkler systems, evaluate the sprinkler
nozzle package. Sprinkler nozzles older than 7
years should be checked annually. Nozzles can
be checked for uniformity using catch cans or
rain gauges. Some types of nozzles may wear
out faster, especially if sand is entrained in the
irrigation water source.
• Check the precipitation rate received underneath
the lateral to that received underneath
the end gun – they should be equal, but are
often not so. The remedy is easy – change the
orifice tip of end gun.
• While re-nozzling seek to reduce pressure
(the last nozzle only needs to have 7 or 8 PSI).
Pressure breaks up droplets causing increased
wind drift. An added advantage is that lowering
pressure reduces pumping costs.
• Choose nozzle types based on reducing drift.
For example, a serrated splash plate that forms
spider legs of water won’t have as much drift as
will flat splash plates. Rotator type sprinklers
(again primarily because of large drop size)
won’t drift as much as impacts.
• Use drops; the lower ultimate placement of
the nozzle, the better, especially in windy areas.
While the nozzles need to clear the top of a corn
crop, a drop to this level is better than the sprinkler
being on top of the span.
Tips for Rice Irrigation
• Improve water savings by going to zero-grade
or using multiple inlet irrigation in contour and
precision graded fields. Zero-grade uses about
2/3 of the water of levee systems and multipleinlet
reduces water use by about 25 percent for
contour and precision level system. Combine
these with the use of rice flood depth gauges to
further improve flood management, allowing for
more-efficient rainfall capture and reduced
over-pumping.
• Multiple-Inlet Rice Irrigation (factsheet):
http://msucares.com/pubs/publications/p2338.pdf
8.pdf
• Multiple-Inlet Rice Irrigation (video):
http://www.youtube.com/watch?v=XR2JNsp-MXkk-
MXkk
• Rice Flood Depth Gauge (factsheet):
http://msucares.com/pubs/infosheetsresearch/i1358.pdf
i1358.pdf
• Follow current research on decreasing number
of days with flood on the rice without hurting
yield, and see if it might work for you.
• If running open discharge with an engine to
keep a field flooded up, run at the RPM that produces
the cheapest water. Obviously, the flood
has to be maintained but do it at the RPM that
has the lowest $/acre-inch. Δ
DR. JOE HENGGELER: Irrigation Specialist
Commercial Agricultural Program, University of
Missouri Delta Center