top 10 lessons learned in 6 years of on-farm sensor demos peter scharf university of missouri > ?
TRANSCRIPT
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Top 10 lessons learned
in 6 years of on-farm sensor demosPeter Scharf
University of Missouri
> ?
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123 fields123 fields
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#11: Works with any kind of equipment
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Crop sensors can be used for Crop sensors can be used for sidedressing anhydrous…sidedressing anhydrous…
sensorssensors
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…or sidedressing solution
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…or with a high-clearance spinner
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…with a big sprayer
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…or a big injector
#10.5: Farmers like toys#10.5: Farmers like toys
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…With Raven, Raven Viper, Rawson, Falcon, or MidTech controllers (thanks, Scott!)
…but not AgLeader InSight, Deere, New Leader: no serial input!
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#10: Lots of preparation goes into a successful demo
(or adoption)
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Preparation
• Recruit cooperators• Build brackets to hold sensors
on the applicator• Controller: port?!,
communication parameters, programming
• Coordinate plan for preplant N• Apply high-N reference area• Plan for yield documentation
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#9: It’s important to filter out readings from bare soil
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Filtering soil
• Not as easy as it sounds• Different ‘reflectance’ for:
– Different soils– Same soil with different moisture levels– Same soil with different residue levels
• If you don’t, you’ll put high N rates on thin (or nonexistent) stands
• Angled sensors may also solve this problem
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0
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4287195 4287200 4287205 4287210 4287215
northing
Crop
Circ
le 2
10 y
ello
w/N
IRRandom 20 m of sensor data
V7, 2009
High-NHigh-Nreference valuereference value
N rate = 220N rate = 220
Average N rate with all data = 248
Bare soil cutoff?Bare soil cutoff?Average N rate with cutoff = 161
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Bare soil cutoff value
• When we do a demo, measuring bare soil is the first thing we do when we pull into a field
• Then we set a cutoff value to discard any data at or near this value
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#8: We can combine sensors with other information sources to make
N rate decisions
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We’ve combined sensors real-time with:
• Yield zone maps– Add to sensor-based N rate in high-yield zones– Don’t modify in medium-yield zones– Subtract from sensor-based N rate in low-yield
zones
• Future N via lagoon effluent through pivot– Calculate sensor N rate, subtract lagoon N
from rate
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Productivity Zones and Treatment LayoutYield zone example
Low: subtract 25Medium: don’t changeHigh: add 12
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#7: Varying rates of liquid N (anhydrous or UAN solution) is hard
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Varying flow rates is difficult
• Double flow requires 4x pressure
• Highest rate = highest pressure (100 psi?)
• What happens as you drop pressure?– Distribution along bar or boom becomes
uneven– Starts at about ¼ max (25 psi?)– N rate = ½ max
• If top rate = 150, bottom rate = 75
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Is this good enough?
• Yes, but it would be better to have a wider range
• New nozzle bodies with spring-loaded orifice– Orifice gets bigger as pressure increases– Available from Greenleaf, SprayTarget– Gives wide rates, even spread, and doesn’t
pop hoses
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#6: A good reference value is crucial
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What about Virtual Reference Areas?
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Virtual reference exampleHigh-N reference area
Average N rate = 96
Best 5% from strip with 75 lb Pre-plant
Average N rate = 73
Best 3 sec from strip with 75 lb Pre-plant
Average N rate = 43Producer N rate = 60
This N rate out-yielded producer rate by 18 bushels
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#5: Sensor values drift
(Nitrogen need doesn’t)
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Sensor values drift during the day
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Sensor values drift during the day:Vis/NIR
6AM 8PM
8 days of measurements
Same plant all day long
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Error in N rate due to drift:Crop Circle Vis/NIR
6AM 8PM
0
50
100
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Error in N rate due to drift:Greenseeker Vis/NIR
6AM 8PM0
50
100
150
200
250
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Greenseeker error in N rate reduced using NDVI equation
6AM 8PM0
50
100
150
200
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Greenseeker error in N rate reduced even more using
correction equation
6AM 8PM0
50
100
150
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Why do sensor values drift during the day?
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Water effects on sensorsWater effects on sensors
Strips with producer N rate
PM
Next AM--dew
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Water changes sensor values
0.7
0.75
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0.9
ND
VI
Greenseeker Crop Circlewatering
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My recommendation:To avoid bad N rate
decisions, re-measure high-N reference area at
least every 2 hours (especially with Greenseeker)
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Crosswise high-N reference strips: Crosswise high-N reference strips: a slick way to update high-N valuea slick way to update high-N value
High-N High-N reference reference stripsstrips
Program system to Program system to update reference update reference value every time value every time you drive across you drive across them (Scott!)them (Scott!)
With a plane, With a plane, you could do a you could do a lot of these in a lot of these in a hurryhurry
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#4: Watching the sensors work sells them
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#3: Sensors can’t do everything
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What can’t they do?
• Sensors can’t distinguish between low N need and zero N need
• ‘Top up’ is the wrong idea
• Sensors can distinguish between low, medium, and high N need
• Give them room to work by applying low or zero N preplant
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#2: Timing is the biggest issue to producers, retailers, advisors
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N sensor meeting, March 2009
• Producers, retailers, consultants, agencies, researchers, extension folks
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Topics we could discussTopics we could discuss
6%
7%
3%
8%
7%
10%
38%
21% 1. Obstacles to success2. Timing risks and benefits3. Need for preplant N4. Sensor availability, pricing, issues5. How many sensors are needed?6. Producer vs. retailer applicators7. Features you’d like to see8. Corn vs. wheat (vs. cotton)
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Obstacles to successObstacles to success
9%8%2%8%7%22%20%13%11% 1) Need for high-N reference area
2) Cost of application equipment3) Risk of not getting done at planned time4) Good equations to predict N rate5) Sensor cost6) Limited range of liquid rates7) Sensor values drift during the day (return to ref area?)
8) Conflicts with other field activities9) Emergence skips = soil interference
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Timing risks and benefits
• Want to go early!
• Sensors: 7-10 days later than normal sidedress– True for corn, cotton, wheat– Even people who always sidedress balk– Why?– Farmers like to get things done!
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Timing risks and benefits
• Risk:– Don’t get done with planned equipment
(tractor, for example)
• Solution:– Limit acres using sensors
• Most variable land• Or land with biggest chance of reducing N rate
– OR Have plan B for those years when you don’t get finished using planned equipment
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Corn N timing: Full yield can be Corn N timing: Full yield can be achieved even with late applicationsachieved even with late applications
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growth stage of single or main N applic.
yiel
d r
elat
ive
to p
rep
lan
t N
missouri
nebraska
oklahoma
minnesota
iowa1’ 2’ 4’ 7’
tassel
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Yield response to N depends a lot Yield response to N depends a lot on need, not much on timingon need, not much on timing
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time of 200 lb N application
yie
ld r
es
po
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e t
o N
(b
u/a
c)
plant 18” 36” 80”
Eight production corn fields, 19978 small-plot trials in producer fields, 1997
Field with low need for N
Field with high need for N
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Timing risks and benefits
• Benefit:– Low risk of N loss before crop uptake
• How much of a benefit is this?– It depends on the weather—big benefit when wet– I estimate an average yield hit of 20 bu/acre this year
between here and Missouri (windshield survey)
• Big benefit last two years in Missouri• Widely used in southeastern U.S.
– More rainfall than midwest
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180 N at 180 N at planting: LOST!!planting: LOST!!
110 N at knee high:110 N at knee high:DELIVERED!DELIVERED!
Sidedress N kicks butt in 2008Sidedress N kicks butt in 2008(and 2009)(and 2009)
+38 bushels+38 bushels
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Wheat: topdress N timingWheat: topdress N timing
0
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N timing
wh
eat
yiel
d
Jan
Feb
March
Columbia 2005
April: probably too late
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#1: We can make money managing N with sensors
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Making money with sensors
• Compared to what?
• Compared to current producer practice
• Head-to-head comparisons– At least 3 sensor, 3 producer rate strips/field– Total 55 fields 2004-2008
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ProducerProducerRate = 100Rate = 100
Sensor RateSensor RateAve. = 73Ave. = 73
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August 1 Aerial Photo after the June 13 UAN Application
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215.4 212.1 204.2 212.4 215.5 204.9 206.6
214.1 208.0 208.5 206.6 206.6 211.6 205.4
Variable
Fixed
Avg Bu/A
208.6
210.2
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Making money with sensors
• 55 side-by-side comparisons
• Sensor outcomes:– 2 bu/acre yield increase– 14 lb N/acre saved– $13/acre at this year’s prices– $19/acre at last year’s prices
• Making money with sensors is easier when prices are high
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Making money with sensors
• Different in different years
• 2004-2007– No effect on yield– Saved 24 lb N/acre
• 2008 (very wet year)– Used 15 lb extra N/acre– Made 8 extra bushels
– Adjusted for wet weather and N loss!
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Making money with sensors
• Even easier with program support• Missouri NRCS: EQIP-approved practice since
2006– 2006: $60/acre ($20/acre x 3 years)– 2007: $38/acre ($19/acre x 2 years)– 2008: $73/acre ($36.50/acre x 2 years)
• But not easy for grain farmers to get EQIP conracts
• Rumor: substantial 2010 EQIP money for nitrogen management
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Making money with sensors
• We’re making money:– At any growth stage from V6 to V16
– Whether we lower or raise N rate relative to the producer’s rate
– At any yield level
– At any preplant N rate
• We’re losing money when the reference area is bad
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An advertisement to end:Nitrogen Watch feature on my
website
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Areas shown in cross-hatch are ‘danger areas’
Nitrogen watch for well- and moderately well-drained soils