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Published byRalph Eaton Modified over 9 years ago
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Top 10 lessons learned in 6 years of on-farm sensor demos Peter Scharf University of Missouri > ?
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123 fields
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#11: Works with any kind of equipment
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Crop sensors can be used for sidedressing anhydrous… sensors
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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
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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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Random 20 m of sensor data V7, 2009 High-N reference value N rate = 220 Average N rate with all data = 248 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 Layout Yield zone example Low: subtract 25 Medium: don’t change High: 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 example High-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 = 43 Producer 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 Greenseeker: systematically through the day All sensors: ‘randomly’ (not understood) All sensors: with leaf wetting and drying
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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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Sensors moving (½-mile strip average) Greenseeker
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Error in N rate due to drift: Crop Circle Vis/NIR 6AM8PM 0 50 100
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Error in N rate due to drift: Greenseeker Vis/NIR 6AM8PM 0 50 100 150 200 250 300
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Greenseeker error in N rate reduced using NDVI equation 6AM8PM 0 50 100 150 200
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Greenseeker error in N rate reduced even more using correction equation 6AM8PM 0 50 100 150
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Why do sensor values drift during the day?
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Water effects on sensors Strips with producer N rate PM Next AM--dew
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Water changes sensor values watering
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Both sensors change when a cloud covers the sun cloud
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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: a slick way to update high-N value High-N reference strips Program system to update reference value every time you drive across them (Scott!) With a plane, you could do a lot of these in a hurry
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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 discuss 1.Obstacles to success 2.Timing risks and benefits 3.Need for preplant N 4.Sensor availability, pricing, issues 5.How many sensors are needed? 6.Producer vs. retailer applicators 7.Features you’d like to see 8.Corn vs. wheat (vs. cotton)
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Obstacles to success 1)Need for high-N reference area 2)Cost of application equipment 3)Risk of not getting done at planned time 4)Good equations to predict N rate 5)Sensor cost 6)Limited range of liquid rates 7)Sensor values drift during the day (return to ref area?) 8)Conflicts with other field activities 9)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 achieved even with late applications 1’2’4’7’ tassel
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Yield response to N depends a lot on need, not much on timing plant18”36”80” Eight production corn fields, 1997 8 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 planting: LOST!! 110 N at knee high: DELIVERED! Sidedress N kicks butt in 2008 (and 2009) +38 bushels
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Wheat: topdress N timing 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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Producer Rate = 100 Sensor Rate Ave. = 73
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August 1 Aerial Photo after the June 13 UAN Application
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215.4212.1204.2212.4215.5204.9206.6 214.1208.0208.5206.6 211.6205.4 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
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