Crop Sensors to Control Variable-Rate N Applications: Five Years of On-Farm Demonstrations
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Crop Sensors to Control Variable-Rate N Applications: Five Years of On- Farm Demonstrations Peter Scharf, Kent Shannon, Harlan Palm, Ken Sudduth, Newell Kitchen and Scott Drummond, Univ. of Missouri and USDA-ARS Introduction • Optimal N rate often varies widely within & among fields • Weather has a large influence on optimal N rate •Static properties can’t predict • Color & reflectance of crop is strongly related to N status & need Methods •Identify producers/retailers with: • Interest • Sidedress/topdress equipment • Controller with serial input •Develop algorithm to convert sensor values to N rates •Develop control software •Make sensor brackets •Apply high-N reference area •Apply in-season N • Producer rate and sensor variable- rate side by side • Minimum 3 replications sensors sensors Computer in cab reads sensors, calculates N rate, directs controller Controller runs ball valve to change fertilizer rate Locations ofsensor dem onstration fields 2004-2009 Period # Field s Effect of sensor N management* on: Yield N rate Profit Mg ha -1 Kg N ha -1 $ ha -1 2004- 2007 41 0 -27 +30 2008 12 +0.6 +18 +72 *Effect is calculated relative to an in-season N application whose rate was chosen by the producer Lessons learned • A good high-N reference area/value is critical • Sensor values drift— need a solution • Timing is the biggest issue to producers 0 50 100 150 200 250 0.8 1 1.2 1.4 1.6 1.8 Visible/near infrared relative to high-N plots O ptim alsidedress N rate Turning a sensor reading into an N rate Cropscan, Crop Circle V6-V7 (line basd on data points shown) Crop Circle V8-V10 Greenseeker V8-V10 Greenseeker V8-V10 Greenseeker V6-V7 Greenseeker V6-V7
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Controller runs ball valve to change fertilizer rate. Computer in cab reads sensors, calculates N rate, directs controller. sensors. Crop Sensors to Control Variable-Rate N Applications: Five Years of On-Farm Demonstrations. - PowerPoint PPT Presentation
Transcript of Crop Sensors to Control Variable-Rate N Applications: Five Years of On-Farm Demonstrations
Crop Sensors to Control Variable-Rate N Applications: Five Years of On-Farm DemonstrationsPeter Scharf, Kent Shannon, Harlan Palm, Ken Sudduth, Newell Kitchen and Scott Drummond, Univ. of Missouri and USDA-ARS
Introduction• Optimal N rate often varies
widely within & among fields• Weather has a large influence on
optimal N rate•Static properties can’t predict
• Color & reflectance of crop is strongly related to N status & need
Methods• Identify producers/retailers with:
• Interest• Sidedress/topdress equipment• Controller with serial input
• Develop algorithm to convert sensor values to N rates
• Develop control software• Make sensor brackets• Apply high-N reference area• Apply in-season N
• Producer rate and sensor variable-rate side by side
• Minimum 3 replications
sensorssensors
Computer in cab reads sensors, calculates N rate, directs controller
Controller runs ball valve to change fertilizer rate
Locations of sensor demonstration fields 2004-2009
Period#
Fields
Effect of sensor N management* on:
Yield N rate Profit
Mg ha-1 Kg N ha-1 $ ha-1
2004-2007 41 0 -27 +302008 12 +0.6 +18 +72*Effect is calculated relative to an in-season N application whose rate was chosen by the producer
Lessons learned• A good high-N reference
area/value is critical• Sensor values drift—need a
solution• Timing is the biggest issue to
producers
0
50
100
150
200
250
0.8 1 1.2 1.4 1.6 1.8
Visible/near infrared relative to high-N plots
Opt
imal
sid
edre
ss N
rat
e
Turning a sensor reading into an N rate
Cropscan, Crop Circle V6-V7(line basd on data points shown)
Crop Circle V8-V10
Greenseeker V8-V10Greenseeker V8-V10Greenseeker V6-V7Greenseeker V6-V7
