Ramp%20Calibration%20Strip%20(RCS)%20Technology%20for%20Determining%20Mid-Season%20N%20Rates%20in%20Wheat%20and%20Corn

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Ramp Calibration Strip (RCS) Technology for
Determining Mid-Season N Rates in Wheat and Corn

• Clint Mack, John Solie, Randy Taylor, Jim
  Schepers, Brian Arnall, John Solie, Gyles
  Randall, Clint Dotson, Jeff Vetsch, Kefyalew
  Girma, Robert Mullen, Newell Kitchen, Kent
  Martin, Paul Hodgen, and Bill RaunNUE
  Collaborative Group Tuesday, 14 November
  2006 - 945 AM

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Rationale

• Refinement of the Calibration Stamp (AJ 2005)
• RCS superimposed on the farmer preplant N
  practice
• Allows producers to examine plant responsiveness
  over the range of rates to determine the optimum
  topdress N rate. 
• Point where visual growth differences no longer
  exist is the topdress N Rate
• or lowest rate where there are no longer any
  visual differences 
• Recording distance as you walk the RCS since
  distance is associated with a predetermined N. 
• Assumes that we can catch up or achieve maximum
  yields from mid-season N applications, and that
  yield potential was not severely restricted by
  early season N stress. 

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Need for Sidedress N

• Schmidt et al. (2002) AJ 94798 recommended
  sidedress N application to improve NUE
• Blackmer et al. (1989) JPA 2103 delaying N
  fertilization until mid-season allowed for more
  accurate determination of crop needs (in-season
  soil test)
• Wuest and Cassman (1992) AJ 84689 higher N
  recovery when fertilizer is applied mid-season

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Gyles Randall, 2006Problems - sidedress N

• 1. We have limited equipment for the later SD
  applications.
• 2. We see more and more 20 and 15 rows, which
  poses a huge problem.
• 3. Quick N uptake is problematic, depending on
  rainfall.
• 4. Will yield-drag occur if some hidden N
  deficiency occurs around the VT and R1 stages.
• Farmers see these challenges as one big RISK, and
  risk in todays environment plays a large role in
  farmers decision making.

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Ramp Calibration Strip
2006 RCSConfiguration
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Woodward County
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Ramp Configuration

• Controller Custom Made
• Nozzles 1, 2, 4, 8X (on/off)
• Software Custom
• Speed 5 mph
• Rates 0-195 lbs/ac, 13.3 lb/ac increments
• Ramp Interval 10ft to infinity
• Want to work toward using commercial components
  (IPAQ, Raven controller)
• Specifications www.nue.okstate.edu/Index_RI.htm

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Average, 8 Farmer Sites, 04-05

• N Rate Yield GP NUE
• kg/ha kg/ha /ha
• Check 0 2477 293 -
• SBNRC 43 2644 304 37
• RCS 77 2791 303 30
• Farmer Practice 127 2911 287 16
• SED 379

2005 0.59 kg N 0.12 kg grain (0.27/lb
N, 3.40/bu) SBNRC (Sensor Based Nitrogen Rate
Calculator)
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Average, 11 Farmer Sites, 05-06

• N Rate Yield GP NUE
• kg/ha kg/ha /ha
• Check 0 3235 560 -
• SBNRC 39 3281 556 38
• RCS 63 3243 528 24
• Farmer Practice 113 3426 510 22
• SED 339

2006 0.84 kg N 0.18 kg grain (0.38/lb N
4.86/bu) SBNRC (Sensor Based Nitrogen Rate
Calculator)
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Ramp Calibration Strip

• Walk it off
• Or use Hand-Held Sensor

0 N
195 N
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Winter Wheat, Enid, 2005
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Winter Wheat, Drummond, 2005
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• RCS Data Sheet

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On-Farm Progress

• 2004 300 N Rich Strips
• 2005 gt 1000 N Rich Strips (SBNRC)
• 2006
• 500 Ramps in Farmer Fields
• 1500 N Rich Strips with one Fertilizer Dealer
• Wheeler Brothers
• gt 2000 total N Rich Strips in 2006

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• RAMPS, 2006

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Issues

• Corn Weakness - you don't know whether or not
  this rate will "run out" later in the season. 
• Long-term experiments have shown that there are
  years where the check plot (No N Fertilizer ever
  applied) produced near maximum yields. 
• Have years where the demand for fertilizer N is
  less (and highly dependent on the environment),
  and other years where it is cool and dry and the
  demand for fertilizer N is greater. 
• RCS approach can help to determine how much the
  environment delivers and that is variable year to
  year  

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www.nue.okstate.edu