1. Automated Calibration Stamp Technology for Improved In-Season Nitrogen Fertilization K. Freeman, R. Teal, C. Mack, K. Martin, B. Arnall, K. Desta, J. Solie, M. Stone, H. Zhang, B. Raun

2. Review  Pre-sidedress nitrate test (PSNT) was an extension of preplant nitrate tests, in-season soil nitrate analysis was used to refine topdress rates (Bundy and Andraski, 1995).  Predicting N mineralized from soil organic matter could lead to improved N fertilizer recommendations (Cabrera and Kissel, 1988).  Mulvaney et al. (2001) found that the concentration of amino sugar N was highly correlated with check-plot yields and fertilizer N response.  Temporal variability strongly influences N supplied by soil organic matter and the demand for in-season N  Pre-sidedress nitrate test (PSNT) was an extension of preplant nitrate tests, in-season soil nitrate analysis was used to refine topdress rates (Bundy and Andraski, 1995).  Predicting N mineralized from soil organic matter could lead to improved N fertilizer recommendations (Cabrera and Kissel, 1988).  Mulvaney et al. (2001) found that the concentration of amino sugar N was highly correlated with check-plot yields and fertilizer N response.  Temporal variability strongly influences N supplied by soil organic matter and the demand for in-season N

3. Review (cont)  In many states, 33 kg N ha -1 is recommended for every 1 Mg of anticipated wheat yield (2 lb N ac -1 for every bushel of expected wheat grain yield)  This strategy explicitly places the risk of predicting the environment (good or bad year) on the farmer  Varvel et al. (1997) employed chlorophyll meter readings to calculate a sufficiency index: in-season N fertilizer applications were made when index values were below 95%.  Sufficiency index < 90% at the V8 growth stage in corn, maximum yields could not be achieved with in-season N fertilizer applications (Varvel, 1997).  In many states, 33 kg N ha -1 is recommended for every 1 Mg of anticipated wheat yield (2 lb N ac -1 for every bushel of expected wheat grain yield)  This strategy explicitly places the risk of predicting the environment (good or bad year) on the farmer  Varvel et al. (1997) employed chlorophyll meter readings to calculate a sufficiency index: in-season N fertilizer applications were made when index values were below 95%.  Sufficiency index < 90% at the V8 growth stage in corn, maximum yields could not be achieved with in-season N fertilizer applications (Varvel, 1997).

4. Review  Normalized difference vegetation index (NDVI) divided by the number of days from planting to sensing used to predict mid-season winter wheat yield potential (OSU)  Response Index: N Rich Strip (sufficient nitrogen but not excess) strip and the adjacent area with the field rate of preplant applied N.  Although systems have been developed to determine midseason N fertilizer topdress recommendations, the need exists for a simple system that cereal grain producers can use to quickly estimate required N topdress rates.  Normalized difference vegetation index (NDVI) divided by the number of days from planting to sensing used to predict mid-season winter wheat yield potential (OSU)  Response Index: N Rich Strip (sufficient nitrogen but not excess) strip and the adjacent area with the field rate of preplant applied N.  Although systems have been developed to determine midseason N fertilizer topdress recommendations, the need exists for a simple system that cereal grain producers can use to quickly estimate required N topdress rates.

5. Long term N-P-K Experiments (1969-2004) Dr. Billy Tucker Long term N-P-K Experiments (1969-2004) Dr. Billy Tucker Response Index variable from year to year in the same field 1995 RI = 1.2 1995 RI = 1.2 2004 RI = 1.7 2004 RI = 1.7

6. Response to Fertilizer N Long-Term Wheat Experiment Lahoma, OK 1970-2003

7. 0 2 4 6 8 10 12 14 196919701971197219731974197519761977197819791980198119821983 Grain Yield, Mg/ha 0-N kg/ha UAN-180 kg N/ha Response to Fertilizer N Mead, NE, 1969-1983 Response to Fertilizer N Long-Term Corn Experiment Mead, NE, 1969-1983 1 1.5 2 2.5 3 3.5 4 196919701971197219731974197519761977197819791980198119821983 Response Index Prof. R.A. Olson

8. Materials and Methods  2003 Honda FourTrax Foreman ES 4-wheeler (433-cc, 127-cm wheel base, 116-cm wide) with a 3-m wide spray boom and a 1-m spacing between nozzles  Modified to deliver a range of fixed N rates as urea ammonium nitrate (28 %N) within a 9-m 2 grid.  9 separate 1-m 2 areas  Four corners receive no fertilizer N.  Rates of 22, 45, 67, 90, and 112 kg N ha -1 occupy the other 5  2003 Honda FourTrax Foreman ES 4-wheeler (433-cc, 127-cm wheel base, 116-cm wide) with a 3-m wide spray boom and a 1-m spacing between nozzles  Modified to deliver a range of fixed N rates as urea ammonium nitrate (28 %N) within a 9-m 2 grid.  9 separate 1-m 2 areas  Four corners receive no fertilizer N.  Rates of 22, 45, 67, 90, and 112 kg N ha -1 occupy the other 5

9. Calibration Stamp

10. 80 100 40 0 0 60 0 0 0 0 20 0 0 lb N / acre Blue Dye, 30 ml L -1

11. Automated Calibration Stamp Pumpless pressurized spray system 19L auxiliary air tank 11.3L Spartanburg stainless steel tank Programmable logic controller Remcor solenoid valves

12. Winter Wheat Calibration Stamp applied in December Visual Interpretation in March

13.  Topdress N rate prescribed by choosing the lowest N rate where no visual differences were observed between it and the highest rate.

14. December March Calibration Stamp

15. Results  Field-specific topdress N rate prescribed by choosing the lowest N rate where no visual differences were observed between it and the highest rate.  N RateNDVIN RateNDVIN RateNDVI  1000.801000.761000.69  800.79800.74800.68  600.78600.68600.69  400.65400.55400.67  200.55200.45200.68  00.5100.4100.54  Field-specific topdress N rate prescribed by choosing the lowest N rate where no visual differences were observed between it and the highest rate.  N RateNDVIN RateNDVIN RateNDVI  1000.801000.761000.69  800.79800.74800.68  600.78600.68600.69  400.65400.55400.67  200.55200.45200.68  00.5100.4100.54

16. http://www.soiltesting.okstate.edu/SBNRC/SBNRC.php www.nue.okstate.edu

18. N Rich Strip (J. Lawles, S. Reed) NTech Industries www.ntechindustries.com

19. Summary  Calibration stamps applied preplant or soon after planting assist in providing visual interpretation of N mineralization + atmospheric N deposition from planting to the time mid-season N is applied, and improved determination of topdress N rates.  Cost: Honda 4X = $5000 Tanks, Controller, Nozzles, Valves, Boom, Programming, Labor = $800  Can be used with on-line Sensor Based N Rate Calculator to improve mid-season N management  Calibration stamps applied preplant or soon after planting assist in providing visual interpretation of N mineralization + atmospheric N deposition from planting to the time mid-season N is applied, and improved determination of topdress N rates.  Cost: Honda 4X = $5000 Tanks, Controller, Nozzles, Valves, Boom, Programming, Labor = $800  Can be used with on-line Sensor Based N Rate Calculator to improve mid-season N management

20. GreenSeeker-Red Average NDVI = 0.816, standard deviation in NDVI = 0.0056 Distance to target: 0.8-1.2m Average NDVI = 0.816, standard deviation in NDVI = 0.0056 Distance to target: 0.8-1.2m

21. >15 readings 0.4m 2 +/- 0.005