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

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

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).

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.

Long term N-P-K Experiments(1969-2004)

Dr. Billy Tucker

Response IndexResponse Indexvariable from year to year in the same fieldvariable from year to year in the same field

1995

RI = 1.2

2004

RI = 1.7

0

1

2

3

4

5

6

1971

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

Year

Gra

in y

ield

, M

g/h

a 0 kg N/ha

112 kg N/ha

1

1.5

2

2.5

3

3.5

4

4.5

19

71

19

73

19

75

19

77

19

79

19

81

19

83

19

85

19

87

19

89

19

91

19

93

19

95

19

97

19

99

20

01

20

03

Year

Re

sp

on

se

Ind

ex Response Index

min: 1.0max: 4.1avg: 1.7

min: 1.0max: 4.1avg: 1.7

Response to Fertilizer NLong-Term Wheat Experiment

Lahoma, OK 1970-2003

0

2

4

6

8

10

12

14

1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Gra

in Y

ield

, Mg

/ha

0-N kg/ha

UAN-180 kg N/ha

Response to Fertilizer N

Mead, NE, 1969-1983

Response to Fertilizer NLong-Term Corn Experiment

Mead, NE, 1969-1983

1

1.5

2

2.5

3

3.5

4

1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983

Res

po

nse

Ind

ex

Prof. R.A. OlsonProf. R.A. Olson

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-m2 grid.

9 separate 1-m2 areas Four corners receive no fertilizer N. Rates of 22, 45, 67, 90, and 112 kg N ha-1 occupy the

other 5

CalibrationStamp

80

100

40

0

60

0

020

0

lb N / acre

Blue Dye, 30 ml L-1

Automated Calibration Stamp

Pumpless pressurized spray system19L auxiliary air tank11.3L Spartanburg stainless steel tankProgrammable logic controllerRemcor solenoid valves

Winter WheatCalibration Stamp applied in DecemberVisual Interpretation in March

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

December

MarchCalibrationStamp

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 Rate NDVI N Rate NDVI N Rate NDVI 100 0.80 100 0.76 100 0.69 80 0.79 80 0.74 80 0.68 60 0.78 60 0.68 60 0.69 40 0.65 40 0.55 40 0.67 20 0.55 20 0.45 20 0.68 0 0.51 0 0.41 0 0.54

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

www.nue.okstate.edu

N Rich Strip (J. Lawles, S. Reed)NTech Industrieswww.ntechindustries.com

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 = $5000Tanks, Controller, Nozzles, Valves, Boom, Programming, Labor = $800

Can be used with on-line Sensor Based N Rate Calculator to improve mid-season N management

GreenSeeker-Red

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

>15 readings 0.4m2

+/- 0.005