1. Sensors and Fertility Management
Randy Taylor
Extension Engineer, Machinery Systems
Biosystems and Ag Engineering

2. Reference Strips for Nitrogen
Oklahoma State has recommended nitrogen reference (rich) strips to assist in season nitrogen management for corn and wheat
Recently OSU has implemented Ramped Calibration Strips (RCS) to allow visual and sensor assessment of nitrogen management

3. Ramp Program
586 farmer’s fields have had Ramp Calibration Strips placed in them

4. Documenting Impact Each RCS has an associated contact person who will
collect sensor data.
complete the data sheet.
Many were lost due to grazing, drought, or freeze.

5. What is a RCS?

6. Reading Ramp Strips

7. Can the Sensor Perform?

8. Recommendations Statewide Garfield County SBNRC  22 lbs/ac
RCS  54 lbs/ac
Garfield County
SBNRC  27 lbs/ac
RCS  60 lbs/ac

9. Statewide Data Summary
117 fields with sufficient data to draw inferences
Applied N was 73% of “typical” topdress rates
Applied N was 147% of RCS recommendation
Applied N was 290% of the SBNRC recommendation

10. RCS Applicators

11. RCS Applicator Components

12. We constructed a sprayer with sets of 4 StreamJet nozzles from TeeJet per location. Nozzles are spaced on 24 inch centers. The four nozzles are an 01, 02, 04, and 08. We are using a design pressure of 40 psi.

13. Nozzle Control RCS Starts Each step lasts approximately 10 feet.
RCS Ends
GPM flow rates are for 28% fertilizer solution.

14. Rendel Farms Applicator
7 tip sets on 20” center
4 solenoid control valves
50 gallon poly tank
PTO-driven roller pump
1” supply line
½” spray line

15. Johnson Farms Applicator

16. Boom Width Ramps
3 nozzles together to make a 5 ft. section of one rate.
A challenge is the large rate steps at the higher end.

17. EXTENSION AND ANALYSIS OF THE RAMP CALIBRATION STRIP FERTILIZATION STRATEGY
D.E. Edmonds, D.B. Arnall, B. Chung, M.C. Daft, K. Girma, C.R. Dotson, B.B. England, S.L. Holtz, C.J. Mack, W.R. Raun, J.B. Solie, R.K. Taylor, B.S. Tubaña, P.L. Turner, O.S. Walsh, D.L. Zavodny
ASA-CSSA-SSSA
2007
New Orleans, LA

18. Crop production directly related to availability of N
INTRODUCTION
Nitrogen Use Efficiency (NUE) in the world for cereal grain production ~ 33%
Crop production directly related to availability of N
Need methodologies that consider:
Crop production practices
Aesthetic qualities
Economical analysis
Environmental stewardship

19. Ramp Calibration Strip Fertilization Strategy
Concept of visually evaluating plots with incremental rates of pre-plant N
Identify minimum N rate required for maximum production

22. RAMP Calibration Strip
N Rate, kg/ha
224 34 17
224

23. March 2007, The Furrow, Larry Reichenberger

24. Implement & Evaluate the RCS strategy in the following crops:
PURPOSE OF STUDY
Implement & Evaluate the RCS strategy in the following crops:
Alfalfa
Bermudagrass
Corn
Cotton
Grain Sorghum
Extend the RCS strategy in the following crop:
Wheat

25. MATERIALS & METHODS Alfalfa, Grain Sorghum Alfalfa Grain Sorghum
Experiment site – R.L. Westerman Irrigation Research Center located west of Stillwater, OK.
Alfalfa, Grain Sorghum
4 replications of 5 treatments + 1 or 2 N-Ramp(s)
Complete Randomized Block Design
Alfalfa
Trt.
N applied after each cutting (kg ha-1) 1. 2.
22.4 3.
44.8 4.
RCS Visual 5.
RCS Sensor
Grain Sorghum
Trt.
Pre-Plant N (kg ha-1)
Mid-Season N (kg ha-1) 1. 56 2. 84 3.
168 4.
RCS Visual 5.
RCS Sensor

26. (N applied mid-season)
Treatments
(N applied mid-season) 1.
0 kg N/ ha 2.
84 kg N/ ha 3.
168 kg N/ ha 4.
RCS Visual 5.
RCS Sensor
Grain Sorghum Application of N-Ramp Strategy R.L. Westerman Irrigation Research Center at Lake Carl Blackwell
15.25 m
3 m
6 m
1.5 m
52 m
4.25 m
Rep. 1
Rep. 2
Rep. 3
Rep. 4 6
7.5
13.5 15 21
22.5
28.5 3 9 12
29 m N - R A M P 4 1 3 5 2 N E S W 4 5 2 3 1 4 1 3 5 2
Plot size: 3 m x 6 m
Alley: 1.5 m
4 replications
Ramp: 4.25 m x 52 m 2 4 5 3 1

27. ALFALFA – RESULTS Alfalfa Inconclusive for 2007 Average Yields
Limited number of cuttings
Average Yields
1st Cutting
5607 kg ha-1
2nd Cutting
3734 kg ha-1
Alfalfa
Trt.
N applied after each cutting (kg ha-1) 1. 2.
22.4 3.
44.8 4.
0 - RCS Visual 5.
0 - RCS Sensor

28. GRAIN SORGHUM – RESULTS
Average Yields
Grain Sorghum
Trt.
Pre-Plant N
(kg ha-1)
Mid-Season N (kg ha-1)
Total N
Yield
Gross Return
($ ha-1) 1. 56
2776
290 2. 84
140
5033
488 3.
168
224
6166
545 4. 73
RCS Visual
129
4783
468 5.
RCS Sensor
112
5370
558
Gross Return: N cost = $1.01 / kg, Sorghum = $0.125 / kg

29. WHEAT – EXTENSION OF N-RCS APPROACH
Fall 2006
N-Ramps placed in 586 farmer fields throughout Oklahoma covering a service area of 81,000 hectares

30. Garfield County Ramp Strips
March 22, 2007

31. February/March 2007 County Extension Agents Sensed N-Ramps
Provided top-dress N recommendations to producers
Collected data for submission to N-Ramp extension team

32. EXTENSION OF N-RCS APPROACH IN WHEAT – RESULTS
Average Typical Top-Dress N Rate
125 kg N / ha
Average RCS N-Recommendation
60 kg N / ha
Average Actual Top-Dress N Applied
90 kg N / ha
50 % more than the RCS recommendation
73 % of typical top-dress N rate
Represents savings of $ 4.38 ha-1
Represents total savings of $ 354,375

33. CONCLUSIONS
Current practices for making mid-season fertilizer N recommendations in most crops are not consistent from one region to the next
The N-Ramp Approach:
Using automated gradients of pre-plant N fertilizer to determine mid-season N rates based on plant response
Applied methodology integrating farmer input and insight in the decision making process
Provides visual mid-season alternative approach for N fertilization

34. QUESTIONS www.nue.okstate.edu/
EXTENSION AND ANALYSIS OF THE RAMP CALIBRATION STRIP FERTILIZATION STRATEGY
QUESTIONS
DANIEL E. EDMONDS