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

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

2006-07 Ramp Program 586 farmer’s fields have had Ramp Calibration Strips placed in them

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.

What is a RCS?

Reading Ramp Strips

Can the Sensor Perform?

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

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

RCS Applicators

RCS Applicator Components

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.

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

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

Johnson Farms Applicator

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.

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

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

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

RAMP Calibration Strip 224 0 17 34 51 68 85 112 129 N Rate, kg/ha 224 34 17 224

March 2007, The Furrow, Larry Reichenberger

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

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

(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

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

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

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

Garfield County Ramp Strips March 22, 2007

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

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

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

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