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I NITIATION OF Y IELD P OTENTIAL T RIALS & D EVELOPMENT OF Z IMBABWEAN A LGORITHMS

This workshop in Harare, Zimbabwe aims to develop algorithms for precision sensing and implement yield potential trials to improve nitrogen use efficiency in cereal grain production. The workshop will focus on the concept of visually evaluating plots with incremental rates of pre-plant nitrogen to identify the minimum nitrogen rate required for maximum production.

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I NITIATION OF Y IELD P OTENTIAL T RIALS & D EVELOPMENT OF Z IMBABWEAN A LGORITHMS

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  1. INITIATION OF YIELD POTENTIAL TRIALS & DEVELOPMENT OF ZIMBABWEAN ALGORITHMS Precision Sensing Extension Workshop January 8, 2008 Harare, Zimbabwe, Africa M. Cody Daft and Daniel E. Edmonds Graduate Research Assistants Plant & Soil Sciences

  2. 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

  3. 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

  4. RAMP CALIBRATION STRIP 2006 – 2007 RCSConfiguration

  5. RATIONALE • 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.

  6. WHY THE RAMP WORKS • How can the RAMP be used to identify the appropriate rate? • Agronomic Assumptions “Even when early season N stress was present (0-N preplant), N applied topdress at Feekes 5 resulted in maximum or near maximum yields at 4 of 6 site-year combinations when compared to other treatments receiving both preplant and topdress N.”

  7. NEED FOR MID-SEASON NAPPLICATION • Blackmer et al. (1989) JPA 2:103 delaying N fertilization until mid-season allowed for more accurate determination of crop needs (in-season soil test) • Wuest and Cassman (1992) AJ 84:689 higher N recovery when fertilizer is applied mid-season

  8. RAMP CALIBRATION STRIP • Walk it off • Or use Hand-Held Sensor 0 N 195 N

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

  10. March 2007, The Furrow, Larry Reichenberger

  11. CONCLUSIONS • 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 • Farmers see these challenges as one big RISK, and risk in today’s environment plays a large role in farmer’s decision making.

  12. CONCLUSIONS CONTINUED 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

  13. RAMP CALIBRATION STRIP FERTILIZATION STRATEGY QUESTIONS or COMMENTS www.nue.okstate.edu/ Precision Sensing Extension Workshop Zimbabwe, Africa

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