Locations Efaw Lake Carl Blackwell Haskell

1. Effect of Delayed Nitrogen Fertilization on Corn Grain Yields Years 2005, 2006 Locations Efaw Lake Carl Blackwell Haskell • Objectives: • To determine the minimum preplant N fertilizer needed to achieve maximum yield if sidedress N fertilizer is applied later in the season. • 2) To determine how late sidedress N can be applied without decreasing grain yields.

3. Grain yield as a function of N application timing SED = 0.6 LCB, 2005

4. Grain yield as a function of N application timing SED = 2.0 LCB, 2006

5. NUE as a function of N application timing LCB, 2005

6. NUE as a function of N application timing LCB, 2006

7. Conclusions • Grain yields decreased when no preplant N was applied and sidedress N was delayed until VT • Recommend preplant N followed by N application at or before V10. • Window of opportunity for mid-season N application: V6 – V10.

8. Aboveground N Accumulation as Function of Time in Corn Years 2006 Location Lake Carl Blackwell Objectives: 1) To establish the amount of nitrogen accumulated in corn over the entire growing season under different levels of N fertilizer.

9. Nitrogen Uptake of Corn at Different Growth Stages at Lake Carl Blackwell, 2006.

10. Summary • Maximum N uptake occurred at growth stages V12 from treatments receiving N fertilizer. • N uptake continued to increase until VT in plots receiving no fertilizer N.

11. Effect of Delayed Emergence on Corn Grain Yields Years 2005, 2006 Locations Lake Carl Blackwell Efaw Objectives: 1) To determine corn grain yield reduction as a function of interplant competition arising from delayed emergence. 2) To evaluate yield levels associated with 3 plant sequences, with and without delayed emergence.

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19. Conclusions Delayed emergence reduces corn grain yields Greater than 5 days delay - significant yield reduction (homogeneity of plant stands) There was a linear reduction in yield with each day of delayed planting Plants delayed by 2,5, and 8 days continued to compete with border plants. By 12 days these plants competed less with border plants.

20. Effect of Altered Nitrogen Distribution on Corn Grain Yield Years 2005, 2006 Locations Lake Carl Blackwell Efaw Objectives 1) To determine the application resolution at which N competition influences corn grain yield 2)To determine the N application resolution at which corn grain yields are maximized.

21. Treatment Structure * 62 kg ha-1 for dryland and 123 kg ha-1 for irrigated

22. Sidedress N Distribution Scenarios Center Plant of the Row Distributed in the Entire Row By-Plant

23. Grain Yield at LCB, 2005 and 2006

24. Grain Yield at Efaw, 2005 and 2006

25. Evaluating Nitrogen Competition Across Rows in Corn Years 2005, 2006 Locations Lake Carl Blackwell Objective To evaluate alternate row N placement on corn grain yield.

26. Treatment Structure

27. Grain Yield, 2005 and 2006

28. Figure 1. Grain yield of corn plants where sidedress N fertilizer was applied in the first 3 rows only, 2005. First 3 Rows Fertilized Last 2, 0-N

29. Figure 2. Grain yield of corn plants where sidedress N fertilizer was applied in the first 3 rows only, 2006. First 3 Rows Fertilized Last 2 Rows, 0-N

30. Effect of Nitrogen Fertilizer Rate and Placement on Corn Grain Yield Year 2006 Locations Lake Carl Blackwell Haskell Objectives 1) To evaluate the use of directed stream application at the base of the plant using UAN versus dribble surface bands applied in the middle of the row. 2) To evaluate the use of directed stream application at the base of the plant, and by-plant using UAN versus dribble surface bands applied in the middle of the row.

31. Treatment Structure

32. Corn grain yield at LCB and Haskell, 2005 and 2006

33. Corn NUE% at LCB and Haskell, 2005 and 2006.

34. CORN OFIT Year 2004, 2005, 2006 Locations Lake Carl Blackwell Efaw Perkins Objectives 1) To determine the nitrogen fertilization optimization algorithm that will be used to estimate N rate for optimum corn growth. 2) To determine optimum resolution to treat field spatial variability in corn.

35. Treatment Structure

36. Results Common Flat Rate versus Algorithms at Efaw site from 2004-2006 With Preplant Nitrogen

37. Results Common Flat Rates versus Algorithms at Efaw site from 2004-2006 Without Preplant Nitrogen

38. Results RICV- versus RI-NFOA at Efaw from 2004-2006. With Preplant N

39. Results On-average * CFR : Common Flat Rate

40. Summary • NUE was generally higher when mid-season N rates were generated by NFOA compared with flat farmer rates. • Increased NUE was attributed to the lower N rates applied.

41. Summary • Use of RI NFOA resulted in a higher increase in NUE than RICV NFOA. • There was limited benefit of treating spatial variability at the high resolution (0.34 m2, RICV algorithm). • NFOA approaches didn’t project high N rates that did not affect increased yields.