1. By-Plant N Management Oklahoma State University

4. Scale

5. Ames, IA

7. Stillwater, OK

9. By-Plant N Management

10. Paul Hodgen, Jim Schepers, 15N 60% of by-plant N accounted for in individual plants

14. Ames, Iowa

15. Shelton, NE

16. Ames, IA

17. Agron. J. 97:1603-1611 At the sites with the highest average corn grain yield (11478 and 14383 kg ha -1, Parana Argentina, and Phillips, NE), average plant-to-plant variation in yield was 4211 kg ha -1 (67 bu ac -1 ) and 2926 kg/ha (47 bu ac - 1 ), respectively. As average grain yields increased, so too did the standard deviation of the yields obtained within each row. This clearly indicates that by-plant variability can be expected in high and low yielding environments. Furthermore, the yield range (maximum corn grain yield minus the minimum corn grain yield per row) was found to increase with increasing yield level. This work shows that regardless of yield level, plant-to-plant variability in corn grain yield can be expected and averaged more than 2765 kg ha -1 over sites and years.

18. Causes for Delayed and uneven emergence variable depth of planting double seed drops wheel compaction seed geometry within the furrow surface crusting random soil clods soil texture differences variable distance between seeds variable soil compaction around the seed insect damage moisture availability variable surface residue variable seed furrow closure volunteer early season root pruning (disease, insect)

19. 5-Plant Sequence

20. Formula

22. Treatment Structure TrtPre-plant kg ha -1 Top-dress (V8-V10) kg ha -1 Method 14522By plant at base 24522By row at base 34522DSB at center 445 By plant at base 545 By row at base 645 DSB at center 74590By plant at base 84590By row at base 94590DSB at center 1045180By plant at base 1145180By row at base 1245180DSB at center 1300- 14450Broadcast 152250Broadcast

23. Methods of placement By-plantBy-row Between rows

24. SED = 1.15

25. SED = 0.55

26. By-plant fertilization method had slightly higher yields in five out of six site-years, especially at the low N rate. In five of six site years the middle N rates of 67 and 90 kg N ha -1 showed grain yields as high as or higher than the 135 and 225 kg N ha -1 N rates. Results