| Table 1. Wheat grain yield response to applied N at fixed rates and rates based on in-season-estimated-yield (INSEY) at six locations, 2003. | ||||||||
| Trt | N rate | Method | Lahoma | Covington | Tipton | Altus | Hennessey | Perry |
| kg ha-1 | kg ha-1 | |||||||
| 1 | 0 | check | 1960 | 3422 | 895 | 2760 | 2760 | 3334 |
| 2 | 45 | mid-season | 3327 | 4266 | 1254 | 2773 | 2987 | 4134 |
| 3 | 90 | mid-season | 4159 | 4550 | 1594 | 2477 | 3120 | 4796 |
| 4 | 90 | 45 pre, 45 mid-season | 4512 | 4896 | 1393 | 2899 | 3378 | 4449 |
| 5 | 45 | pre | 3579 | 4490 | 993 | 2753 | 3264 | 4165 |
| 6 | 90 | pre | 4518 | 4688 | 1465 | 2836 | 3195 | 4430 |
| 7 | (†) | NFOA, 60%NUE | 2697(39) | 3800(19) | 1078(25) | 2836(17) | 3162(39) | 3781(17) |
| 8 | (†) | 45 pre, NFOA, 60%NUE | 4751(62) | 4550(21) | 1519(33) | 2867(18) | 3138(10) | 4606(22) |
| 9 | (†) | mid-season, Flat NFOA | 2817(39) | 3554(19) | 1033(25) | 2647(17) | 2981(39) | 3737(17) |
| 10 | (†) | 45 pre, Flat NFOA | 4613(62) | 4575(21) | 1418(33) | 2899(18) | 3384(10) | 4273(22) |
| 11 | (†) | NFOA 40%NUE | 4039(71) | 4184(29) | 1185(39) | 2672(26) | 3145(41) | 4058(28) |
| 12 | (†) | Spring NFOA 60%NUE | 4172(63) | 3775(26) | 1160(41) | 2848(29) | 2899(40) | 4273(16) |
| 13 | (†) | 45 pre, Spring NFOA 60%NUE | 4695(44) | 4688(13) | 1336(26) | 2807(12) | 2968(21) | 4083(9) |
| RINDVI | 1.48 | 1.25 | 1.44 | 1.13 | 1.34 | 1.24 | ||
| RIHARVEST | 2.3 | 1.37 | 1.64 | 1.03 | 1.16 | 1.33 | ||
| YP0 (avg.) 0N preplant | 2353 | 1910 | 1439 | 2306 | 3913 | 1950 | ||
| YP0 (avg.) 45N preplant | 3268 | 2212 | 1816 | 2562 | 4936 | 2320 | ||
| YP0 (avg.) 90N preplant | 4101 | 2599 | 2371 | 2942 | 6140 | 2477 | ||
| Yield (avg.) | 3834 | 4265 | 1256 | 2775 | 3106 | 4163 | ||
| CV trt 1 | 14 | 25 | 30 | 9 | 24 | 15 | ||
| CV trt 6 | 13 | 23 | 24 | 10 | 20 | 10 | ||
| SED | 309 | 217 | 91 | 118 | 163 | 269 | ||
†-average mid-season N rate applied
RINDVI computed by dividing the average NDVI at Feekes 4-6 from treatment 6 by the check (no prelant applied)
RIHARVEST computed by dividing the highest yield of N fertilized plots by the yield of unfertilized control plots
YP0 (avg.) = predicted grain yield from INSEY for treatments 7-13 (prior to fertilization)
Yield (avg.) = Average yield of all treatments, by site
SED-standard error of the difference between two equally replicated means.
OFIT Trials 2001
