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Nafziger, Emerson D. Yoder, Brian H. 2019-02-06T19:36:45Z 2019-02-06T19:36:45Z 2018-12-14 2018-12 Delaying some of the N supplied to the corn crop is considered a way to increase N uptake and yield and to limit N losses, but the length of the delay may increase the risk of yield loss. We conducted a 3-year experiment at Urbana, Illinois in which half of the N (112 kg N ha-1) was injected as UAN at planting and the other half or all (224 kg N ha-1) of the N was dribbled UAN next to the row, at each of eight stages ranging from V3 to R3. In corn following soybean, when half of the N was applied at planting, the other half could be applied as late as R2 without significant yield loss, and application at R3 produced 92% of yield that the treatment with the second application at V3 did. Delaying application of all 224 kg N ha-1 through V15 did not decrease yield significantly, but yield declined by 12, 19 and 37% with application at VT, R2 and R3, respectively. In corn following corn, delaying the second half of the N to R3 produced 96% of the yield that the second application at V3 did, and none of the delayed timings lowered yields significantly. Delaying all the N to V9 did not significantly decrease yield, but yield thereafter decreased as the delay increased, from 11% less at V12 to 42% less at R3. Without N at planting, N needed to be applied by mid-vegetative stages to prevent yield loss, but when half the N was applied at planting, there was surprisingly little yield loss from delaying application until past pollination. SPAD readings showed that the split-N treatments were able to recover their healthy leaf color no matter how late N was applied, but with no N at planting, plants could not regain their full leaf color (or yield) if N was applied later than mid-vegetative stages. Our results indicate that even a lengthy delay in application of N can result in full yields, especially when half of the N is applied early. This application window is shortened if all of the N is delayed, in which case application should be made before plants reach mid-vegetative growth stages. Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2019-02-05 without embargo terms The student, Brian Yoder, accepted the attached license on 2018-12-13 at 16:10. The student, Brian Yoder, submitted this Thesis for approval on 2018-12-13 at 16:25. This Thesis was approved for publication on 2018-12-14 at 10:05. DSpace SAF Submission Ingestion Package generated from Vireo submission #13320 on 2019-02-05 at 11:16:17 Made available in DSpace on 2019-02-06T19:36:45Z (GMT). No. of bitstreams: 2 YODER-THESIS-2018.pdf: 604010 bytes, checksum: b0806b8ec959439ac283da954aa2e289 (MD5) LICENSE.txt: 4208 bytes, checksum: ecdba6ed0724884855b71dc3b5b7fed7 (MD5) Previous issue date: 2018-12-14 application/pdf http://hdl.handle.net/2142/102524 en Copyright 2018 Brian Yoder Corn Nitrogen Corn yield following a delayed application of nitrogen text text Crop Sciences Crop Sciences University of Illinois at Urbana-Champaign Thesis M.S.