Richard Taylor, Extension Agronomist; rtaylor@udel.edu
With the onset of somewhat warmer temperatures, winter wheat is beginning to advance in its stage of development rapidly. At least in northern Delaware, many wheat fields appear to be between Feeke’s growth stage 5, leaf sheaths lengthened and erect, and stage 6 where the first node of stem elongation is felt above the soil surface. This is the last stage where we suggest that a nitrogen (N) application will produce a substantial yield increase if the plants are deficient in N. Later applications tend to increase the protein content of the finished grain but do not give you the yield increase seen with the early application of N fertilizer.
We have seen increases in yield (5 to 8 percent) for split applications of nitrogen and this increase appeared to be relatively independent of the total rate of N applied. The increase was found when the total application was 60 lb N/acre as well as when the total application was 140 lb N/acre. If you were successful earlier this spring in applying the first split of N to the field and did not reach the maximum rate allowed by your nutrient management plan, an additional application prior to growth stage Feeke’s 6 should provide you with a yield increase. Unless you have not been able to apply any N to the wheat up to this point, avoid traffic on wet fields as the damage done through compaction and rutting of fields can easily add up to the small yield increase seen when N applications are split.