Timing Spring Nitrogen Application for Wheat
Wet weather seems to be a common occurrence for us this winter here in Sampson County. This is not necessarily favorable for the wheat that was planted during the fall. Wheat is generally in the field for 8 months and is often planted in soils that drain easily. This creates a favorable scenario for nutrient leaching, which puts stress on the wheat crop. Plants suffering from N deficiency are pale in comparison to healthy plants due to the breakdown in chlorophyll production. Symptoms of N deficiency usually appear on the oldest leaves first with the new leaves remaining relatively green. The older leaves become paler than newer leaves with yellowing beginning at the tip and gradually merging into light green further down the leaf.
Timing a nitrogen application correctly can allow a sufficient amount of tillers to form and improve your yields when harvest comes around.
As January rolls around, it is time to start planning for topdressing in fields that may be nitrogen deficient to maximize potential yield at harvest. In order to know whether or not you should apply nitrogen, it is crucial to count the number of tillers per square foot. A tiller is considered any stem that has three leaves or more at the time your counts are done. If you have 7.5-inch row spacing, then 19 inches of row length (only one drill row) equals one square foot. The number of 3 leaf tillers per 19 inches of row feet multiplied by 12 divided by 7.5 will give you the number of tillers per square foot.
Example: if you count 44 3-leaf tillers per row foot x 12 = 528, then divide by row spacing of 7.5 inches, you would have approximately 70 tillers per sq ft.
- Wheat fields without any signs of N deficiency showing 50 or more 3 leaf tillers in late January/early February can wait until a topdress application is made around Growth Stage 30. If the field has 50 or more tillers but is showing signs of N deficiency, you may apply 30-40 units of N in late January/ early February and the rest at Growth Stage 30.
- Wheat fields with 30-49 3 leaf tillers per square foot in late January/early February can receive a split topdress N application. Apply approximately half in late January and approximately half at Growth Stage 30.
- Wheat fields with less than 30 3-leaf tillers per square foot in late January/early February are up to the grower’s discretion. You should consider potential input costs going forward versus potential income. At Growth Stage 30, tiller production stops and stem elongation begins.
For more information, contact your local North Carolina Cooperative Extension office at (910) 592-7161.