Wheat at our research plots is at Feekes 4/5 and getting closer to jointing with the warmer weather approaching. Feekes 5 (Zadocks 30) is the recommended stage for an application of N to small grains, as this is right before the period of maximum N uptake by the crop. The application at Feekes 5 will help with seed head formation. If nodes are observed above ground when scouting, the wheat has passed Feekes 5 and N applications should be made as soon as possible.
Researchers at Virginia Tech have shown that tissue N content at Feekes 5 is a good indicator of how much additional N is needed to meet the nutritional needs of the crop. A quick tissue test will tell you how much N to apply at this time (Table 1), regardless of whether this is your first or second spring application to small grains.
Table 1. Nitrogen rate recommendations for single or split spring applications to small grains based on tissue N content. Based on research conducted by Virginia Tech scientists.
|Tissue N Content (%)
|Recommended Spring N Rate at Feekes 5 (lb/acre)
There are some additional considerations before you apply N to small grains. The University of Delaware recommends total N applications of 80-120 lbs/acre for wheat and 60-90 lbs/acre for barley. The higher end of the UD range is for sandy soils or fields receiving a single spring N application. If you do not base your Feekes 5 application of N on a tissue test, then you should adjust the N rate by subtracting the rate of N applied during the previous fall to promote fall tillering or at green up in early spring to help with tillering.
Do NOT apply N at rates exceeding 120 lb/ac for wheat and 100 lb/ac for barley, as excessive N can result in lodging and yield loss, as well as N leaching. Also, avoid making N applications once the small grain crop is at or past Feekes 7 (Zadocks 32), as crop response to N at that point is minimal.
Check your small grain fields now and make final N applications soon to maximize the potential of your small grain crop.