ISSUE 6 June 9, 2005
TOPDRESSING N ON SPRING WHEAT AND DURUM
Topdressing N on fields with inadequate N can be helpful if:
1. The field can be entered with ground spray equipment.
2. It rains shortly after application at least ˝ inch.
3. The small grains are not too advanced in maturity.
The quantities needed for yield enhancement are at least 30 lb N, and sometimes more depending on preplant N supplied. There are 3 lb N in each gallon of 28%. Therefore, while aerial application has its place, this is not one of those places.
Application should be made with stream nozzles or stream-bars. On taller wheat, stream nozzles are preferred because the stream-bars have a habit of catching on foliage and breaking off sometimes. However, they do work well and with care can last a long time. Because the stream application is not a foliar treatment, rather a concentrated soil band in effect, it needs rain to work it into the soil. So far, this has not been a problem for those who have applied topdress this season in most of the state. But this is North Dakota, so who knows what will happen this week.
If rain doesn’t fall before the wheat reaches jointing, the N may help boost protein, but will do little to increase yield. Application is best made at 4-5 leaf stage, with a 6-leaf application effective only if rain chases the applicator out of the field. Earlier application is better than later application.
To boost protein, it is better to wait until right after pollination at the watery-ripe stage of growth and apply a broadcast foliar treatment of 10 gal 28% mixed half and half with water and apply during the cool of the day. This has resulted in a protein boost from ˝ to 1 % in ND trials, with ˝ % being more common.
Dr. Dave Franzen
NDSU Extension Soil Specialist