Post-anthesis N application studies North Dakota, region and elsewhere

Carrington, 1988-1991, G. Endres and B. Schatz.

Fertilizers were applied preplant for a 40 bushel/acre yield goal. Foliar N was applied immediately after anthesis (flowering, about 7-10 days after heading). Foliar N source was 28% at a total liquid volume of 20 gal/acre (28% = 3 lb N/gal, so lower rates were diluted to 20 gal total volume). Greatest protein increase was provided with 30 lb N (10 gal/acre 28%). Additional N increased protein in some years, but with less efficiency. Under irrigation, yield was depressed at N rates greater than 30 lb N/acre.

Protein and yield with foliar N rates applied post-anthesis, Carrington, 1988-1991, dryland.           

Protein and yield with foliar N rates applied post-anthesis, Carrington, 1988-1991, irrigated.               

Carrington Post-Anthesis survey, 1993. G. Endres and B. Schatz.

• The survey compiled responses from 27 growers using post-anthesis N strategies during 1993. Thirty-two growers used 28%, two used Nisol. Acres treated ranged from 5 to 1,750, with a mean of 275.
• Twenty-nine were applied by air and one by ground.
• Rates of N ranged from 10-50 lb/acre (60% used 30 lb/acre, 15% used 15 lb/acre). Four growers diluted their fertilizer and 26 did not.
• 89% of growers applied during the morning or evening hours. Temperature averaged 55- 73 degrees. One-third of the growers received rain within 24 hours (0.03-0.25 inches).

Flag-leaf damage

• 0-5%, 73% of growers
• 10-35%, 23% of growers
• 80-90%, 3% of growers

Yield differences

Range- -7 bu to +15 bu/acre, average 0.2 bu/acre

Protein differences

Range- -0.4% to +2.2%, average 0.7 %

Optimal timing for foliar N for protein enhancement is directly post-anthesis. Efficiency of N uptake and transfer into the grain rapidly declines following the time directly after anthesis and before. Under the right circumstances, as much as 1% protein increase from about 30 lb N/acre can be realized. Care should be taken to prevent undue burning of leaves.

- Notes from Gooding, M.J. and W.P. Davies. 1992. Foliar urea fertilization of cereals: a review. Fertilizer Research 32:209-222.

Crookston, MN. J. Wiersma, M.A. Hanson, E.L. Peters, and R.J. Bouvette.1993. Trial used four varieties of spring wheat. Foliar N was supplemental to 150 lb N from fertilizer preplant and soil test N.

N rates of 30, 60, 90 and 120 lb N/acre were sequentially applied every fourth day (7.5, 15, 22.5, and 30 lb N/application) starting 7 days after anthesis.

The sequential 30 lb total N rate provided 0.5% greater protein; sequential 60 lb total N rate 1%; sequential 90 lb total N 2%; sequential 120 lb total N 2.5%. All varieties exhibited similar responses to foliar N for protein increase.

Yields tended to decrease slightly at sequential rates above 30 lb N/acre.

H. Woodard and A. Bly. 1995-2000. South Dakota State University. Reported by J. Bauder, Montana State, Agronomy Note 290, 2001.

These data are all very similar in that they consistently suggest that 30 lb N as 28% diluted and sprayed in the cool of the day to minimize leaf burn will provide about ½% protein increase. Growers will need to determine the cost of fertilizer and application, and compare that with the expected returns of ½ % greater protein in either reducing possible protein dockage at the point of sale or a possible protein premium for levels above 14% at harvest.