Wheat is greening up and starting to grow, which means that spring nitrogen can be applied as soon as field conditions permit. Research has shown no yield reduction as long as nitrogen is applied before Feekes growth stage 7, which is two visible nodes. This week Ed Lentz, Extension Educator in Hancock County, along with OSU Extension specialists Laura Lindsey and Steve Culman, offer the following considerations for nitrogen fertilization of wheat.
Ohio State University recommends the Tri-State guide for N rates in wheat. For now, this system relies on yield potential (which may change in a few years with the update of the Tri-State Guide). A producer can greatly increase or reduce the N rate by changing the value for yield potential. Thus, a realistic yield potential is needed to determine the optimum N rate. To select a realistic yield potential, look at wheat yields from the past five years. Throw out the highest and lowest wheat yield, and average the remaining three wheat yields. This three-year average should reflect the realistic yield potential.
Table 10 in the Tri State guide (https://agcrops.osu.edu/sites/agcrops/files/publication-files/Tri-State.pdf) recommends 110-pound N for yield goals of 90+; 70-pound for 75 bushels; and 40-pound N for 50 bushel yield goal (these recommendations are for total N and include any fall N). If you prefer to be more specific, the following equation may be used for mineral soils, which have both 1 percent to 5 percent organic matter and adequate drainage:
N rate = 40 + [1.75 x (yield potential 50)]
No credit is given for previous soybean or cover crops, since it is not known if that organic N source will be released soon enough for the wheat crop. The Tri-state recommends that you subtract from the total (spring N) any fall applied N up to 20 pound/A, whether you deduct fall N depends how much risk you are willing to take and your anticipated return of investment from additional N. Based on the equation above and deducting 20 pounds from a fall application, a spring application of 110 pounds N per acre would be recommended for a yield potential of 100 bu.; 90 for 90 bu. potential; 70 for an 80 bu. potential; and 40 pounds N per acre for a 60 bu. potential. Nitrogen rate studies at the Northwest Agricultural Research Station have shown the optimum rate varies depending on the year. However, averaged over years, yield data from these studies correspond well with the recommendation equation given above. These studies have also shown that regardless of the year, yields did not increase above a spring rate of 120 pounds N per acre.
Wheat generally does not benefit from a nitrification inhibitor since temperatures are relatively cool at application time and the application is made to a growing crop. This is especially true as the crop approaches Feekes GS 6. However, urea may benefit from a urease inhibitor (products containing NBPT) if conditions for volatilization exist for several days after application. These conditions would include an extended dry period with warm drying temperatures (risk increases with temperatures above 70°F) and evaporating winds. Urea applications need at least a half-inch rain within 48 hours to minimize volatilization losses unless temperatures remain relatively cool. The urease inhibitor will prevent volatilization for 10-14 days with the anticipation of a significant rainfall event during this time.
Certified Weed Free Forage/Mulch Program
Rover pipeline construction has started here in Wayne County, and there are a number of other pipelines that will cut across Wayne County in the future. One of the pipeline construction needs is a source of certified noxious weed free forage and mulch as a cover on the new seeding that is made as construction is terminating. Certification for this type of mulch/forage is through the Ohio Seed Improvement Association, and according to the OSIA, there are only four certified noxious weed-free producers in Ohio and none are located in Northeastern Ohio. This may be an income opportunity to sell to pipelines.
OSU Extension Stark County with support from Ohio Farm Bureau is hosting a lunchtime program about becoming a certified noxious weed-free forage/mulch producer on Wednesday, April 12, at the R.G. Drage Career Center, 2800 Richville Drive SW in Massillon. This certification is needed to sell forage/mulch to the pipeline companies and certified producers are often sought by landscapers and site restoration companies. A representative of the OSIA will present the program and be on hand to answer questions.
Registration/sign-in for the program starts at 11:15 a.m., followed by lunch at 11:30 a.m. Thanks to support from Stark County Farm Bureau, the cost of lunch is only $5 per person. The program will start at 12:15 p.m. and should last about an hour. RSVP to Heather Neikirk by email at firstname.lastname@example.org or by phone at 330-832-9856, ext. 3476.
Rory Lewandowski is an OSU Extension Agriculture & Natural Resources educator and may be reached at 330-264-8722.