NDSU Extension - Ramsey County

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August 13, 2012 Agriculture Column

Howdy!!!

The fall season is moving right along, unfortunately we are having some issues with rain delays but hopefully we can get back into the full swing of things real soon.  There were rain amounts all over a wide range again with this last system to include amounts from .20 inches to around 2 inches.  The yields of small grains has been remarkable considering the early season dryness we experienced but time will tell about the whole crop and how well we did.     Because the harvest has been much earlier than past years some will likely think about an earlier application of Nitrogen.  Below is a article wrote by Dave Franzen explaining the complications of an early application of nitrogen.

Fall Nitrogen Application

Although fall‐applied fields often suffered more loss than spring‐applied fields, it is not always the case. Growers that applied late in the fall when our recommendations would suggest it was safer are more satisfied with their results than those that were early. For those who cannot recall our recommendations for fall nitrogen timing, here they are again.

1. Do not fall apply N on soils that typically flood in the spring or to soils with sandy loam or coarser textures.

2. Do not even think about applying anhydrous ammonia until October 1.

3. After October 1, check the soil temperature measured at 4 inch depth from 6‐8AM. When it hits 50 F, it is practical to apply anhydrous ammonia (but not urea!)

4. A week after the date for anhydrous ammonia, growers can start applying banded urea.

5. 2 weeks after the date for anhydrous ammonia, growers can start broadcast‐incorporating urea.

 

This past season, the date the soil temperature dropped to 50 F was about October 15. That means that banded urea application should not have begun until October 22 and broadcast urea until October 29. There is nothing wrong with well‐timed fall N application in North Dakota. In years of dry weather, it didn‟t matter when nitrogen was applied. If the last 18 years of wetness is an indication of the beginning of a trend, we think that this winter and spring will also be wet and we will be set up for losses for N that was applied too early. Agronomy does not always mesh with convenience. Although many growers have a „harvest gap‟ in September after small grain harvest and before soybeans/corn/sunflower, it is not the time to fall apply N. P and K can be applied during this time, but not N. Too many bad things can happen to

early applied N if it is applied too early with too much fall ahead of it. A nitrification inhibitor should be used not to move the date of application earlier, but to protect the N‐applied at a safer date from unanticipated losses from early spring wetness. N‐Serve™ can be applied with anhydrous ammonia to protect N from losses due to nitrification in the fall/spring. Instinct™ is an encapsulated form of nitrapyrin (active ingredient in N‐Serve), and the label we have currently lists it as a spring additive with urea or UAN. Check with your Dow‐ Agro Sciences rep to see if it is labeled for fall application with urea. In the spring, products with the additive DCD (examples are Super‐U™ by Agrotain, Int., or Guardian™ by Conklin) will also slow nitrification. One product that is sold as a nitrification inhibitor, but does not function like one is Nutrisphere™. It is neither a nitrification inhibitor nor a urease inhibitor and should not be used as one.

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