June 14, 2001

Wet Weather Has Some Growers Looking At Nitrogen Application Alternatives

"Most producers have their nitrogen on before they plant, but this has been a very strange year from start to finish," says Dave Franzen, North Dakota State University Extension Service soil science specialist. "Last year many growers didn’t get nitrogen on because it was too wet and the season too short. This year we’ve had a very wet spring."

Many growers are now considering top dressing. "Growers are used to side dressing corn and sunflowers when there are rows at 22 inches or wider. But if rows are narrower then there’s a problem getting knives and tillage tools into the ground. In some cases, your only alternative is to lay the material on top."

Some may consider using a dry material such as urea. However, soils are warm this time of year and within a couple of days the nitrogen starts to dissipate in the air as enzymes break the urea down to free ammonia. Franzen says producers can lose a major portion of their nitrogen within a week or two.

Using liquid fertilizer also has its problems. "Half or most of the liquid nitrogen used (usually 28% N solutions) is urea. So they still face the problem of the product dissipating in air, " says Franzen.

Spreading nitrogen in liquid form may also burn some of the plants. Small grain growers with crops in the two to three leaf stage may want to consider using 50 pounds of nitrogen mixed half and half with water. "You can really burn some crops if you apply 60 to 90 pounds of nitrogen," says Franzen. "The application should be made evenings, when there’s dew on the ground, after it’s rained or if it’s going to rain in a short period of time."

Growers that are planning on using liquid fertilizer should consider an alternative to using nozzles according to Franzen. "I would recommend using a straight stream orifice which are little disks with holes in it that are calibrated a certain amount of liquid at a certain speed. They are made out of stainless steel so they will last a long time. The sprayer should be set using 10- to 15-inch spacings and set to spray at an angle. That way if the sprayer is directly above a row it won’t burn the plants. There will be some burning but it won’t be as devastating compared to broadcasting the nitrogen over the entire field."

Franzen says Mother Nature can also help with the volatility issue. Rain within 48 hours will help break down the urea. However, at least a quarter inch of rain is needed.

Another alternative to the volatility issue, especially those in a no-till situation with heavy thatch cover, is to add Agrotain. It keeps soil enzymes from breaking down the urea for about ten days. "Hopefully within that 10 day period they’ll get substantial rain," says Franzen. "That will move the nitrogen down to the roots where it belongs. Without Agrotain you get about two days. Then producers need to think about rotary hoeing or heavy cultivation. Agrotain was widely tested by universities before it was released and works well."

Soil testing is a tool that should be considered if there is sufficient time between sampling and the application window. However, Franzen says the numbers mean a little different recommendation than a fall or pre-plant sampling. This time of year there are no "previous crop credit" allowances, as most of these would be accounted for in the spring test. Also, a growing crop has already taken up some nitrogen, so a more conservative recommendation is usually warranted.

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Source: Dave Franzen, (701) 231-8884, dfranzen@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, Richard_Mattern@ndsu.nodak.edu

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