Use a Sound Corn Nitrogen Strategy to Combat Rainy Weather

Abundant spring rainfall can create havoc with nitrogen management by delaying fertilizer application and also promote massive nitrogen loss. Rainfall has been relentless and frequent this season, likely restricting opportunity to side-dress, if you were lucky enough to plant thus far. Therefore, you may need to consider making an unplanned aerial application of granular fertilizer to temporarily supply crop needs, until soils dry enough to permit side-dressing, if there is little or no nitrogen available for your young crop.

Although corn doesn’t require much nitrogen during seedling stages, you need to supply some nitrogen by the time it gets 4 to 6 inches tall or slightly taller if you applied a starter fertilizer. Corn nitrogen needs are less than 10% of seasonal demand until the plants are about 12 to 18 inches tall (V5-6), so 30 to 60 lbs/a of N per acre should comfortably support the crop until side-dress.

Rainy conditions like those experienced thus far this spring can promote significant nitrogen loss and justify why we strongly advocate “spoon feeding” your corn crop using a split application strategy. The effectiveness of this method depends heavily on the amount fertilizer applied at various times relative to crop need, especially in wet years. The strategy reduces the amount of nitrogen exposed to wet conditions, particularly during the spring, so more nitrogen will be available throughout the season and at key crop growth stages to optimize productivity. The key stage for your second nitrogen application (or side-dress) is when rapid nitrogen uptake begins when plants are about 12 to 18 inches tall (V5-6) – this is known as the beginning of the rapid growth stages. A pre-tassel application can also be incorporated as simply another split in this system to further reduce early-season nitrogen exposure and maintain nitrogen availability until the end of the season, when deficiency is most likely.