June 22, 2011
Heavy Rains in Midwest Will Likely Result in Nitrogen Losses
There are concerns that the recent heavy rains are going to result in the loss of some of the nitrogen that has been applied to the corn crop. This was a concern last year and it could well be an issue again this growing season. The soil does not have to be flooded in order for the nitrogen to be lost. Extended periods of saturated conditions can cause the nitrogen to be lost as well.
If some of the nitrogen has been lost, it will start to show up as dry leaves appearing at the base of the plant. When a corn plant starts to fill the kernels it transfers nutrients from the lower leaves and stalk into the kernels. The upper leaves remain green as long as possible in order to continue conducting photosynthesis. If the plant has produced enough nutrients during the growing season, this translocation occurs as the plant matures. If the plant did not produce enough nutrients due to a lack of nitrogen, the translocation process begins early and well before the plant starts to mature.
In the areas where some of the nitrogen may have been lost, the lower leaves start to turn brown in late July or early August. If this occurs, it may be an early indication that indeed some of the nitrogen has been lost and the resulting corn yield could be disappointing. That is what occurred in 2010 in parts of the eastern Corn Belt.