By Randy Simonson, Ph.D.
Technical Services Manager
Nitrogen loss in the corn could be a big problem this year. With all the rain many of us
have received, pre-plant nitrogen may have either leached (in lighter soils) or been lost
through denitrification (in heavy soils). Several years ago I had this problem on the
research farm. I had broadcasted urea on the corn ground and then immediately incorporated
it before planting. We received a lot of rain that spring and there was a small area in
the back of plots where the corn turned yellow from nitrogen deficiency. This is when I switched
to sidedressing all the nitrogen on the corn.
A nitrogen deficiency may show up at any time depending upon how much nitrogen was lost. The
best way to determine how much nitrogen is left is to take a one-foot soil sample and send it
to a soil lab to have it tested for nitrates. You may want to buy a small handheld nitrate
meter so you can test the soil right there in the field and find out very quickly whether there
is enough nitrogen. One of these units cost about $360.00. The key to taking a
nitrate test is to take many cores. This is not as critical when nitrogen was broadcasted,
but it is very crucial if the nitrogen was banded.
You may find that some corn fields have lost some nitrogen and even though they have enough
nitrogen now, they may not have enough nitrogen to get them through the season.
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