a. You may be able to see the N being leached through the soil with the EC graphs. I’ve noticed several fields with course texture soils with significant increase trends in the lower (20 & 36”) sensors. Certainly, some of these ions are Nitrate, which means we have pushed some of our N below our effective root zone.
b. In addition to leaching, saturated soil loses N through denitrification. This loss increases as the soil warms. At this time of the year, most of our applied nitrogen is in nitrate form, and subject to loss. Illinois University reported a 4-5% loss of nitrate-N from denitrification per day of soil saturation. When they maintained saturation for 6 days their study found a 60 to 70 lb N/acre loss on finer texture soils. An application of 50 lbs additional N prevented yield losses. However in sandy soils because of significant leaching 50 lbs wasn’t enough to fix the problem.
c. University of Nebraska studies estimated denitrification losses of 10% when saturated for 5 days and 25% with 10 days of saturation. That was on soils with temperatures of less than 60 degrees. The warm soils we have in mid-June would be more.
Here is an actual example of how a sensor might help us understand what may be happening to our N in our wet fields. Watch for these things and mention them to your customers.
Is additional N going to be necessary to maintain yields?
Can you help your growers with a Fertigation prescription?