Here’s a recent report from Penn State on late season stalk quality.

The educational video for the late season corn stalk nitrate test can be accessed here.

Nitrogen (N) management is one of the most difficult decisions in corn production because of the many factors that influence N behavior including: materials, timing, weather, etc. This is especially true when manure is part of the system. Standard recommendations try to account for many of these variables and early in—season tests such as the Pre—sidedress Soil Nitrate Test (PSNT) and Chlorophyll Meter test are very helpful in reducing the uncertainty in N recommendations. While we can never totally eliminate this uncertainty, with experience we can minimize it. A key to improving N management over time is having reliable feedback on how well your N management is working. Good yields and dark green plants are certainly good indicators of adequate N but they do not tell us if we have too much N, which can be a problem especially with manure. Also, some visual symptoms of N deficiency late in the season may not always indicate a yield loss.

The Late Season Corn Stalk Nitrate Test has been shown in research at a number of locations, including across PA, to be a reliable end of season indicator of crop N status. It provides a good assessment of whether the crop had the right amount of N or too much N or whether it ran out of gas. This information combined with records of N management can be very useful for making future management decisions.

To do this test, 8—inch long sections of corn stalk (subsequently cut into two inch long segments) are taken starting 6 inches above the ground. Pruning shears usually work well for taking these samples. Stalk sampling can be done anytime between about the ¼ milkline stage of the grain, which is just before silage harvest and up to 3 weeks after the grain forms a blacklayer. If possible, dry the samples immediately or send them to the lab as soon as possible after collection. If there is more than a day between sampling and sending, refrigerate (don’t freeze) the samples until you can send them. Keep the samples in paper (not plastic) bags. While you could test all fields, testing a few representative fields will probably be adequate to provide a good assessment of your N program. Detailed instructions and submission forms can be found here:

This test is available through the Penn State Agricultural Analytical Services Laboratory (AASL). The cost of this test is $10. Additional information is available on the AASL web site Results of this test provide a good assessment of the adequacy of the nitrogen management in a field and can be very helpful in adjusting management in the future.