Thursday, June 3, 2010

Fill Your Probe For PSNT

The rain from yesterday kept us out of the field for most of the day, but we able to get back to sidedressing corn on some of our lighter ground in the afternoon. The corn is really growing fast and we are anxious to get the sidedressed N applied. We have one experiment where we will perform the PSNT, or Pre Sidedress Nitrate Test. This is where a soil sample is collected from a field several days prior to sidedress application for determination of nitrate nitrogen content by a lab. Then a recommendation is made with consideration of the nitrogen already there. In some years with heavy rain, nitrogen may be lost, and this test will tell you how much. Alternatively, there may be accelerated mineralization of plant-available nitrogen if conditions were warm (but not hot) and good (but not excessive) moisture. So this test is recommended in order apply the right amount of nitrogen, and avoid the consequenses of over or under application.Here we see Stephanie collecting PSNT soil samples. The recommendation is for 12" cores, so you have to have a proper probe. Also, avoid sampling the planter-fertilizer band. If you have applied much nitrogen at planting, then subtract that from the recommendation. We took our sample by the extension office this afternoon, and should have the results by e-mail by Monday or Tuesday. In this experiment, we will follow the PSNT recommendation with several different nitrogen fertilizer formulations, plus compare it to what would be our standard recommendation. I will admit that in past testing both at the NCRS and in field trials in Iowa, the PSNT has not been as effective as our standard recommendations. It seems that the PSNT recommendation was too low, and it showed at harvest. But that was a few years ago, and we decided to give it another shot on one of our new farms. The hard part was selecting a yield goal, as we have never grown corn on this farm before. I just hope we can make some good headway on our sidedress before forecasted rains come again. Stay tuned.