The first results from a project to sample soil this fall to see how the dry growing season and low corn yields affected nitrogen levels are now available.
One of the reasons for conducting the study was to see how much nitrogen is in the soil now to estimate the likely nitrogen loss over the winter and early spring.
"November was relatively dry in Illinois, and there have been few reports of tile lines running," says Emerson Nafziger, University of Illinois crop sciences professor. "Now that soils have cooled down, the nitrogen, mostly in the form of nitrate, that is in fields most likely will stay in the soil until and unless tile lines run, when we can expect some of it to exit in tile drainage water."
Soil Sample Project Finds A Lot Of Leftover N Still In The Field
The second reason was to estimate how much nitrogen is available to next year's crop, especially if corn is planted in the same fields.
"It's typical for some loss to take place if we have normal precipitation from fall to early spring, but if this winter is dry, some of the nitrogen there now should be available for next year's crop," Nafziger explains. "We can't know how much will be there in the spring without taking soil samples at that time, preferably close to planting."
Many people volunteered to take samples. Participants were asked to take 0- to 1-foot and 1- to 2-foot samples at a single site. Site information, including how much nitrogen had been applied in 2012 and what the yield was, was sent with the samples, which were tested for both nitrate and ammonium. About 130 sites have been sampled to date in the U of I part of this project.