This year, corn planting was delayed due to an unseasonably cold spring, and at this time corn growth stage ranges mostly from the V2 to V6 across the state. Many producers had doubts concerning preplant nitrogen (N) application due to high N fertilizer prices, and now some are wondering about possible in-season diagnostic tools to assess a potential need for supplemental in-season N application.
Sampling corn stalks this fall will likely be later than normal due to the delayed planting in many Iowa cornfields. The overall suggestion is to wait until crop maturity, and sample within 1-3 weeks after kernel black layer. This does not work well for silage corn, so the suggestion is to collect stalk samples at the time of silage harvest or within 24 hours after harvest (as long as no rain between harvest and sampling).
Winter seems to be never ending, and spring not arriving. This could lead to a compressed period for field work before corn planting begins. There are conversations underway about switching planned spring preplant anhydrous ammonia to another nitrogen (N) product like urea-ammonium nitrate solution (28 or 32% UAN) or granulated urea. And likely discussions about changing from preplant to sidedress applications. What should be considered?
The dry conditions in some areas of Iowa in 2017 have raised several soil fertility questions. In some cases, there has been relatively normal crop production and no need for management changes. In other situations with severely damaged crops, there is potential for adjustments for the 2018 corn crop.
By Mark S. Johnson, Kelvin Leibold and Paul Kassel, ISU Extension and Outreach
