Nitrogen Timing Study

2017 Southern Illinois Wheat Nitrogen Timing Study - Urea

  • Southern IL

The purpose of this study is to evaluate various timings of nitrogen (N) applications, in the form of urea, to determine their effect on N use efficiency, yield and profitability.


Much like the UAN timing study, the urea N timing study has a slightly different spin than in years past. Similar to UAN, urea has shown the best economic gains in past years with UAN timing study. This year, the three split applications showed the highest yield and return. Even when considering an additional application cost, the third application of N provided a positive net return in this trial.



Urea is a NH4+ forming compound that does not contain NO3-. UAN consists of 50% urea, 25% NH4+, and 25% NO3-. When we look at the N cycle, we typically think of NO3- as being the most readily taken up form, followed by NH4+. Loss of N through ammonia volatilization (lost in a gaseous form) can occur when applying urea or UAN. When making UAN applications, N loss can occur in the form of NO3- leaching if followed by a heavy rain with denitrification.






Planted 10/8/2016 | Harvested 6/13/2017 | Population 1,500,000 Seeds/A. | Row Width 15 in. | Previous
Corn | Tillage No-Till | Herbicides 2 oz. PowerFlex® HL, 0.75 oz. Harmony® Extra SG | Insecticides Escalate, 1.28 oz. Warrior II | Brand 125 | Soil Type Cisne & Bluford (silt loams) | Soil Test Values pH 6.9, O.M.% 1.7, CEC 5.6 | Percent Base Saturation Ca 76.1, Mg 19.4, K 3.0, H 1.5 | Parts per Million P 24, K 66, S 4, Zn 3.8 Mn 61, B 0.2