Slow Release Preplant N for Winter Wheat

Preplant N for early planted winter wheat is frequently less effective than spring topdressed N.  While the mechanism is not always clear, spring topdressed urea N has been more effective in 8 of 11 trials.  In addition, the current NRCS 590 Nutrient Management Standard discourages fall preplant applied N.  Several mechanisms that would explain the results have to do with excessive readily available N during early vegetative growth stages.  Consequently, slowing the N release may improve preplant N effectiveness.  Polymer coated urea (PCU) may have potential for slowing fall preplant N release.  A study was conducted at the Parma R & E Center in the 2005-06, and 2006-2007 seasons to compare fall preplant PCU with fall preplant urea for soft white winter wheat.  The results for this study are available at the links below.

Slow Release N Source and Timing Evaluation for Irrigated Winter Wheat,  Research Progress Report - 2006

Slow Release N Source and Timing Evaluation for Irrigated Winter Wheat,  Research Progress Report - 2007