Nitrogen Fertilization Methods for No-till Cropping of Winter Wheat in Central Montana

Earlier research in Alberta and North Dakota showed that using larger granules of urea compared to regular sized ag-grade urea was a means of increasing crop yield and reducing the potential for denitrification losses by slowing down nitrification of urea nitrogen (N). It is thought that a larger granule urea (up to 10 mm in diameter) that is used in helicopter applications to forestry replanting stands, and in agro-forestry plantations could be used as a broadcast application in no-till cropping systems in the Northern Great Plains (NGP). Recent developments of technology now allow the treatment of different sized granules of urea with both a urease and a nitrification inhibitor (i.e. Agrotain and DCD). This study will investigate the following factors in a factorial field experiment.


03 Mar 2012

2011 Annual Interpretive Summary

The most common method of applying N fertilizer to winter wheat crops in central Montana, is to broadcast urea or dribble apply liquid urea ammonium nitrate in the late fall, or early spring. With shallow soil profiles in central Montana, the soils do not hold much precipitation over winter. When precipitation exceeds the soil water holding capacity, the excess water carries N out of the soil profile, causing ground water contamination.

A study was started in the fall of 2010 to compare other possible methods of applying N fertilizer to winter wheat crops, that may reduce the risk of leaching or denitrification losses of applied N fertilizer. Other possible methods include side-banding urea during the planting operation of wheat in mid to late September, placement of ESN® or controlled-release polymer coated urea in the seed-row of wheat at planting, or application of urea treated with urease and nitrification inhibitors in the mid-fall or early spring. In this experiment the winter wheat was planted in mid-September 2010, the two at-planting treatments described above were applied at this time. The fall broadcast treatments were applied on October 5, 2011, and the spring broadcast treatments on March 24, 2012. Treatments included: urea broadcast in mid fall (Urea BF), urea broadcast in early spring (Urea BS), Super Urea® broadcast in mid fall (SUreaBF), Super Urea broadcast in early spring (SUBS), ESN applied in the seed-row at planting in the fall (ESNWSF), regular urea applied in the seed-row at planting in the fall (UreaWSF), and check (no N applied).

Winter wheat grain yield was significantly affected by N source, application timing, and application method. Generally, spring application had greater yields than fall application. In this initial study Super U (containing both a urease and nitrification inhibitor) did not result in a greater yield compared to regular urea whether applied in the fall or spring. The mid-row banded application did not result in a greater yield than the broadcast application in the fall. This study will be continued for two more growing seasons. MT-18