Large Urea Granules for Broadcast Application for No-till Cropping in Alberta Spring Wheat

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) (Nyborg and Malhi 1979, and Goos and Johnson 1993). 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).


Justification

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) (Nyborg and Malhi 1979, and Goos and Johnson 1993). 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). The earlier research noted above was done largely by hand application to small field research plots. Standard spin-broadcast application equipment available earlier could not achieve an even spread of the larger urea granules. More recent pneumatic floater spreaders do have the capability to handle the larger granules and achieve an even spread of granules over the spreading width of the equipment. Goos and Johnson’s research investigated the addition of a nitrification inhibitor (DCD) with the urea in different sized granules; such treated granules were not commercially available at the time of this research. 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.


Objectives

Potential Benefits to the Ag Industry

• This would allow a low cost, low energy input method of applying N to no-till cropped fields in the NGP.
• Significant areas of the NGP now apply broadcast applications of regular sized urea in the fall or in the spring prior to planting. Under conditions conducive to ammonia volatilization, N losses have been measured for fall and spring surface broadcast applications of urea (Engel 2008, and Engel 2009).
• There is potential to allow farmers to apply N in the fall at a time when urea N prices are usually less compared to spring prices, and spread out their work load by applying N in the fall and having less fertilizer to handle just before or at planting in the spring.
• This technology (fall broadcast applications of large granule urea treated with a urease and nitrification inhibitor) can be used in both fall and spring no-till planted wheat and barley, and spring planted canola cropping systems.

If this initial research shows an advantage for the large granule urea treated with urease and nitrification inhibitors this research will be continued at multiple locations in Montana, North Dakota, Saskatchewan, and Manitoba for further evaluations and generation of research data under different agro-ecological zones.


Methodology

Experimental Factors
Timing (2): Fall compared Spring applications
Urea Granule Size (2): regular 3mm and large 10 mm size urea granules
Inhibitor Additions ( 3): regular untreated urea, urea treated with Agrotain, and urea treated with Agrotain plus a nitrification inhibitor (DCD)

Experimental Design
The study will be a four replicate, factorial design, with the inclusion of a no-N control treatment, and a standard farmer practice of side-banding at planting treatment for comparison purposes. The last two treatments will not part of the factorial design and statistical analysis, but are included to assess N response and how the technologies being evaluated compare to standard farm N applications for south-east Alberta.