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Fertilizing Forage Grasses for Seed Production 2010-2012

Ray McVicar
Executive Director
Saskatchewan Forage Seed Development Commission

The project was supported by the Agricultural Demonstration of Practices and Technologies (ADOPT) initiative under the Canada-Saskatchewan Growing Forward bi-lateral agreement.

The objective of this project was to compare the benefits of using coated fertilizer products to non-coated products on forage grasses grown for seed and to demonstrate if field scale coated fertilizers will increase yields when applied directly after harvest.
Nitrogen fertilizer increases seed yield of perennial grasses by increasing the number of seed-forming tillers.  Timing of nitrogen application is important because many perennial grasses need nitrogen to ensure there are a number of well developed tillers present prior to induction of flowering tillers which can occur in the fall.
Ammonium nitrate is not commercially available so growers are mainly using Urea (46-0-0) which is prone to volatilization, especially if applied in early fall when air and soil temperatures are higher.  Agrotain, a nitrogen stabilizer, helps reduce vitalization by slowing the conversion of Urea to ammonium.

Materials and Methods
Two field experiments were established to investigate the effects of Agrotain on hybrid bromegrass and timothy seed yield and quality.  Due to extremely wet field conditions in the Carrot River area in the autumn of 2010, three additional planned sites were not established.

Agrotain and Urea were applied to Success hybrid bromegrass (seeded in 2009) on October 4, 2010 at a rate of 196 lbs/acre (90 lbs/acre of N) on 7 acre plots near Carrot River, SK.  Treatments were applied to Comtal timothy (seeded in 2011) on October 13, 2011 at a rate of 180 lbs/acre (82.8 lbs/acre of N) on 6 acre plots near Carrot River, SK.
The number of flowering tillers per meter square was determined prior to swathing.  Ten hybrid bromegrass stems were taken prior to swathing and were examined to determine the percentage of florets that developed normally.  The centre portion of each plot was swathed, harvested and weighed using a weigh wagon to determine gross seed yield each year.  A seed sub-sample of each treatment was taken to determine seed dockage, seed size, and germination.

Results and Discussion
It is very important to note that this is a demonstration trial, statistical analysis was not carried out and differences may or may not be significant.

Agrotain and Urea increased the number of flowering tillers and seed yield of hybrid bromegrass compared to the unfertilized check (Table 1).  Weed seed contamination of hybrid bromegrass seed was reduced when Agrotain and Urea were applied presumably due to increased competition from the grass (Table 2).  Hybrid bromegrass seed size was reduced compared to the unfertilized check when Agrotain and Urea were applied (Table 2).  Perennial grasses have the ability to compensate for a reduction in flowering tillers by increasing seed size and seed number per tiller (Meijer and Vreeke 1988b).  This may explain why seed size increased when the number of flowering tillers decreased in the no nitrogen treatment.  Hybrid bromegass and timothy had the highest seed yield and germination rate when Agrotain was used compared to Urea (Tables 1-3).

Thank you to Saskatchewan Agriculture.  Thank you to James Silcox (Pasquia Agro, Carrot River, SK) and Clayton Myhre (PICKSEED,  Nipawin, SK) for technical support and Dr. Fran Walley (U of S Saskatoon, SK) for reviewing the annual report.  Without the support of the Saskatchewan Forage Seed Development Commission and grower co-operators like Bruce Bartel and Dave Maxwell (Carrot River, SK) projects like this would not be possible.

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