Warm Season Grass Demonstration Plots

Ducks Unlimited, University of Guelph


Glen Osprey Farm


Project Goal: To Introduce warm season native grasses to the agricultural community.

Objective: To assess the potential use of warm season grasses as summer pasture and waterfowl nesting habitat.


Ducks Unlimited - Calvin Holden, Nick Kinkel and Owen Steele

University of Guelph - Dr. Jock Buchanan-Smith and Sharon Howard

Glen Osprey Farm -David and Nancy Pease

Plot Info:

The total area of 6.2 acres was divided into three plots

(1) Seeded to Switch grass (Panicum virgatum)

(2) Seeded to Big Bluestem (Andropogon gerardii)

(3) Seeded to a mixture of Switch Grass, Big and Little Bluestem and Indian Grass


Soil Fertility:

High Land: P=4 L, K=53 L, pH=7.2, Mg=193 H

Low land: P=3 L, K=43 L, pH=7.5, Mg=358 H


Planting and field preparation

On September 16, 1997 the field was sprayed with 2L/Ha of Roundup. A further application of 3L/Ha was done on May 13, 1998.


No-Till Drill from Ducks Unlimited

Owen Steele(pickup), Calvin Holden and Nick Kinkle by drill


No-Till planting on May 26, 1998 - No fertilizer was applied

Switch Grass Plot on July 12, 1998

1999 Production

Because of the continued presence of other grasses and dandelions, the plots were resprayed in early May with Roundup/2,4-D. This did not seem to affect the warm season grasses as they were still dormant. It is also interesting to note that many of the trefoil plants also survived. Unfortunately, this also applied to the Canada thistle.


Switch grass taken July 5, 1999


Big Bluestem plot and mixed grasses plot

July 5, 1999

 Sharon Howard, University of Guelph, taking grass samples, July 19, 1999

 Big Bluestem plot just prior to grazing, July 23, 1999

The following summarizes the data U of G has prepared to date:





 Yield (T/Ha)

















The mixed grass plot of switch and bluestem. Note how green the warm season grasses are when compared to the mature timothy and orchard in the background.

29 cow calf pairs + a bull grazing 2 acre switch plot, July 19- 23, 1999




Switch grass after grazing. Most of the large plants in the background are thistles.

Cattle grazing Big Bluestem plots July 23 - 27, 1999



Aftermath of grazing big Bluestem pasture.

The cow herd pastured on the 6 acre demonstration plot from July 19 until August 1, a total of 13 days.

September 18, 1999

All three plots were clipped with a claas disc mower after pasturing .

On August 16, 1999 the plots were sprayed with 2.75L/Ha of Embutox for thistle control.

The above photo shows the regrowth as of mid September. It is important to note that warm season grasses store their winter reserves, not in the root system, but in the top 8 inches of the plant. The low regrowth rate of the Big Bluestem may create winter-kill conditions and low level clipping may not be a good practice for this grass species.


Results for the 2000 year growing season



 Switchgrass early spring 2000

 1st growth of Big Bluestem, year 2000

As seen in the photo above, left, the Switchgrass did provide a reasonable cover, suitable for duck nesting habitat. The green in the photo is black medic, a weed that seemed to persist inspite of the numerous sprayings of these plots. The above photo on the right shows the emergence of the Big Bluestem as the light green grass, again with the presence of black medic. The Big Bluestem failed to produce much regrowth after the clipping in 1999 and it was a worry that this warm season species would not have sufficient reserves to survive the winter and grow again in the spring of 2000. At this stage, in the spring of 2000, it appeared that the Big Bluestem had survived fairly well.

Dry Matter Production Comparison

1999 - 2000

Note: there has been no fertilizer applied to these plots.



 Yield (lb/ac)

 Offtake (lb/ac)

 Residue (lb/ac)

 % utilized

 lb DM /AU/day
 Switchgrass '99

 Switchgrass '00





 Big Bluestem '99

 Big Bluestem '00





 Mixed '99

 Mixed '00






For 2000, there were 43 cow calf pairs plus 1 bull (44AU)compared to 29 +1 in 1999 (30AU)

Switchgrass plot = Cattle in 2:30pm July 24 Cattle out 8:30 am July 27

Big Bluestem plot = Cattle in 8:30 am July 27 Cattle out 8:00pm July 28

Mixed plot = Cattle in 8:00pm July 28 Cattle out 8:30 am July 30

The results in the above table show how dramatically the Big Bluestem production has decreased (56%) from the previous year. One might also conclude, from the relatively high % utilization figures of the Switchgrass, that the increased presence of cool season grasses (mature at the time of grazing) and weeds in the other two plots contributed to the decreased consumption by the cattle. The Switchgrass has maintained a relatively thick stand while the other plots have shown a noticable thinning.

After the mid summer grazing, the warm season grass plots were untouched for the remainder of the growing season in order to encourage the grasses to build up their reserves for the winter.

Cattle Grazing Switchgrass July 24, 2000

Cattle grazing Big Bluestem July 27, 2000


Results for the 2001 year growing season


There were only a few photos taken in 2001 and unfortunately no forage measurements were collected for analysis. 2001 saw a large difference in warm season grass population in the three plots with only a few specimens surviving in the Big Bluestem and the mixed plot. An estimate, by the author, of a 40% to 50% stand of Switchgrass remained in the first paddock in the fall of 2001. In a field immediately adjacent to the warm season grass plots a pasture mixture was sown in 1999 (orchard grass, timothy, alfalfa, trefoil, and ladino). To be fair, the soil and drainage conditions are superior in the pasture mixture field but, taking this into account, there is little doubt in the author's mind that the pasture mixture field surpasses the best of the warm season, switchgrass, production.

There appear to be two major disadvantages for warm season grasses in our location.

The first is related to the requirement for a warm season grass to enter the winter with at least 8 inches of top growth to survivie. The switch grass was able to do this but only if grazing was prohibited after mid August. The other warm season species did not appear to have sufficient regrowth time even if grazing was stopped at the end of July. As a consequence, the warm season plots have only been grazed once each growing season. The adjacent cool season grass field was grazed four times this summer providing many more days of production.

The second disadvantage may be related to the first. All of the paddocks have now been invaded by cool season grasses, clovers, trefoil, and weeds. It appears that the warm season grasses are not able to compete by maintaining a thick sward. This stand reduction may be due to winter kill of specific plants or it may be the result of early spring competion from these invading species that have the ability to far outpace the warm season grasses during the period. Warm season grass seed is not inexpensive. These fields were planted in 1998 with no forage grazed during that year. Production was good in 1999 and 2000 for the switch grass. 2001 warm season grass production appeared to be significantly reduced although no direct measurements were taken. The author would estimate that the best of the warm season grasses, Switchgrass, would only be productive for 4 years in the North Dufferin area of Ontario. When one compares a well managed cool season legume, grass pasture to Switchgrass pasture in this location, the majority of the advantages are with the cool season pasture.