The value of prairie and grazing brome grasses in pasture mixes

Aaron Kemp, AusWest Seeds, New England & Mid North Coast NSW

The value of adding prairie or brome grasses to pasture mixes in the higher rainfall zones has often been understated, or forgotten. In a pasture mix with other temperate grass species they have the ability to provide excellent quality feed during the shoulder periods when other species are either slowing down due to heat and/or going reproductive. This helps to plateau out the feed curve of the overall pasture mix and improve the feed quality of the pasture sward. In high rainfall or irrigated situations, pastures based on prairie grass can be used as an alternative to ryegrass, and has at times been colloquially known as ‘perennial oats’. Under lower rainfall, pastures based on grazing bromes make good alternatives for perennial ryegrass for sheep without ryegrass staggers issues.

Prairie and grazing brome grasses are both closely related members of the Bromus genus. Prairies and bromes have some excellent characteristics that make them valuable additions to pasture mixes. Both have no known health issues for any class of livestock (no staggers), have excellent feed quality, are palatable and heat tolerant. Prairie grasses and bromes are best suited to the higher rainfall zones (around 600mm +) with some summer rain or irrigation needed to maximise summer production and adult plant survival. Prairie grasses and bromes are short lived perennial plants, usually 2-3 years, but are prolific seeders, with well managed stands having strong numbers of seedling recruitment each year.
Atom prairie grass | AusWest & Stephen Pasture Seeds
Atom prairie grass

While prairie and grazing brome grasses are more similar than they are different, there are some key differences between species and varieties. Prairie grasses have a higher yield potential than grazing bromes, but do need higher fertility and more rainfall or irrigation. Grazing bromes, while lacking in the top end yield potential, will tolerate lower fertility soils and persist in zones with lower annual rainfall and tolerate set stocking better than prairie grass. Table 2 summarises some of the main differences already mentioned to some key prairie and brome grass varieties.

Table 2: Characteristics of key prairie and brome grass varieties.

Variety Min. Rainfall (mm) Sowing rate (mixes) Sowing rate (straight)  Comments
 Atom prairie grass 850+ or irrigation  5-30kg/ha 30-50kg/ha Tiller dense, Year round production, Well drained soils, Rotational grazing preferred
Gala grazing brome 600+ 5-20kg/ha 25kg/ha Winter active, slightly acidic well drained soils
Exceltas coloured brome 650+ 5-20kg/ha 25kg/ha Less winter activity, slightly acidic well drained soils

There is some variation in the sowing rates of both species in mixes listed in Table 2. The actual amount of prairie or brome grass needed in a specific pasture mix will vary depending upon a number of important factors, including:

  • What class of livestock it is for
  • Where the mix is going (local environment)
  • Intended grazing management
  • Other pasture species in the mix

In general, rates of 5–10 kg of prairie or brome grass is adequate for mixes that contain other grass species such as cocksfoot, ryegrass or tall fescue. Higher rates are used where prairie or brome are the sole grass in a mix, combined with clovers and herbs. For specific recommendations on what rate to use talk to your local agronomist, AusWest Seeds or Stephen Pasture Seeds representative.

References:
Agricom; Agrinote; Ceres Atom Prairie Grass; www.agricom.com.au
Hackney B, Harris C, Dear B; (2007); Perennial brome grasses, NSW DPI Primefacts. Primefact No. 383

Prairie grasses have a wide leaf which is high quality and palatable to all grazing livestock. Brome grasses have a somewhat narrower leaf, but still of high quality and stock acceptance. Both plants have an erect growth habit making them friendly to companion species such as legumes, herbs and other grasses.  They produce high quality feed that is comparable to ryegrass, but with greater heat tolerance. Unlike most grass species, feed quality is maintained when the plants go reproductive during spring / summer. In pasture mixes prairie grasses and bromes improve the amount and quality of feed on offer during periods when other species are reproductive and/or struggling with heat.  Outside of the tropics and sub-tropical areas, prairie grasses and bromes do lack the winter growth of ryegrass, but respond well to gibberellic acid. Winter growth can be enhanced to give similar winter yields to ryegrass under favourable conditions with the use of gibberellic acid and nitrogen fertiliser. Table 1  shows the relative drymatter production of common prairie and brome grass varieties relative to a common perennial ryegrass. Across all three sites in this study the prairie grasses were close to or better than the yield of the perennial ryegrass. The grazing bromes were a little more varied, without the top end yield of the prairie grasses.

  Holbrook Bookam Burranga
Average annual rainfall (mm) 600 620 750
pH 4.2 4.7 4.3
Exchangeable aluminium (%) 5 5 25
 Variety Herbage Production (t/ha)
Matua Prairie 13.8  3.3  
Atom Prairie 15.7 3.3 10.8
Bareno Brome 11.2 2.5 2.9
Gala Brome 13.5 2.6 7.3
Exceltas Brome 8.7 1.6 7.2
Kangaroo Valley (Perennial ryegrass) 5.5 3.8 9.3
Table 1: Cumulative herbage production (t DM/ha) of several Brome and Praire grass species grown over 18 months in southern NSW 2005-2006. Taken from NSW DPI Primefact no.383 (Hackney et. al. 2007)

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