Creeping bluegrass (Bothriochloa insculpta)is a summer-growing tufted perennial with creeping (stoloniferous) stems that rapidly cover bare ground. Needing more than 550 mm of annual rainfall to persist, it is suited to well-drained loam and clay soils, but will also grow better than most other grasses on difficult to manage forest soils. It is tolerant of dry conditions, but does not tolerate waterlogging or prolonged drought.
Flowering in late autumn, creeping bluegrass produces leafy, good quality feed in summer and autumn, carrying through into early winter until frosted. Although tolerant of fire, burning is usually unnecessary as the dry grass remains palatable.
Hatch was the original commercial variety with bluish-green leaves, with purple coloured stems. Although the crowns send out long runners, they do not readily take root from the nodes to make new plants.
Bisset is a newer variety that has finer, greener-coloured leaves and stems, with reddish colourings. It will establish faster and flowers about two weeks later than Hatch. Its runners are more inclined to take root at the nodes and make new plants. It is more tolerant of frost.
When to sow
Creeping bluegrass may be planted from October to late February. If sowing in early spring be aware that even though evaporation is lower, weed competition at this time can be detrimental to young pasture seedlings. Sowing in mid-summer (January to February) when there is a higher probability of receiving consecutive rain days, has the best chance of success. It is also the most likely period to receive good follow-up rain after planting.
Best results are obtained from a prepared seedbed that has been fallowed for moisture and nitrogen accumulation and for weed control. The surface 50 mm should be fine and firm. The chances of successfully establishing a pasture improve if the sub-soil moisture is good at sowing.
Depending on soil depth aim for a minimum of 40 cm of wet soil under the seedbed. Rougher seedbeds with less soil disturbance need a higher seeding rate and give less reliable results. The ash left after a scrub burn can make a good seedbed.
On sandy surfaced soils, good pastures have resulted from broadcasting seed into standing winter cereal stubble (e.g. oats) followed by grazing. The animals cover the seed by trampling it into the soil surface.
Sow 2-3 kg/ha of good quality seed.
A good stand of creeping bluegrass is highly competitive but lucerne (1-2 kg/ha) and barrel medics (2-4 kg/ha) have been successfully undersown with the grass on the Darling Downs.
Sowing method and sowing depth
Seed may be broadcast onto the dry seedbed surface, or drilled into the dry seedbed with precision planters. The small seed should be within the first 5-10 mm of the soil surface.
Seed soil contact may be improved on non-crusting soils by rollers or presswheels that will firm the soil around the seed. Be careful if harrowing after sowing that the small pasture seed is not being buried by more than 10 mm of soil or the shoot might not have the energy to emerge.
Creeping bluegrass seed is light and fluffy and getting the seed to flow at a steady rate through planting equipment can be a problem. New seed boxes with better seed handling mechanisms or pelleting are methods of improving seed flow. Mixing seed with superphosphate, or sawdust, will allow it to be planted through the fertiliser box of a combine, or a fertiliser spreader.
Sowing dry ensures that the pasture seed is ready to take advantage of the next rainfall to start germination. The seed must remain in close contact with wet soil for about three days to establish a seedling. Sub-soil moisture will sustain the seedling until follow-up rainfall occurs. This rain will also promote the development of secondary roots. This allows the crown of the establishing grass to develop.
Pasture seed in the bottom of shallow tine furrows or small depressions (microsites or surface pitting) in more roughly prepared seedbeds are more likely to establish seedlings because they accumulate water and stay wetter for longer after rain.
A good fallow before planting should release enough nitrogen to allow the grass to establish. Phosphorus may also be required depending on soil analysis or previous experience has indicated a deficiency.
Tolerant of low soil nitrogen levels, creeping bluegrass will compete with native grasses in forest country, where other improved pasture grasses may fail. It responds readily to added nitrogen, especially of legume origin. It is usually uneconomic to apply nitrogen fertiliser to large areas of dryland pasture. Renovation of mature pasture that is showing signs of decline will release nitrogen to rejuvenate the stand for a short time.
Good cultural practices in the season before sowing (pre-cropping or fallow), will help reduce the weed seed population in the prepared pasture seedbed. A light grazing or slashing may be necessary to reduce the competition from weeds in establishing stands. When established, creeping bluegrass competes well with weeds due to its aggressive creeping nature.
Do not graze until follow-up rainfall allows seedlings to develop strong root systems. Initially grazing should be light to encourage runners to develop and spread, but then adjusted to prevent the grass getting tall and rank. Trampling by stock will encourage the runners to take root. Allow the grass to seed in late autumn.
Creeping bluegrass is readily eaten by stock, and can tolerate heavy grazing. The leaf and stem have a strong scent when crushed, but does not taint milk or meat. Low in oxalate, creeping bluegrass will not cause big head in horses.
Creeping bluegrass will respond well to irrigation and any surplus growth makes excellent hay provided its stems are leafy and succulent and not coarse and woody when cut.
Creeping bluegrass seed can be direct headed or collected using a brush harvester. Harvest timing is important as the seed can fall very quickly when ripe.
Other Bothriochloa bluegrasses
Swann forest bluegrass (Bothriochloa bladhii sp. glabra cv. Swann). Forest bluegrass is a natural pasture grass that occurs on forest soils throughout Queensland. Swann, an introduced variety, is a leafy, summer-growing, tussocky perennial, palatable to cattle, that responds quickly to rainfall and will survive heavy grazing.
It has similar cultural requirements to creeping bluegrass and once established can spread from seed into run-down or degraded native pasture of speargrass or pitted bluegrass. Particularly adapted to the traprock country, it is also suited to other low fertility soils receiving above 500 mm annual rainfall. The leaf can be attacked by a leaf rust disease late in the season.
Indian bluegrass or Indian couch (Bothriochloa pertusa) is a smaller type of creeping bluegrass that grows best in a warm climate and has become naturalised in Central and northern Queensland. It is a very drought-hardy plant growing within an annual rainfall range of 500-900 mm.
It has similar attributes, cultural and soil requirements of creeping bluegrass. Of all the pasture strains, Bowen is the least vigorous, earliest flowering, but hardy and invasive of native pasture. Medway is intermediate and the most productive, while Yeppoon is a later flowering leafier strain.
Dawson creeping bluegrass is a low growing, late flowering line used for low maintenance, hard-wearing lawns, roadsides and soil conservation purposes.