Buffel grass in south Queensland
Buffel grass is a deep-rooting, summer-growing, erect tussocky grass. It is the most important sown species in the 400-800 mm rainfall zone of Queensland. The regions covered here are the Western Downs, Maranoa and Warrego.
Establishing buffel grass pastures after clearing timber can give a large initial increase in stocking rate. Buffel is more productive than the native grasses when soil nitrogen levels are high, but it needs moderate levels of soil phosphorus.
Buffel persists well because of its excellent drought tolerance. It is also less selectively grazed than other sown grasses such as green panic.
Buffel shoots quickly after light falls of spring rain and can provide green feed in early winter before frost.
Cattle reach premium condition and market weight on buffel pastures during summer, while allowing native pastures in other paddocks to be spelled.
Buffel grass is difficult to establish on clay soils but establishes well on soils with a loose, soft surface. The most suitable soils are:
- red earths with a friable surface (e. g. some ironbark and poplar box country)
- lighter brigalow and brigalow/belah clays
- sandy soils with moderate phosphorus (e.g. river frontage sands and some cyprus pine country)
- those once under gidgee
- those once under softwood scrub.
Buffel grass types can be distinguished on size, but in practice there is little difference in the productivity of the commonly sown cultivars. The tall buffels (e.g. Biloela) are more suited to the heavier soils, higher rainfall and for cattle production. The medium height varieties (e.g. American and Gayndah) are more suited to lighter soils, lower rainfall and for sheep production.
Seed head colour
American variety has a reddish-purple seed head. Gayndah variety is straw coloured. Biloela variety is straw coloured but may have a reddish tinge.
When to sow
January to late February is the most reliable rainfall period. October to November sowings are more risky because rainfall is less reliable and heatwaves are more common.
Seed rate and pasture mixtures
A rate of 2 kg/ha is adequate to establish a good sward in 1-2 years, given sufficient rainfall. With lower sowing rates, the stand must be allowed to thicken for longer before it reaches full grazing potential. The costs of sowing large areas can be reduced by harvesting seed from grazing paddocks.
Sow buffel grass (1.5-3 kg/ha) alone in August or early September if spring weeds will not be a problem, or in late January-February. Buffel grass should preferably be sown with appropriate legumes.
Recommended mixture options with buffel grass in southern Queensland are:
- sow with barrel medics e.g. Caliph, Jester or Paraggio and/or Toreador hybrid stand/disc medic and/or Cavalier or Scimitar spineless burr medic in March-April (see annual medics )
- sow medics shallow under last cereal crop
- sow with lucerne (2 kg/ha) in late summer to early autumn
- sow with Cattinga stylo, Desmanthus or Wynn cassia.
An ash seedbed or prepared seedbed improves the reliability of establishment. 'Microsites' are particularly important in more arid western areas; these are natural depressions, such as stump-holes, which provide moist areas for seed germination and protection of seedlings from grazing.
Burnt pulled scrub
Buffel is broadcast into the ash seedbed soon after cleared country is burnt. Buffel can also be sown into windrows after stick raking.
The most common form of cultivated seedbed is where cropped country is returned to pasture. The best establishment occurs on a seedbed that has been fallowed for moisture and nitrogen accumulation and for weed control as if preparing to plant a crop. Ideally, 40-60 cm of sub-soil water should be stored in the profile.
Clay soils require 3-4 workings; they should be harrowed before sowing and rolled or presswheeled after sowing. On hardsetting soils, which tend to seal, 2-3 cultivations are adequate. Establishment can be poor on over-prepared, very fine seedbeds on hard-setting soils.
Commercial pelleting of buffel makes it easier to handle and overcomes bridging problems when sowing through airseeders, combines, precision planters and fertiliser spreaders. Insecticides and fungicides can be included in the pellet. Commercially pelleted seed is much more expensive than unpelleted seed. Pelleting seed may not improve establishment.
Seed can be broadcast onto ash seedbeds from aircraft. On prepared seedbeds, seed is broadcast onto the surface and covered by soil to a maximum depth of 10 mm by light harrows, weldmesh or a light chain, or rolled on non-crusting soils, to improve seed soil contact.
Common planters are:
- fertiliser box of a combine with seed agitator
- rolling drum seeder
- 'McMullen' broadcaster
- 'C' seeder
- Crocodile seeder
- hand broadcast (from a vehicle, motorbike or horseback).
Buffel grass germination relies on good rain after planting. The seed must maintain contact with wet soil for 4-5 days to produce a seedling. Sub-soil moisture will sustain the seedling until follow-up rainfall promotes secondary roots that form the crown of established grass plants.
A dry crusted surface can physically prevent seedlings from emerging. Strong weed competition can surpress young buffel grass seedlings; this is a problem in old cultivation if weed control has been neglected in the cropping phase.
Buffel grass has a high demand for nitrogen and phosphorus. A soil analysis, or past cropping history, should indicate the nutrient status of the soil. Generally it is uneconomic to apply fertiliser to extensive areas of buffel grass country - unless it is being used for seed production. Residual phosphorus from cropping may improve the growth of young buffel grass plants.
A young stand should not be grazed until it has seeded, especially where established plants are lightly dispersed. On small areas, electric fencing will help deter grazing by native and feral animals. Patchy or light stands need to be spelled until after rain in the following summer.
Buffel grass has a high oxalate content and horses eating mostly buffel grass may develop big head (Osteodystrophia fibrosa). This can be reduced by maintaining a good legume component in the pasture or by providing a calcium and phosphorus supplement.
The productivity of buffel pastures declines in the years after establishment as available soil nitrogen is tied up in organic matter. Pasture on infertile red soils with lower initial nitrogen levels run down faster than pasture on high fertility clay soils.
Soil disturbance by chisel or disc plough will mineralise organic nitrogen to an available form with the benefit depending on the severity of the soil disturbance. The run-down pasture may be worked one or more times with a chisel plough or disc implement, but more effectively the paddock may be ploughed out, cropped and then replanted.
If seed is to be harvested, grazing should cease on seed blocks after early summer rain. The homemade beater type harvesters are commonly used. Normal yields are 10-60 kg/ha/harvest of clean seed. Nitrogen fertiliser will increase seed yield with adequate rainfall.
Insect pests and disease
Buffel grass seed caterpillar (paralid moth) is the only major insect pest of buffel grass; ergot is the main disease. They both attack seed heads in warmer, higher rainfall areas such as the Central Highlands and Dawson-Callide. Control of both is uneconomic. Do not harvest infected stands.