Subteranean/Sub clover/ssp. brachycalicinum

Subteranean/Sub clover (ssp. brachycalicinum) plant

Scientific name

Trifolium subterraneum ssp. brachycalycinum

Strengths

• Tolerant of heavy grazing under set stocking.

• Vigorous seedlings provide good winter feed.

• Very persistent in high rainfall areas and other areas with infrequent cropping.

Limitations

• Requires cracking or stony soils to bury its burrs.

• Insufficient hardseededness for reliable persistence in tight cropping rotations (1 year crop:1 year pasture).

• Susceptible to germination following ‘false breaks’.

• Shallow-rooted, so unable to capture deeper soil moisture and susceptible to premature death in dry springs.

Subteranean/Sub clover (ssp. brachycalicinum)

Plant description

A prostrate self-regenerating annual pasture legume tolerant of heavy grazing that grows from autumn through to spring.

Pasture type and use

Suited to permanent and semi-permanent pastures and to crop rotations (with at least 2 years between crops). It is best suited to neutral-alkaline cracking or stony soils, while the other subspecies (yanninicum and subterraneum) are better suited to acid soils.

Where it grows

Rainfall

Adapted to winter-dominant rainfall area of southern Australia with annual rainfall 425 -800 mm. Midseason varieties suited to medium rainfall zone, later flowering varieties suited to higher rainfall zone. Can also be grown under irrigation.

Soils

Prefers well-drained, neutral-alkaline (pHCaCl 6.0-8.5), cracking and self-mulching or stony loams and clays.

Temperature

Adapted to the agricultural areas of South Australia, Victoria, New South Wales and parts of south-east Queensland on appropriate soil types with sufficient winter rainfall. Good frost tolerance.

Establishment

Companion species

A range of perennial and annual grasses, lucerne, subterranean clover ssp. subterraneum, biserrula, rose clover, purple clover, balansa clover, Persian clover, barrel medics and burr medics, depending on soil type.

Sowing/planting rates as single species

5-15 kg/ha.

Sowing/planting rates in mixtures

3-8 kg/ha, depending on the number of mixture components.

Sowing time

Sow April-June, into moist soil following good weed control. Shallow sowing (<40 mm) is essential.

Inoculation

Commercial Group C (subterranean clover). Granular clay inoculants can also be used. Will biologically fix about 25 kg nitrogen per tonne of dry herbage produced.

Fertiliser

Phosphorus (with potassium or sulphur on deficient soils) at sowing – levels dependent on soil tests.

Management

Maintenance fertliser

Annual applications of superphosphate (with potassium on deficient soils) are required to achieve maximum productivity. Levels are dependent on soil tests.

Grazing/cutting

Thrives under set stocking and can be grazed moderately hard while flowering. Likely to be shaded out from more erect plants under lax grazing. Can be cut for hay.

Seed production

Requires vacuum harvesting. Seed yields of up to 1000 kg/ha can be achieved under ideal conditions.

Ability to spread

Slow spread from site of sowing. Can spread by burrs attaching to wool.

Weed potential

Its slow rate of spread, its preference for moderate-high fertility soils and specific rhizobia requirement gives it low potential as an environmental weed. It is readily controlled by a range of broadleaf herbicides within crop.

Major pests

Redlegged earth mite is a major pest, particularly at plant establishment, where it can kill emerging seedlings, but also causes damage in spring. Timerite® has proved an effective means of control. Lucerne flea and blue green aphids can also cause damage in spring. Refer to chemical labels for suitability and recommended rates for insecticides.

Major diseases

Some cultivars are susceptible to the foliar disease clover scorch (Kabatiella caulivora), found in high rainfall, humid areas. Other foliar diseases in higher rainfall areas include leaf rust (Uromyces trifolii-repentis), powdery mildew (Erysiphe polygonii) and cercospora leafspot (Cercospora zebrina). Several root rots can attack subterranean clover, causing most damage to emerging seedlings and young plants. They include Phytophthora clandestina, Fusarium avanaceum, Pythium irregulare and Rhizoctonia solanii.

Herbicide susceptibility

Refer to chemical labels for suitability and recommended rates for herbicides registered for use on subterranean clover.

Animal production

Feeding value

Excellent as green feed with in vitro digestibility in the order of 70% and crude protein over 20% until mid-flowering. Quality reduces once plants hay off. Dry herbage feeding value over summer is less than maintenance value (often < 50% in vitro digestibility) although animals may be able to obtain sufficient energy and protein by digging up seed burrs.

Palatability

Readily consumed by livestock, either as green or dry feed.

Production potential

Vigorous seedlings provide good early season production. Later flowering varieties capable of more than 10 t/ha annual production in long-season environments.

Livestock disorders/toxicity

No commercially available varieties of ssp. brachycalycinum subterranean clover are oestrogenic and ewe infertility will not be affected. There have been isolated reports of cattle bloat on very clover-dominant subterranean clover pastures.

Cultivars

Group	Cultivar	Seed source/Information
mid-season maturing	Mintaro	-
	Clare 2	Seed Distributors
	Clare (older)	Australian Herbage Plant CultivarsSeedmark
	Rosedale (older)	Australian Herbage Plant Cultivars
late maturing	Antas	PlantTechSeedmarkStephen Pasture Seeds
	Koala (Nuba)	Australian Herbage Plant CultivarsSeed Distributors

Denotes that this variety is protected by Plant Breeder’s Rights Australia

Author and date

Phil Nichols (DAFWA) and Brian Dear (NSW DPI)

July 2007