Scientific name(s)
Trifolium subterraneum ssp. yanninicum
Strengths
- Tolerant of heavy grazing under set stocking.
- Vigorous seedlings provide good winter feed
- Adapted to soils prone to winter waterlogging
- Very persistent in high rainfall areas
Limitations
- Poor persistence on well-drained sandy soils
- Insufficient hardseededness for 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
- Some older cultivars have high oestrogen levels contributing to ewe infertility
Plant description
A prostrate self-regenerating annual pasture legume tolerant of waterlogging and heavy grazing that grows from autumn through to spring and buries its burrs.
Pasture type and use
Suited to permanent and semi-permanent pastures and to crop rotations where cropping is infrequent. Other subspecies (subterraneum and brachycalycinum) are better suited to soils not prone to waterlogging.
Where it grows
Rainfall
Adapted to winter-dominant rainfall area of southern Australia with annual rainfall 425 -1200 mm. Midseason varieties suited to medium rainfall zone, later flowering varieties suited to higher rainfall zone. Can also be grown under irrigation.
Soils
Prefers sandy loams to clays of moderate acidity (pHCaCl 4.5-6.5) and good waterholding capacity. Highly tolerant of winter waterlogging.
Temperature
Widely adapted to the agricultural areas of Western Australia, South Australia, Victoria, New South Wales and Tasmania. Good frost tolerance.
Establishment
Companion species
A range of perennial and annual grasses, balansa clover, gland clover, Persian clover, purple clover, burr medic. On paddocks with patches of well-drained soils it can also be sown with subterranean clover ssp. subterraneum (black-seeded subclover) and lucerne.
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. Can biologically fix 25 kg nitrogen/tonne of herbage dry matter.
Fertiliser
Phosphorus (with potassium on deficient soils) at sowing – levels dependent on soil tests. Trace elements (Cu, Mo, Zn) may be required on very infertile soils.
Management
Maintenance fertliser
Annual applications of superphosphate (with potassium or sulphur 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. Burr burial protects the seed from being eaten by grazing animals.
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
Some older varieties of subterranean clover contain high levels of phyto-oestrogens, which can affect the sheep reproductive system. The most active isoflavone is formononetin, which can cause a decline in ewe fertility. Two other isoflavones, genistein and biochanin A, are also present in all subterranean clover varieties, but these have less impact. If ewes are mated when they are grazing green, potent subterranean clover their reproductive performance can be temporarily impaired. Continued exposure over several years to high levels of formononetin can lead to permanent infertility. Ram fertility is not affected.
Formononetin is present in subterranean clover only while the pasture is green. However, hay produced from oestrogenic varieties can be almost as potent as green pastures. Formononetin levels drop away during late flowering. Generally, dry subterranean clover pastures that result from normal haying-off are not oestrogenic. However, if there is a very early finish to the season, it is possible for oestrogenic varieties to retain some potency in the dry state. All recently released varieties have low formononetin levels. There have been isolated reports of cattle bloat on very clover-dominant subterranean clover pastures.
Cultivars
| Group | Cultivar | Seed source/Information |
| mid-season maturing | Gosse | Australian Herbage Plant CultivarsSouth Australia PIR - Fact sheet 36/00Guide to Australian Pasture LegumesSeedmark |
| Riverina | Australian Herbage Plant CultivarsGuide to Australian Pasture LegumesPremier Seeds | |
| Trikkala (older) | Australian Herbage Plant CultivarsSeedmark | |
| Yarloop (older) | Australian Herbage Plant Cultivars | |
| late maturing | Napier | Australian Herbage Plant CultivarsNSW Agriculture Agnote Seedmark |
| Larisa (older) | Australian Herbage Plant Cultivars | |
| Meteora (older) | Australian Herbage Plant Cultivars |
Denotes that this variety is protected by Plant Breeder's Rights Australia
Further information
General informationNSW Dept of Primary Industries - Agnote DPI-268 Qld Dept of Primary Industries and Fisheries - Sub coler for granite and traprock soils Species for Profit: A guide for Tasmanian Pastures and Field Crops Registered cultivars of subterranean clover - their characteristics, origin and identification (1996). Agriculture Western Australia Bulletin No. 4327, pp. 61.Pasture Legumes for Temperate Farming Systems – The Ute Guide, Top Crop Australia. (2004). (Primary Industries and Resources South Australia/ Grains Research and Development Corporation), pp. 147.
Phyto-oestrogensWA Department of Agriculture and Food - Farmnote 41/2005Victoria Department of Primary Industries Agriculture Notes - AG0737
DiseasesFungal diseases of pasture legumes in Western Australia (1989). Department of Agriculture, Western Australia, Bulletin No. 4133.WA Department of Agriculture and Food - Farmnote 207 WA Department of Agriculture and Food - Farmnote 68/1991Victoria Department of Primary Industries: Agriculture Notes - AG0725 Victoria Department of Primary Industries: Agriculture Notes - AG0724
Acknowledgements
Hayley Norman, CSIRO, for comments on feeding value.
Author and date
Phil Nichols (DAFWA) and Brian Dear (NSW DPI)
July 2007
