Sphere medic
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Pasture type and use | This is an acid-soil-tolerant annual medic of mid-season maturity. Because of its rooting system it has the potential to yield later into spring than many other annual legume species. |
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Area of adaptation | Areas of the Central West Slopes and Plains, Southern Slopes and Riverina where soils have become too acid for barrel medics to successfully nodulate and fix nitrogen. |
Min. average annual rainfall | 350 mm (winter-dominant rainfall). |
Advantages |
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Disadvantages |
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Soil requirements | Suits pH(Ca) range 4.8–8.0. It is not suited to deep sands or poorly drained areas. |
Varieties | Orion |
Sowing rates: | |
- as only species | 8 kg/ha |
- in mixtures | 4–5 kg/ha |
Sowing time | Autumn |
Companion species | Use with subterranean clover on suitable soils where cropping is a regular part of the rotation. Use murex medic and sub clover where adequate rainfall allows the introduction of murex. |
Inoculation | Inoculate seed with group AM inoculant. |
Major nutrient deficiencies | As for all medics, requires adequate levels of available phosphorus. Sulfur levels should also be monitored. |
Main insect pests | At the seedling stage, sphere medic tolerates redlegged earth mite — it is more tolerant of redlegged earth mite than any current sub clover or barrel medic. However, redlegged earth mite may still attack the flowering medic in spring and cause flower abortion and seed-set reductions.
Orion has not been bred for resistance to bluegreen aphid and has similar susceptibility to that of the medic varieties Santiago and Jemalong. |
Main diseases | Orion is resistant to spring blackstem (Phoma medicaginis). |
Management | This species has large seeds and needs higher seeding rates than some other medics. Light grazing can commence after the 5–6 true-leaf stage. It can be grazed hard in winter without detrimental effects.
Hard grazing post-flowering will reduce seed yields. Grazing needs to be carefully controlled. The large pods are in an accessible position on the soil surface and are attractive to sheep. Large quantities are readily eaten and do not escape digestion. A light incorporation of pods into the soil can reduce ‘pod theft’ by stock and assist in breaking down hardseededness. |
Livestock disorders of particular note | Can cause bloat in cattle. |
Additional tips | Orion is particularly sensitive to herbicides containing MCPA. |
Further information |
Advice on livestock health disorders was provided by Dr Chris Bourke, Principal Research Scientist, NSW Agriculture, Orange. His contribution is gratefully acknowledged.
Photo: Mary-Anne Lattimore, NSW Agriculture, Yanco.