Until recently the main annual legume for south-west dairy pastures has been subterranean clover.
Nine cultivars are recommended over the area to suit the variation in soil conditions, length of growing season and grazing management e.g. Trikkala, Riverina, Junee, Gosse, Larisa, Denmark, Goulburn, Leura and Meteora.
Other annual legumes including balansa clover and yellow serradella have also been successfully grown in dairy pastures. In the past few years a much wider choice of suitable annual pasture legume species has become available for dairy pastures.
Collectively they are called ‘Alternative’ legumes or ‘Aerial seeding’ legumes and include crimson, arrowleaf and persian clovers.
In addition, new cultivars of balansa clover and serradella are also available. More alternative legume species are expected in the near future e.g. purple, gland, bladder clovers and others.
Integration into subterranean clover pastures:
Alternative annual pasture legumes are a genetically diverse group that are well adapted to the wide range of soil and environmental conditions experienced throughout the dairy areas. When integrated into the standard subterranean clover monoculture based swards it is anticipated that they will significantly increase the legume density, yield and quality.
It is also anticipated that these new mixed swards will have less undesirable volunteer species and to be less affected by diseases and pests. In comparison with subterranean clover the alternative legumes are generally more erect, i.e. taller, have an indeterminate growth pattern, i.e. the potential to exploit favourable spring conditions and have deep roots.
They also have aerial flowers and seed. Alternative pasture legumes are particularly well suited to silage fodder conservation and will allow more flexible techniques such as fodder cropping. Use of these species by farmers will increase milk production by allowing higher stocking rates.
There could also be higher production per cow through higher quality pasture being available at the beginning and end of the growing season and higher quality conserved fodder for feeding in summer and autumn.
Establishment:
To successfully establish and maintain swards of alternative legumes the ‘best practice’ management will need to:
- select suitable paddocks;
- select the most suitable mixture of species and/or cultivars;
- inoculate and lime pellet each alternative legume species, with serradellas to be inoculated but not lime pelleted;
- establish by drill sowing rather than topdressing seed;
- maintain a high soil nutrition level;
- control weed and insect competition before and after germination;
- graze the sward to promote the growth of the sown legume component;
- manage the sward for either grazing and long-term persistence or, as a fodder crop for silage or hay.
Paddock selection:
Good long-term ‘best practice’ management of the paddock soil and weed/insect burdens before establishment is essential for any pasture species, legumes or grasses alike. Test for soil pH and apply lime if needed. Knowledge of the soil type, drainage and nutrition is needed to make a selection of the appropriate species.
Additional management may be needed if the paddock soils have non-wetting or compaction problems. Certainly, the control of weed and insect populations in the year prior to establishment will be advantageous.
Suitable alternative legume mixtures:
Due to the variation of weather conditions between seasons and also the variation of soil types and soil limitations, for example, drainage, nutrition, water holding capacity, within paddocks a mixture of two or more alternative legume species, or two cultivars of the same species, is recommended.
Each species will find their niche in the paddock where its competitive growth characteristics will assist establishment and persistence relative to the other species in the mixture. In addition, a mixture containing both soft and hard seeded species will allow good legume density and growth in the short- and long-term.
In the short-term the soft seeded species will dominate because they would readily germinate in year two, however, in the long-term they do not persist as well as they are vulnerable to summer rain. In year three onwards, the harder seeded species will dominate because they would now have had sufficient time to soften.
Crimson clover and French serradella cv Cadiz are examples of soft seeded species, whilst yellow serradella e.g. cv Avila in addition to balansa, some persian e.g. cvs Prolific and Nitro Plus and arrowleaf clovers all have relatively high hard seed characteristics.
However, pasture swards containing different legume species with different growing characteristics may present challenges in grazing and fodder conservation management. In general terms the selection of which mixture of species or mixture of cultivars will depend on a wide range of factors.
These will include soil conditions, growing season conditions, insects, weeds, diseases and grazing management.
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