Sulla (Hedysarum cornarium) is a widely used perennial forage legume in central and western Mediterranean countries. It has been used commercially in North America for the past 30 years. While an individual plant can live for up to two years, sulla can easily regenerate from seed which allows for a paddock of sulla to continue to produce for a number of years.
Sulla is best suited to similar soil types to those ideal for lucerne; neutral to slightly alkaline with a pH range of 5.5 - 8.5 (CaCl2). It is adapted to alkaline calcareous soils in South Australia, Northern New South Wales and Southern Queensland. Water logging will result in plant death and therefore reduce the life of a sulla stand.
Wilpena sulla is an exciting new biennial forage legume suited to neutral - alkaline soils, ideal for short pasture rotations in both mixed farming and livestock production systems.
Wilpena has a high yield potential and is highly palatable, with excellent forage quality leading to outstanding animal performance. Wilpena is non-bloating and has reputed anthelmintic qualities which may reduce worm burdens. It also has the potential to fix high levels of nitrogen.
Wilpena sulla is yet to be truly tested in marginal areas of Australia. In preliminary evaluation trials conducted in South Australia and Northern New South Wales, there are indications that it can produce in excess of 20t DM/ha over two years in a low to medium rainfall environments (400mm - 550mm) given favourable conditions. In Queensland, Wilpena sulla has produced between 8-12t DM/hain the first year in moderately good rainfall conditions.
Wilpena sulla is a branching, erect plant that has the potential to grow as high as 1.6m, but will commonly grow between 0.3m to 1m.
Wilpena has a deep branching taproot that allows the plant to source moisture and nutrients from deep within the soil profile. It’s this root system that also gives Wilpena an extended growth period during late spring and early summer prior to the plant shutting down and going dormant during the hot summer months.
Wilpena sulla is recommended as a specialist crop in both cropping rotation and/or pasture systems. In terms of productivity, it is more productive than persian clover or red clover and allows for a shorter rotation than lucerne.
Nodulation is very important to the survival of Wilpena sulla and with the high production ability of the species; soil nitrogen levels are potentially very high and extremely valuable given the cost of chemical based nitrogen fertilisers. While the fixed nitrogen is present in the soil, it is released slowly over a 2-4 year period.
The leaves are similar to a fern-like structure with between 5-15 pairs of oval to round leaflets and a singular leaf at the end.
The stems of the plant are thick and succulent through the growing period. However, once flowering commences, the stems become woody and this continues until the plant dries off and goes into its dormancy phase.
Prepare a fine, firm weed free seed-bed prior to sowing which is important for all small seeded species. Wilpena sulla can be sown in early autumn, late winter or early spring. The use of a roller or press wheels ensures good seed to soil contact and moisture retention is optimised.
Wilpena should be coated with Superstrike® and be sown at 10 kg/ha and seed drilled no deeper than 10mm. A target establishment rate is 25 plants per m2.
Wilpena is best sown as a pure legume stand as it doesn’t compete very well against most other species. The key to success for sowing Wilpena with companion species is to establish it in the first season and then look at a companion species such as clovers in the second year.
Wilpena has been bred to be more upright in its growth habit and as a result is best suited to produce high quality forage; either silage or hay. Wilpena can be grazed, but correct management needs to be implemented to get the most out of Wilpena as well as ensuring stand survival.
Wilpena is best managed with rotational grazing. Grazing intervals will vary from 35 to 85 days depending on moisture, day length and soil temperature. It is advisable that in the first year, Wilpena should be lightly grazed to ensure good root establishment and second year plant density.
Avoid grazing when the soil is wet, especially with cattle so as to minimize hoof damage and pugging.
Allow regrowth of at least 30-40cm (12-16 inches) before grazing again with both cattle and sheep.
Do not graze below 10cm as this will slow regrowth potential down considerably.
It is well documented that pasture species which produce high levels of protein cause bloat in cattle. Though Wipena is high in protein, it produces condensed tannins which assist in the prevention of bloat in cattle.
Wilpena can be successfully ensiled or made into hay, producing high quality, highly digestible feed.
Where Wilpena is the main component, lactic acid content may increase, reducing the ammonia concentration and therefore lowering the pH resulting in high quality silage.
For optimum hay quality, Wilpena should be cut prior to peak flowering (aim for 10% flowering) with a mower conditioner. This is critical due to the thick nature of the stems that need to be conditioned so as to aim with the drying process. The height for cutting the Wilpena will also aid in the drying process so as to allow air flow around the entire windrow. Ideal height for cutting off the ground is between 15–30cm. Growers need to keep any raking to a minimum so as to keep the leaf of the plant, otherwise the hay result will be primarily stem which lowers the quality.
Minimum 400mm rainfall per annum unless irrigated