KEY research findings by the Department of Agriculture and Food WA (DAFWA) have found that subterranean clover remains the best companion legume for kikuyu.
DAFWA’s Phil Nichols worked through options available to growers in the region at last week’s Better Pastures Workshop in Albany.
He started off by outlining the benefits of annual pasture legumes in a kikuyu pasture.
“Annual legumes have the benefit of increasing animal production,” he said.
“They have high digestibility in winter and early spring and high protein levels.
“They fix nitrogen into the soil and improve productivity of companion pasture species and are beneficial to increasing yields and protein levels when grown in rotation with crops.
“Annual pasture legumes also regenerate naturally without the need to re-sow.”
Dr Nichols said when choosing a pasture legume to use as a companion to kikuyu, it was important to be aware of several requirements.
These include adaptability to set stocking or regular close grazing, which is the preferred grazing management for kikuyu.
“It must also have the ability to set seed under grazing with vigorous seedlings,” he said.
“The tops need to emerge through the kikuyu thatch and canopy and rapid root establishment is important so it can cope with any soil drying in autumn.
“An ability to out-compete weeds and resistance or tolerance to red legged earth mites and other pests are also important considerations.”
Dr Nichols said sub clover was the most widely sown annual legume on the South Coast.
“It has a high grazing tolerance, prostrate growth and the flowers are close to the ground,” he said.
“It buries its seed and persists under set stocking.”
Being aware of what variety works in your area is a key consideration when choosing a sub clover.
“Pastures are generally sown to last several years, so long-term performance must be considered,” Dr Nichols said.
“The variety needs to fit in with your farming system and rainfall zone.
“You need to match flowering times to growing season length, soil type and drainage.
“Flowering time is the most important character that delivers a variety to fit an environment.
“Often you may need to compromise and look for something that optimises feed production but allows seed set before the onset of summer drought.”
Dr Nichols said a consideration for sheep producers was oestrogen levels.
“Some of the older cultivars have high levels of formononetin (oestrogen compound), which can lead to difficult lambing or ewe infertility,” he said.
“Newer cultivars are tested for lower levels of formononetin.”
The other issue to deal with in terms of sub clovers is red legged earth mite (RLEM).
Dr Nichols said new varieties released recently carry RLEM resistance.
“RLEM is a major pest for pasture legumes,” he said.
“It can kill emerging seedlings and reduce biomass and seed production.
“There are new sub clovers that carry RLEM resistance at the cotyledon stage.
“These include Rosabrook (suited to greater than 650 millimetre rainfall), Narrikup (500-70mm rainfall), Bindoon (425-600mm), Forbes (350-500mm) and Tammin (300-450mm).
“These are very effective at low to moderate RLEM density, but provide less of an advantage under higher RLEM infestation.
“RLEM still needs to be controlled to protect new sowings and at times of high infestation.”
Dr Nichols said that for more infertile, acidic sandy soils, serradellas were a good option.
“Yellow or French serradella seem to perform the best in this area,” he said.
“Yellow is well adapted to deep, infertile soils as it is deeper rooted than sub clover.
“It is hard seeded and well suited to fit into crop rotations.
“French is also deep rooted and while the seed is cheaper than Yellow, it is less robust.
“Some systems have had success with a mix of French and Yellow.
“The establishment costs of French is cheap, farmers can grow their own seed, pods can be header harvested.
“And then break into segments so they can be sown directly.”