The power of legumes

Lisa Abblitt

Have you ever wondered what an ideal pasture in southern Australia should look like?

The composition of a pasture is very important. For best results a productive pasture should ultimately be 100% desirable species, ideally 70% grasses and 30% pasture legumes, such as clover. You should not be able to see large amounts of bare earth underneath the pasture canopy and good grazing management will be required to keep your pasture in great shape.

We often talk about the grass species that make up pastures, but why should legumes be included?

Legumes belong to the pea family (Fabaceae) and have two main roles, they increase yield and quality of grass pastures and provide nitrogen to feed grasses through the fixation of atmospheric Nitrogen (N). As a stock feed legumes are palatable, highly digestible (70-85%) and high in protein >20%*(Nichols, 2012). Some legumes such as red clover and lucerne are deep rooted and have the potential to reach water deep in the soil profile.

Products like Relish red clover when sown as a sole stand for lamb finishing systems, has the potential to fix upwards of 150 kg of plant available N/ha/year. The crop after Relish can benefit from a large amount of soil available nitrogen.

There are many pasture legume options, in Australia there are 36 annual and 11 perennial legumes that have cultivars registered for use (Nichols et al 2012). Lucerne and red and white clovers were introduced to Australia by the early European settlers, since then other legume species have been bred in Australia to withstand our Australian conditions. Subterranean and annual medics have been the most successful of these, but efforts from Australian breeding programs have expanded our options with additional species such as Hytas Alsike clover.

Relish red clover
Relish Red clover

There is generally a pasture legume to suit any situation. It is important to consider the following:

  • How long do I want a legume to persist?
  • How much rainfall and irrigation do I have available?
  • Soil type and texture, does the paddock have light sandy soils or heavy clay?
  • What is the pH of the soil?
  • What pests and diseases are likely to affect the pasture?
  • How will you harvest this pasture? Grazing systems?

Perennial species will grow all year round with available moisture. Their Nitrogen fixing ability may be higher as they will grow for longer.

Table 1 below: This shows the common perennial legume options and their attributes.

Annual species grow during the cooler part of the year, flowering and producing seed in spring, then die in summer. New plants will grow from seed the following autumn.

Table 2 below: This table shows some of the many annual clovers and their attributes.

Selecting the right legume for the right situation will give you great results especially as they can produce at least 100kg/ha of nitrogen per year (Knox et. al. 2006). They are extremely complementary and can be grown in a mix with grasses, cereals, forage herbs, and brassicas or as a pure stand crop.

*It is important to note that careful grazing is required by cattle to minimise risk of bloat.

References:

Knox J; Thompson R and Campbell S 2006; Species for Profit – A Guide for Tasmanian Pasture and Field Crops

www.dpipwe.tas.gov.au/documents/species-for-profit-book_web.pdf

Nichols P; Pasture legumes in Australia – origins, current use and future prospects www.futurefarmonline.com.au/LiteratureRetrieve.aspx?ID=162662

Nichols PGH, Revell CK, Humphries AW, Howie JH, Hall EJ, Sandral GA, Ghamkhar K and Harris CA 2012; Temperate Pasture Legumes in Australia – their history, current use, and future prospects

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