Growing Lucerne

Planning

  • Select the best paddocks which are free draining.
  • Lucerne will grow on a range of soils, from deep sands to heavy clays. It seems to perform best on deep sandy loams, alluvial soils, red basaltic soil, red volcanic soil and alluvial flats. It can also be grown on heavier clay soils if infiltration and drainage are adequate and no hard clay pans are present. Good natural slopes or higher elevation are generally recommended. Remember, soil drainage is not always the best indicator, as subsoil may be prone to waterlogging (i.e. hilly Ordovician country).
  • Understanding the limitations of lucerne is important: factors such as low pH, Aluminium and heavy soils prone to waterlogging or poor drainage are areas to be avoided.
  • Check drainage in flood irrigation bays – well-levelled bays with no hollows are required; at least a 1:800 slope, and able to irrigate and drain quickly to avoid lucerne scorch.
  • Plan your crop 12 months to 2 years prior – remove as many weeds as possible during this phase - if high weed burden, a cereal crop or brassica clean-up crop will help prior to sowing. Also consider weed control options in years prior such as spray-topping, spray-grazing and winter-cleaning, depending on the specific weed families you are trying to control.
  • Soil test 0-10cm and 10-60cm for pH, Electrical Conductivity (EC), Aluminium (Al), Phosphorus (P), Potassium (K) and Sulphur (S) levels and correct as necessary (talk to your local agronomist). Apply lime if pH is low. Don’t forget Molybdenum.

Sowing & Early Growth

  • Depending on prevailing conditions and location, sowing can occur in late-winter/early-spring. This allows plants to establish in increasing soil temperatures and allows for good winter weed control prior to sowing.
  • Autumn sowing can also be successful, but only if there has been good control of winter weeds prior. Autumn sowings reduce the risk of a failed spring sowing with a much greater likelihood of rain. This is more suited to winter-active or highly winter-active cultivars.
  • Sow when the average soil temperature is above 8°C in late-winter to early-spring and 14°C in autumn
  • Sowing rates are rainfall and environment dependent – please consult your PGG Wrightson Seeds Sales Agronomist for sowing advice.
  • Ensure good seed to soil contact during the sowing process. This will aid strong, even germination
  • Ensure lucerne seed is inoculated with the correct strain of rhizobium (AL) – this will allow for the development of nodules to fix atmospheric nitrogen and for successful crop productivity and viability.

 

  • Allow the lucerne to reach a minimum of 50% flowering (50% of the tallest stems have a flower) prior to the first grazing/cutting.
  • If irrigation is available, apply water before sowing to ensure adequate soil moisture at the time of sowing.

For established stands, delay irrigation unil 10-14 days after grazing

  • Irrigation encourages weed seed germination
  • When lucerne has been grazed or cut (i.e. its leaves removed) the crop requires minimal water to regenerate leaf cover.
  • Waterlogging can cause roots to rot.
  • Weeds need to be controlled as they take moisture and nutrients away from the stand. There are a range of effective herbicides available for weed control in establishing lucerne stands - consult your local agronomist for details.

If the stand is weedy at establishment it can be grazed/cut when it itis 15-20cm tall and then left to flower a minimum of 50%

Established Stand Management

Weed Control

  • Identify weeds present
  • Always spray in winter for winter-cleaning weed control (i.e. when the lucerne is dormant)

Dryland lucerne stands should be sprayed every second year (at least)

Irrigated lucerne stands should be sprayed annually

  • Consult your local agronomist for chemical recommendations

 

Pests and Diseases

  • Identify early and graze or cut the stand (removing the pest feed source).
  • If pest infestations are high and are causing damage to yield, then using an insecticide is necessary
  • Early winter graze to reduce over-wintering aphid populations.
  • There are numerous Fleas (i.e. Lucerne Flea), Mites (i.e. Red Legged Earth Mite), Grubs, Weevils and Aphids that attack establishing lucerne stands. Monitor early (both beneficial and predators) to prevent rapid population build-up and damage – contact your local agronomist for control options.


 

Fertiliser

  • Soil test annually to ensure fertility is maintained and appropriate fertiliser is used.
  • Leaf analysis during active spring growth can also be used in conjunction with soil tests to check soil fertility and fertiliser type.
  • Apply the recommended lucerne fertiliser after the first cut in spring and then after every second cut, in a cut and carry system.
  • Grazed lucerne requires less fertiliser than hay cutting because nutrients are returned through dung and urine.
     

Irrigation

  • If irrigation is available, this can help when moisture is low. Although lucerne is highly drought tolerant, irrigation increases the potential to more than double the lucerne yield in dry years.

Weed invasion can occur when irrigated too frequently and immediately after cutting or grazing.

  • The optimum frequency and timing of irrigation is dependent on how much water the soil can hold, or your soils’ holding capability.
  • When demand for water is low, delay irrigation until new leaves are visible and are ready to expand and out-compete germinating weeds.
  • Roots grow at 1cm/day. Growth above the ground stops while reserves are put into the roots.

Mixed Swards

If you have never grown lucerne before, plant a pure stand of lucerne and learn how to manage it.

After the ideal areas of your farm for lucerne monocultures are established, there may be an option to look at lucerne/grass mixes on more difficult soils or topography. These range from lucerne with some grass to minimise soil erosion on wind prone sites, through to a grass pasture where lucerne is providing the legume component where other legumes (e.g. white clover) have failed. The management of lucerne/grass mixes is more complex and extra caution should be taken.

Research has shown that increasing distribution of feed over longer periods can be achieved by using companion species with different seasonal growth patterns.

Examples of companion species with lucerne include:

  • Phalaris
  • Chicory
  • Cocksfoot
  • Tall fescue
  • Plantain
  • Subterranean clover
  • Prairie grass
  • Oversowing annual ryegrass, oats or forage ryecorn
  • Undersowing with winter cereal crops

There are many positives and negatives associated with sowing a companion species – such as mitigating the potential animal health issues, but conversely reducing quality hay and herbicide control options. Consult your local agronomist on the best species or sowing practices suited to your farming systems.

Autotoxicity

It is well known that lucerne plants can produce chemical(s) which suppress the germination and growth of lucerne seedlings. This phenomenon is called autotoxicity.

Autotoxicity is difficult to detect and predict, as soil type, rainfall, management, age of the previous stand etc. all play different roles. Older lucerne stands are more prone to it than young stands because of the accumulation of the chemicals - in evolutionary terms the plant is trying to stop its seedlings growing where it already is.

For a thinning older stand, over sow Italian ryegrass (or similar) in autumn to get use out of the accumulated nitrogen and prolong the stand life. Alternatively, drill in a perennial grass and make it a pasture that might last another 3-4 years as your transition paddock.

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