THE RANGELAND

What cultivar
 

for pastrures in the Rangeland?

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Physical characteristics

     The rangeland is the zone with less than 200 mm of rainfall that is used for extensive grazing.

The Marginal Zone overlaps the Cereal and Rangeland Zones. The Marginal Zone is the area of cereal cropping used mainly to feed livestock and establish tenure rights.

    The other important feature of the rangeland is that it consists of run off and run on zones.

This is a natural feature of the zone.

Ideally the run-off and run-on should be adjacent (a few tens of metres at the most).

In a degraded rangeland the run off areas are large and run on areas distant.

The water runs into large wadis and is often wasted in salt lakes.

    In Australia there is strong colonisation of medic ecotypes into the rangeland run-on areas.

There has been virtually no sowing of medics but they have been accidentally introduced from the northern hemisphere and have naturally colonised the rangeland.

Cultivars for the 200 to 150 mm zone

    There are a number of excellent medic cultivars from the Early season and Very early season cultivars (see What cultivar for the cereal zone? )

    The most important ones are those with small seed pods.

Serena burr medic, Herald strand medic and Swani disc medic are obvious choices. There are Early and Very Early snail medics that are suited to the rangeland but they should not be sown alone as their large pods make over-grazing of the dry pods easy.

In Libya good medic pastures were established at Adjulat using Australian cultivar where the rainfall was below 150 mm.

    Libya has shown that run-on areas can be seeded with an even larger range of medics including some from the barrel and snail medic species.

    There are many other medics that grow in these low rainfall areas.

In Libya there was in the 1970s and 1980s a systematic collection of 2000 medic ecotypes.

Medics were found in areas with as little as 50 mm of annual rainfall.

There is a lack of commercial seed because of the dominance of Australia in medic seed production.

In Australia the investment in the rangeland is mostly for fencing and other labour saving devices.

The returns from wool are low and few owners invest in pasture improvement beyond a little natural regeneration.

There is no market in Australia for rangeland medics.

Local ecotypes in the WANA region.

    Over-grazing and cultivation have suppressed local medic population to extremely low levels.

There are a few more medic survivors on areas that have been grazed not cultivated but they are still few and far between.

Some medics do exist and will recover once the management environment is changed to favour medic and phosphate fertiliser is applied.

If the long term strategy is to re-seed using pods harvested locally rather than imported seed these local ecotypes will become increasingly important in the pastures.

Their pods will be harvested in greater numbers and the new pastures will continue to evolve from the source pasture mixture.