Level of confidence in saltland legumes

1.         Farmer experiences
Farmer experiences with saltland legumes tend to be episodic, and some persistence is clearly required as indicated in the case of Trevor Egel in SA:

"The saltier land tends to be too wet for lucerne in most years. Across a paddock there might be variations in surface elevation of only ten or so centimetres, but this will be enough to strongly favour one pasture species over another.  After years of trying to establish either just lucerne with barley (for forage) or just pucci with burr medic, we have learned that it is far more effective to sow them all together and let each find its niche.
This also helps us deal better with the seasonal variations, so that if the season is particularly wet and wipes out the lucerne, we still have the pucci to fall back on.”

2.         Research
There has been and continues to be an active research program to improve the salinity tolerance of legumes.  This combines breeding and selection of more salt tolerant legumes, underpinned with finding or selecting rhizobia bacteria that are also salt tolerant.  Finally, a ‘salt-tolerant’ symbiotic relationship between the legume and the rhizobium must be able to form in the hostile environment of a saline soil.  These three quite significant challenges need to be overcome simultaneously, and so far they have not.

3.         Risks and challenges
The most significant challenge for ‘salt-tolerant’ legumes is that they are not very salt-tolerant, and the combination of tolerances to salinity and waterlogging (conditions common on saltland) is rare.

Many of the potential saltland pasture legumes are annuals and so have to re-establish each year in salty sites – this tends to make balansa clover in particular a ‘one year wonder’ on saltland.

4.         Future prospects
Legumes for saltland have been described as the ‘holy grail’, and would give the economics of saltland pastures a considerable boost from a combination of quality forage and N fixation.  However, the gap between current reality and the ‘exciting future prospects’ for legumes in saltland is considerable. 

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