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Why is Salinity Important?
Constant shallow watering during drought periods can result in elevated levels of salts in the top soil. Salinity results in rapid uptake of salts to toxic levels, This can badly damage or kill trees. Fruit tree's are generally considered to be sensitive and a reduced yield can be experienced even with fairly low levels, because:
- water is naturally attracted to higher salt levels - if soil is high in salt, it binds the water strongly and becomes difficult for the tree to extract (ie. in effect, the saline soil reduces the available water)
- excesses in some salts (Eg. sodium and chloride) can poison the tree.
- excess salts taken up by the tree are stored in the woody tissues
Symptoms of salt damage include:
- leaf burn
- leaf drop
- reduced vigour, yield and size
- trees may appear wilted (despite moist soil)
- chloride and sodium present in leaves.
| Species of Fruit | Salinity at initial yield
decline (threshold) (ECe) | Yield decrease per unit increase
in salinity beyond the threshold (%) |
| Apple | 1.0 | 18 |
| Almond | 1.5 | 19 |
| Apricot | 1.6 | 24 |
| Grape | 1.5 | 9.6 |
| orange | 1.7 | 16 |
| Peach | 1.7 | 21 |
| Plum | 1.5 | 18 |
| Pear | 1.0 | - |
(Source: Guide to best practice water management - orchard crops, Page 51-53)
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