Is Your Garden Soil Too Salty?
Salinity Levels Can Affect Plants
High salinity levels in soil and water can seriously affect the growth of plants and will degrade the structure of soil. It can cause plant dieback, and even prevent seeds from germinating. It can also encourage salt-tolerant, invasive plants to move in and replace indigenous plants.
So what exactly is salinity? Is it the same white stuff that comes in that blue cylindrical container used to season food? And why is it bad for plants?
The white stuff that comes in a blue container and used to season food is sodium chloride, and yes, it can cause high levels of salinity in soil and water.
Magnesium sulfate, calcium sulfate and bicarbonates can also cause high salinity levels.
A number of events can cause high soil and water salinity.
Over application of chemical fertilizers.
Although organic gardeners choose not to use chemical fertilizers, many people do use them. Either plant roots will take in chemical fertilizers, the fertilizer elements will be washed away by rain or irrigation or they will accumulate in the soil. When chemical fertilizers begin to accumulate in the soil, salinity will begin to rise.
Salinity Seepage
Arid lands and desert salinity is generally caused when saline (salty) groundwater is too close to the surface of the soil or just at the surface. When the water table is within two meters of the soil’s surface, something happens. The air spaces between rock particles in the soil act as a sponge and literally draw the water up to plant root levels. This is called “capillary rise.”
Overirrigation
Over-irrigation can also cause high soil salinity. This in turn causes ground to become oversaturated. Salts seep up through the saturated soil, and when the water retreats, it leaves the salt deposits in the soil.
Saltwater Intrusion
Coastal regions often experience saltwater intrusion. As groundwater is pulled out of aquifers, it is replaced by saltwater.
Plant Damage Caused by High Salinity Levels
- Leaf chlorosis (a yellowing of leaves)
- Stunted plant growth
- Smaller than normal leaves
- Leaves with a blue-green color
- Leaf necrosis (blackening of leaf edges, leaf tissue or entire leaves)
- “Burning” of leaves
- Leaf Drop
- Root Death
- Wilting
Any soil destined for a garden should be tested. Soil testing is easy and inexpensive. Anyone planning a garden should have her or his soil tested. Soil tests will tell the gardener the level of salts in the soil and indicate what plants should be used (usually native or adapted plants), or how the soil should be amended to grow the types of plants desired.
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