Road salt is generally
pretty bad for soil. Even if the amount of residual salt that collects in your garden is not
at a level that is actually toxic to
your seedlings, the sodium causes swelling and dispersion of clay particles
through the soil, clogs soil pores, and reduces infiltration and
drainage.
To ensure the proper
growth of plant life, your soil must contain proper levels of nutrients in
usable form. The most important elements
for good soil are carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium,
iron, magnesium, and sulfur. Calcium, nitrogen, potassium and sulfur are the most volatile and dissipate rapidly. The toxicity of road salt spilled into your garden and the degraded soil strucure that results can not only poison your plants but also severely limit the nutrients available to them.
An application of
agricultural gypsum helps the recovery of soil damaged by road salt. Agricultural
gypsum is made from quarried anhydrite gypsum, ground to a very fine
particle size for effective agricultural use. Anhydrite (CaSO4) is a
very pure form of calcium sulfate that lacks the two water molecules present in
common gypsum (CaSO4 · 2H2O).
When road salt (Sodium Halite, NaCl) is dissolved in water, the sodium
separates from the chlorine as a positive ion.
The calcium from the gypsum quickly moves in to replace the sodium which
is then leached out. A mild amount of acid is left in the soil, along with some calcium that is usable by the plants. The lowered pH (higher acidity) makes potassium more available to the plants.
Agricultural
gypsum is sold in better garden supply stores in the area. Careful application will condition your soil and minimize the damage from road salt. A comprehensive soil test of your garden every three or four years is a good way to monitor changing conditions. Soil test kits are available from the county agricultural agent (550 West Hanover, across from the Police Academy) for $15.00. Analysis is performed in a Rutgers lab and the results are detailed and extensive.
