Answer: Salt hay is certainly an excellent mulch and is often suggested in areas where it is readily available and therefore somewhat less expensive. You might be able to store it if it is dry enough when you collect it and then stored dry. However, it will deteriorate over time no matter what you do.
Since one of the purposes of an organic mulch is to allow it to deteriorate and thus feed the soil, you might wish to consider some alternative types of less expensive mulch. Straw, for example, works very well in the garden, as do chopped leaves and leaf mold. If you prefer the appearance of salt hay, perhaps you could use a base layer of less expensive material and and top it with the salt hay for looks. Good luck with your project!
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