Other salts may be sodium or chloride, and are generally considered harmful to plants. So, to avoid tree damage, you must mix composts well with soil, and use modest rates. Trees planted into too-salty soil will be slow to break buds, and will grow slowly, if at all, early in the season. Those that survive often put on a burst of growth from mid-season to Fall, if excessive salts were leached away from the roots. As the salt index of the compost increases, you must lower your rate per acre or per tree.
Young trees are especially sensitive to salts from any source, including conventional fertilizers.
There is a variable amount of water in compost. It often has 50-60 percent water by weight, even when the product seems fairly dry. It is the dry matter in the compost that is important, so you should do a moisture test, and pay by the adjusted dry ton. Spread it on the kitchen table to air dry. Spread the product on paper in a dry, well ventilated shed.