Sea-mud varies greatly in its composition, dependant something upon the soil of the neighboring uplands. It is considered a valuable manure in Europe, and is sought for with avidity, and transported not unfrequently considerable distances into the interior. We have seen it used with good effect in the United States, from Massachusetts to Pennsylvania; and are told that in Delaware and Maryland, and even farther south, it is highly prized by those who have tried it. On Long Island, the past summer, we were occasionally shown the fertilising results, not only of sea-mud, but of the marsh soil also, applied to the uplands a little removed from the borders of the marshes and the seashore. Our intelligent correspondent, Mr. Partridge, informs us he has used beach-mud in various ways with good effect; and that the past summer, two gentlemen whose country seats border his mill, were allowed to make use of the sediment from the tide mill-pond, and they found it added greatly to the productiveness of their gardens.

Sea-mud may be applied in different ways, according to its constituents. If it abounds with clay, it should be taken in the fall of the year, and spread broad-cast upon the land, and thus lie exposed to the action of the frost all winter. This pulverises it well, and in the spring of the year the roller should be passed over it in dry weather, followed by the harrow, and if any lumps remain after this operation, let them be beaten fine with the dung-beater. This is considered one of the best top dressings for grass land which can be given; it also answers well to be plowed in for either grain or root crops. Where the mud abounds more with sand, it is an excellent thing to put into barn yards and pig-styes, to be incorporated with the litter and manure; it may likewise be thrown into a heap until it becomes completely pulverised, and then spread upon the land.

As air-slacked lime or small broken lime can be obtained in this city for about half the price of quick lime, Mr. Partridge suggests that it would be an excellent ingredient to mix with the sea-mud, for the purpose of forming a compost. A bushel or two of the lime, to a cart-load of the mud, he thinks a good mixture. When it abounds with considerable vegetable matter, we would recommend a greater proportion of lime, say from one to ten or twenty parts. Ashes and charcoal dust are excellent ingredients to mix with sea-mud, and when either of these or lime is used to form a compost, they make it much more lasting. It is less labor to transport the sea-mud directly to the place where it is to be used, and spread it broad-cast at once upon the land; and as the saving of labor is quite an object in our country, we have found that this method of applying it is the most generally practised.

With the exception of a few of our more intelligent farmers, sea-mud and marsh-mud as fertilizers, are not valued as highly as they ought to be in the United States. They exist in immense quantities all along our seaboard, and may be had in an unlimited extent for the mere labor of transportation. We hope that some experiments may hereafter be made with them by some of our readers on the different kinds of crops, and that they will give us the results. The time, we think, is approaching, when sea-mud and marsh-soil will be as highly prized here as they now are in Europe.