It is surprising what an effect a few bushels of ground bones to the acre will produce; reference is made to a single experiment, and not an isolated one either. Some six years since, we applied ten to twelve bushels of coarsely ground bones to the acre, on about half of a twelve acre field; on two lands adjoining, was guano, at the rate of 200 pounds to the acre, (the cost of each about the same,) and extending nearly through the field; both were applied in the spring, on the oat crop--and which was decidedly better, by the eye, on the two lands with guano. In the fall, the field was sown with wheat, manuring heavily from the barn yard, adjoining the guano, but not spread on the two lands, or on the boned portion of the field. There was but little difference perceived in the wheat, except from the manure, which was the best--the field having been limed for the preceding corn crop, 80 bushels to the acre. The experiment was made to test the comparative durability of the three kinds of manure; the guano, ground bones, and manure from the barn yard; and the ultimate profit to be derived from each, in a full rotation. After the first crop of grass, and perhaps the second, which was in favor of the manured portion, the succeeding crops of hay and clover seed, have been decidedly better on the boned part of the field. At the present time, and also the past season, this being the fourth year in grass, the guanoed lands present about the same appearance, that does a small adjoining space, purposely left without manure of any kind, lime excepted. The manured part affords good pasture, but is quite inferior to the boned, which would give a fair crop of hay, and probably three times as much grass as the two lands with guano. It is believed that the increased crop of clover seed on the boned, over the guanoed portion, paid for the former; and that the two crops of clover since taken from the field, have paid, or nearly so, for the lime or other manures applied. This evidence corresponds with the opinion of Professor Mapes; that is, that the value of an application of guano is greatly enhanced by the addition of phosphate of lime, in some shape; the guano acting immediately and producing a direct profit, while the slow action, for which some farmers cannot wait, keeps up the fertility for years, or until the owner may find time to profit by another application of guano. We quote again a few more of the very sensible remarks of friend Stabler. "I am an advocate for the liberal use of all kinds of manure, guano included, if the price will justify it. A farmer had better buy manure than to buy grain, if compelled to do either; for we cannot expect much from nothing, or reasonably calculate upon improving very poor land without manure of some description, unless plaster will act with effect; nor is this generally the case without the land possesses naturally, some particular source of fertility, not wholly exhausted by bad or improvident tillage.