We are indebted to the Rev. C. Springer, of Meadow Farm, Ohio, for the Agricultural Report of Ohio for 1851, in which we find- much that is valuable to the Agriculturist, We select the following from it, which touches the question of the rotation of forest trees,” published on page 302 of our last volume. In a state of nature, soils do not deteriorate, but are maintained in a state of uniform or increasing richness. The trees and pla nts of spontaneous growth, are of various kinds. Each takes certain elements from the soil, and from the air, the rain, and dew; but the decay of the various parts of the trees and plants, and the reli- q uice of the various animated beings that subsist on animal life, restore to the soil those elements that had been taken from it, except the small quantity removed by the washing action of water—and even this is compensated on the hills by the washing away of the surface soil, and exposing fresh mineral matter to decomposition—and on the low grounds by their receiving the exhausted materials washed from the higher. Trees draw their mineral elements from a greater depth than the roots of smaller plants, and by their decaying leaves, furnish both organic and inorganic food to themselves, as well as to the smaller plants beneath them." The excrementitious parts of one plant serve as foot:! to others, so that certain associations of plants ami trees are always found, in a state of nature, to characterise certain kinds of soil. There is a natural rotation of timber growth so that as soils become more or less loaded with excrementitious matter, so as to be no longer capable of prod ucing a vigorous grow th of the same trees and plants, another growth of different plants anrl tropi snccpflds. This order of succession has been partially traced by Rev. C. Springer, But many and long continued observations will be necessary to trace out the natural rotations of the dit ferent kinds of timber, on the different kinds of soils. The kinds of rotation best lor some of the annual plants -raised for the food of man and animals, on somekinds of soils have been ascertained, but little is known of the general laws that may and ought to be ascertained. Under culture, soils deteriorate unless they are regularly manured. The removal of any crop, natural or artificial, removes elements that must be restored, in order that its fertility should not be impaired. Mineral acids, alkaline earths, silica in a soluble state, chlorine, iron, &c., are removed, equal in weight to the ash that would be obtained by burning the plants removed. Most of these elements exist in a very minute proportion in the soil in a state to enable the roots to absorb, and plants to assimilate them, so that continue cropping, without returning any thing, flaiJ soon exhaust one or more ot these elements, and the land becomes poor, and must be mar nured with something to elements—or it must be left at rest in fallow, as it is called, to give time tor more ofthe mineral elements to be liberated, by the gradual decomposition of the particles of minerals in the soil. Crops removed from the ground carry away not only a large amount of vegetable matter, but also those mineral materials taken up by plants, small in amount, it is true, but- indis pensable to the perfection of the plants raised. The straw, stalks, and leaves of the plants, if returned, restore in part the waste; b ut still the phosphates which enter in large proportion in the mineral elements of the seeds, are found in mall proportions in the other parts of the plants, and the soil becomes gradually impoverish ed of the elements which are mall in amount in all soils, but which are indispensable to the growth and perfection of the seeds ot, plants. Soils may be and frequently are capable of producing a rank grow th of straw, which produce a small yield of grain. Plants will not produce more seeds than they can perfect. Of the exact composition ot the soils of Ohio, little is known, as few analyses have been made. Of the exact composition of the various grains, plants, and their different parts, as well as vegetables, comparatively little is know; but the relations of the plants and the soil on which they grow, and what and how much is taken from the soil by these plants in each stage of their growth, and how much is removed by our mode of culture, are important facts to be known to the farmer. It is not mere cropping alone with gram, that causes a deterioration in our soils. The flesh, wool, hair, horns, bones, butter, cheese, produced by grazing and marketing our film products, carry away large quantities of elements trom the soil that impoverish it, and diminish its productiveness. The results of this system are now beginning to be felt as much in the dairying, grazing, and sheep farms of Ohio, as where grain has long been raised. The mineral elements removed in the numerous agricultural products are more or less concentrated in cities and villages, where they are permitted to be lost, or they are sent to far distant markets, where they are lost for ever.