In the summer-fallow experiments, which have now been continued for twenty-seven years, there has been a great loss of nitrogen. The same remarks apply to this case. No one ever advocates summer-fallowing land every other year, and sowing nothing but wheat. When we summer-fallow a piece of land for wheat, we seed it down with grass and clover. There is, as a rule, very little loss of nitrogen by drainage while the wheat is growing on the ground, but after the wheat is cut, the grass and clover are pretty sure to take up all the available nitrogen within the range of their roots. This summer-fallow experiment, instead of affording an argument against the use of summer-fallowing, is an argument in its favor. The summer-fallow, by exposing the soil to the decomposing influences of the atmosphere, converts more or less of the inert nitrogenous organic matter into ammonia and nitric acid. This is precisely what a farmer wants. It is just what the wheat crop needs. But we must be very careful, when we render the nitrogen soluble, to have some plant ready to take it up, and not let it be washed out of the soil during the winter and early spring. We have much poor land in the United States, and an immense area of good land. The poor land will be used to grow timber, or be improved by converting more or less of it, gradually, into pasture, and stocking it with sheep and cattle. The main point is, to feed the sheep or cattle with some rich nitrogenous food, such as cotton-seed cake, malt-sprouts, bran, shorts, mill-feed, refuse beans, or bean-meal made from beans injured by the weevil, or bug. In short, the owner of such land must buy such food as will furnish the most nutriment and make the richest manure at the least cost--taking both of these objects into consideration. He will also buy more or less artificial manures, to be used for the production of fodder crops, such as corn, millet, Hungarian grass, etc. and, as soon as a portion of the land can be made rich enough, he will grow more or less mangel wurzels, sugar beets, turnips, and other root crops. Superphosphate will be found admirably adapted for this purpose, and two, three, or four hundred pounds of cheap potash salts, per acre, can frequently be used on fodder crops, in connection with two or three hundred pounds of superphosphate, with considerable profit. The whole subject is well worthy of careful study. Never in the history of the world has there been a grander opportunity for the application of science to the improvement of agriculture than now.