As observed by Johnson, the “demand made on the soil or on fertilizers by the tobacco crop, is for certain reasons greater than that made by other crops which receive more of nearly every kind of plant food. Hay is more exhausting than tobacco as measured by total export from the soil, but grass grows the whole year throughout, save when the ground is frozen or covered with snow, or for more than 8 months. The period of active growth which is required to mature a hay crop, begins indeed in April, and is finished by July, a period of 3 months, but during the year previous, for at least 5 months, in case of the first crop, the grass plants have been getting a hold upon the soil, filling it with their roots, and storing up food in their root-stocks or bulbs, for the more rapid aftergrowth. Tobacco on the other hand cannot be set out in the field before about the 10th of June, and should be in the shed in about 3 months. Its growth then must be a very rapid one, and the supplies of food in the soil must be very abundant so that the quick-extending roots may be met at every point with their necessary pabulum. A crop of 1260 lb. dry leaves requires about 1100 lb. of dry stalks to support the leaves, making a total of 2360 lb. of dry vegetable matter. As new hay contains not less than one-sixth of moisture, we increase the above dry weight of the tobacco crop by one-sixth, to make a fair comparison, and obtain as the yield of an average tobacco field 2750 lb. of air-dry vegetable matter, or more than 1⅓ tons. The matter stands then thus: An acre of first-rate grass land yields as the result of 8 months’ growth, 2¾ tons of crop, while the tobacco land must yield 1⅓ tons in 3 months. “If the above data are correct, the _average_ rate of growth of tobacco is greater than that of a corresponding hay crop, in the ratio of 9:7. The real disparity is, however, much greater. The principal growth of tobacco is accomplished in the hottest summer weather, and in a period of some 40–50 days. Very heavy manurings are therefore essential to provide for its nourishment, and the more so because the best tobacco lands are light in texture, and may suffer great loss by drainage, evaporation, and decomposition.” From these premises, Prof. Johnson advances to the question of what should or should not be presented to the plant in the form of manure. He commences with a caution that, in general, growers must “avoid employing fertilizers which contain salt or other chlorine compound in raising wrapping or smoking tobacco. It is evident, also, that there is no occasion to use any fertilizer for the special object of supplying phosphoric acid, since the heaviest export of this substance does not exceed 10 lb. per acre, annually. It may be well to mention here that phosphates which may be put upon a tobacco field, in guano, &c., cannot suffer waste by washing out, and will come to use when grain or grass shall follow in the rotation.”