The cotton-grower who sells cotton lint at 10 cents a pound and the market gardener who sells from $100 to $300 worth of fruits and vegetables from one acre may well make liberal use of commercial nitrogen at 15 or 20 cents a pound; but if after deducting the cost of harvesting, threshing, storing and marketing the average farmer receives only 1 cent a pound for his grain and if 40 per cent of the commercial nitrogen applied is lost by leaching, then the total crop of grain would bring only enough money to pay for the nitrogen required to produce it, at 20 cents a pound. We may sometimes advise the American grain-grower to buy water with which to irrigate his crop, but not to buy nitrogen with which to fertilize it. If the grain farmer grows 40 bushels of wheat to the acre, clover having been seeded on the same land in order to plow under the equivalent of 1-1/2 tons of hay as green manure the following spring, and follows this by a 60-bushel crop of corn and a 50-bushel crop of oats, and this the fourth year by two crops of clover aggregating 3 tons an acre, including 2 bushels of seed, he can thus secure from the air about 180 pounds of nitrogen in the 4-1/2 tons of clover. Moreover, if the first cutting of clover the fourth year is left on the land and the threshed clover straw from the seed crop and likewise all straw and stalks are returned to the soil, only 154 pounds of nitrogen an acre would leave the farm if the total grain and clover seed were sold. With 80 cents a bushel for wheat, 50 cents for corn, 40 cents for oats and $8 for clover seed, the total returns from the four acres would amount to $98. On the other hand the live-stock farmer may grow two 60-bushel crops of corn, followed by 50 bushels of oats and then 3 tons of clover hay containing 120 pounds of new nitrogen. The four crops would contain 350 pounds of nitrogen; and if the grain and hay and half the corn-stalks are used for feed, with the straw and the remainder of the stalks for bedding, it is likewise possible to replace the 230 pounds of nitrogen required for the grain crops, provided not more than one-seventh of the manure is lost before being returned to the land. The important weakness on the common live-stock farm lies in the enormous waste of manure. If 10 pounds of feed produce 1 pound increase in the live-weight of the animals fed, and if they bring 6 cents a pound on the hoof, the gross returns aggregate $107.50 from the four acres, barring losses from accidents, animal diseases, and so on.