These refined products may be shipped around the world, while the raw materials may not be profitably transported beyond the county in which they are raised. Moreover, the farmer has the profit which comes from manufacturing the raw materials into refined products. (4) In the production of these finer products much of the essential materials of plant growth are left upon the farm. The experiments of Lawes and Gilbert show conclusively that in fattening animals more than nine pounds out of ten of the essential fertilizing ingredients of the food reappear in the solid and liquid excrements. Prothero says: "Farming in a circle, unlike logic, is a productive process." The fiscal policy of one of the great nations of the globe is based upon this idea. Everything possible is done by Germany to encourage the keeping of live stock, because the more live stock that is kept, the more productive will be the soil. The larger the crops raised the more people will be required to harvest them and the larger will be the population to recruit the army and navy. The Kaiser and the German scientist recognize that the fighting force of the Empire is related to the number of domestic animals reared. The meat supplies of the people are, therefore, taxed to bring about this end. (5) The rearing of live stock makes it possible to arrange a better rotation of crops. A five-year and, even better, a six-year rotation, is more effective than a four-year in maintaining the crop-producing power of the soil and enables the farmer to reduce his cost of production. It is possible to keep a larger proportion of the farm in grass and other forage crops, thus reducing the amount of land plowed annually and at the same time decreasing the exhaustion of the land, provided the forage crops are fed to live stock upon the farm. There is an old Flemish proverb which reads: "No grass, no cattle; No cattle, no manure; No manure, no crops." The point of this proverb is that good grass is the basis of good agriculture. Investigations have shown that one may go farther and say that one of the most ready means of increasing the crop-producing power of the soil is by adding fertilizers to grass land. The large number of plants per acre enables the plants to utilize the fertilizer to the highest degree, and plowing under the resulting dense sod is one of the most effective methods of enriching the soil. (6) Animals require constant care, thus making possible a more constant use of labor and other capital. The wheat farmer of North Dakota sows his wheat in April and May and harvests it in July and August. He usually threshes it immediately, and is practically without employment for himself, his teams or his men from September until April. On live stock farms the labor employed in the summer in the field is needed in the winter in paddocks and stables.