16 A STUDY OF FARM ANIMALS 



cities, largely replacing the horse in this service, still the 

 work horse, and especially the one suited for heavy draft, is 

 here in constant demand. The tractor is well adapted to 

 certain farm operations, supplanting the horse, but this ani- 

 mal is yet indispensable for many purposes on our farms, 

 and will always be an important part of farm equipment. 

 Professor T. F. Hunt states* that in England it is estimated 

 that two horses will cultivate 80 acres of light and sandy 

 soil or 60 acres of heavy, or clay, soil. In the United States, 

 it appears that one horse or mule of working age is kept for 

 every 30 acres of improved land; but in level prairie sec- 

 tions far more service than this indicates is expected. 



The use of domestic animals in maintaining soil fertil- 

 ity has long been recognized as of great importance. The 

 earliest writers on agriculture, who lived just prior to the 

 Christian era, about two thousand years ago, wrote more 

 or less of the value of manures in keeping the soil fertile. 

 The farmer of those days learned from experience that, if he 

 took a crop from the land one year, the next harvest froin 

 the same soil would be smaller unless manure was used to 

 replace the fertility removed in the crop. Thus we see that 

 twenty centuries ago the farmer learned that he must 

 replace fertihty in his soil if he expected to reap abundant 

 harvests. To secure this necessary fertility, he used the 

 manure provided by farm animals; and much was written 

 about the value of the excrement from different kinds of 

 animals, and the preservation of manures. 



In very recent times, artificial fertilizers have come into 

 extensive use. But, in spite of this fact, the natural ma- 

 nures of anmials have been absolutely necessary to keep up 

 the fertiUty of the soil of most regions where high-class 

 farmmg is practiced. There are lands in Europe to-day 

 said to have been cultivated for 2,000 years, that grow great 

 crops, made possible by the use of animal manures This 

 statement may be accepted as a fact, that, except in the case 



♦Cyclopedia of Agriculture, Vol. Ill, 1908, p. 11. 



