b FEEDING FARM ANIMALS 



They do not add to the humus in the soil, except 

 through increase which they cause in root production in 

 the crops grown. The presence of humus is necessary to 

 insure the most efficient action possible from the ferti- 

 lizers, hence, in the absence of long continued applications 

 of farmyard manure or of buried crops, they do not stimu- 

 late growth as they otherwise would. 



When the crops grown are sold and shipped away from 

 the farm, all the fertility which they contain of course 

 goes with them. When these are fed to live stock and the 

 fertilizer resulting is put back upon the land, it is possi- 

 ble in this way to restore to the land from, say 85 to 90 

 per cent of the fertilizing elements that were taken from 

 it. The keeping of the live stock also necessitates, more or 

 less, the growing of legumes to be fed to them, a process 

 which tends to increase the nitrogen content in the soil, 

 since these crops deposit in the soil more nitrogen 

 gathered from the air than is sold in the meat, milk or 

 wool made from feeding them. 



In some instances, the fertility may be sufficiently main- 

 tained through keeping live stock only, at 1 east for a long 

 term of years. In other instances it may be maintained 

 through the application of commercial fertilizers only. 

 The former finds illustration in the rich lands of the 

 prairie states, the latter in the grass producing lands of 

 the alluvial river bottom lands of the eastern states. On 

 ordinary soils, however, fertility may be most evenly 

 maintained by the moderate and judicious application of 

 commercial fertilizers in conjunction with the judicious 

 maintenance of live stock . 



The equilibrium of fertility can thus be maintained and 

 increased. The limit to such increase is the capacity and de- 

 sire of those who cultivate the soil. With increase in fertility, 

 the cost of growing crops will decrease, and there will be a 

 proportionate increase in profits. To maintain such equilib- 

 rium in fertility is probably the most important question per- 

 taining to the agriculture of this country. 



