CONSERVATION OF FERTILITY 285 



9. -Plan a rotation for a market milk farm of 90 acres. One hun- 

 dred head of stock are kept and mostly mill feed purchased. 

 Soiling crops are to be provided ; corn silage and clover are the 

 main coarse fodders. 



CONSERVATION OF FERTILITY 



342. Manures Necessary for Conservation of Fertility. 

 In order to conserve the fertility of the soil, not only 

 must a systematic rotation be practiced, but a proper 

 use must be made of the crops produced. When crops 

 are sold from the farm and no restoration is made, soils 

 are gradually depleted of their fertility. No soil has 

 ever been found that will continue to produce crops 

 without the use of manures. Many prairie soils give 

 large yields for long periods without manuring, but 

 they are never able to compete in productiveness with 

 similar soils that have been systematically cropped and 

 manured. With a fertile soil the decline in fertility is 

 so gradual that it is not observed unless careful records 

 are kept of the yields from year to year. 



343. Use of Crops. The use made of crops whether 

 as food for stock or sold directly from the farm de- 

 termines the future crop-producing power of the soil. 

 With different systems of farming different uses are 

 made of crops. When exclusive grain farming is fol- 

 lowed there is no restoration of fertility, while in the 

 case of stock farming, the manure produced contains 

 fertility in proportion to the food consumed. If good 



