CONSERVATION OF FERTILITY 



327. Manures Necessary for Conservation of Fer- 

 tility. 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 maed, soils are gradually depleted of their fertility. 

 No soil has ever been found that will continue to pro- 

 duce crops without the use of manures. Many prairie 

 soils give large yields for long periods without manur- 

 ing, but they are never able to compete in productive- 

 ness with similar soils that have been systematically 

 cropped and manured. With a fertile soil the decline 

 of fertility is so gradual that it is not observed unless 

 careful records are kept of the yields from year to year. 



328, Use of Crops. The use made of crops whether 

 as food for stock or sold directly from the farm, deter- 

 mines 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 rio restoration of fertility is made, while in the 

 case of stock farming, the manure produced contains 

 fertility in proportion to the food consumed. If good 

 care is taken of the manure, and in place of the grains 

 sold, mill products are purchased and fed, there is no 

 loss and often a gain of fertility. Between these two 

 extremes, exclusive grain farming and stock farming, 

 many different systems of farming are practiced which 

 remove from the soil various amounts of fertility. 



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