214 SOILS AND FERTILIZERS 



Corn. Phosphoric acid first, then nitrogen and 

 potash. 



Potatoes. General manuring, re-enforced with pot- 

 ash. 



Ma ngels. N i tr ogen . 



Turnips. Phosphoric acid. 



Clover. Lime and potash. 



Timothy. General manuring. 



292. Commercial Fertilizers and Farm Manures. 

 Commercial fertilizers should not replace farm 

 manures, but simply re-enforce them. Although 

 commercial fertilizers are called complete manures, 

 they fail to supply organic matter. It is more im- 

 portant in some soils than in others, that the organic 

 matter be maintained, because in some soils the 

 organic matter takes a more important part in crop 

 production than does the food applied in commercial 

 forms. When a rich prairie soil is reduced by grain 

 cropping and is allowed to return to pasture, heavier 

 yields of grain are afterwards obtained than from sim- 

 ilar soils which have received only applications of com- 

 mercial fertilizers. This is due to the action of the 

 humus in the soil. At the Canadian Dominion Ex- 

 perimental farms where comparative trials have been 

 made for fourteen years with farm manures and com- 

 mercial fertilizers, it has been found that farm 

 manures even on new lands give better results than 

 commercial fertilizers for production of wheat and 

 corn. 



