250 



SOILS AND PLANT LIFE 



come to be gro'wn more and more in order to keep up the 

 fertility of the soil, it is still true that these crops are as 

 a class difficult to raise and that the percentage of seedings 



which fail is discour- 

 agingh' high. Let us 

 seek out then if we 

 may some of the prin- 

 cipal causes of these 

 failures. 



187. Why Clovers 

 frequently fail. — 



There are at least 

 seven causes of the 

 clover failures which 

 seem to be growing 

 more and more numer- 

 ous throughout the 

 leading grain states : 



(1) The soil has be- 

 come deficient in hme, 

 and because of this 

 may, in fact, be acid. 



(2) The soil is lack- 

 ing in phosphorus. 



(3) The soil is lack- 

 ing in humus. 



(4) The soil does not contain friendly bacteria. 



(5) The nurse crop is not suited to the needs of the young 

 clover. 



(6) The seeding, or sousing, is not properly done. 



(7) Drouths of midsummer or other unfavorable 

 weather conditions may cause the death of the young 

 plants. 



Fig. 112. — Some vines of hairy vetch. 



