138 THE GRASSES OF TENNESSEE. 



The clover roots bring this ammonia or nitrogen to the 

 surface, and on their decay these nitrogenous matters are 

 converted into nitrates in which the wheat plant finds a 

 most congenial food. In addition to this, the leaves formed 

 by clover contain a large amount of nitrogenous matter, and 

 these are dropped upon the surface, increasing the amount 

 of nitrogen available for wheat or other crops. 



A synopsis of Professor Voelcker's article on the causes 

 of the benefit of clover as a preparatory crop for wheat, 

 cannot fail to be interesting. Prof. Voelcker, writing in 

 1869, says: 



It is well known to most practical farmers that if they can succeed 

 in growing a good crop of clover they are almost certain to get a good, 

 paying crop of wheat. You see how all agricultural matters depend 

 upon each other. I have come to the conclusion that the very best 

 preparation the very best manure, if you will allow me to thus ex- 

 press myself, is a good crop of clover. Now, at first sight, nothing 

 seems more contradictory than to say you can remove a very large 

 quantity of both mineral and organic food from the soil and yet make 

 it more productive, as in the case of clover. Nevertheless, it is a fact 

 the larger the amount of mineral matter you remove in a crop of clover, 

 and the larger the amount of nitrogen which is carried off in clover hay 

 the richer the land becomes. Now, here is really a strange chemical 

 anomoly which cannot be discarded and invites our investigation, and 

 it is an investigation which has occupied my attention, I may say, for 

 more than ten years. 



This clover investigation has very much interested me, but only 

 during the last season have I been able to bring it to anything like com- 

 pletion, so as thoroughly to explain the strange anomoly that is pre- 

 sented to us in the growth of clover as a preparatory crop for wheat. 

 The explanation is very simple though puzzling when you know not 

 the chemical points that are involved in the investigation. I cannot 

 deny myself the gratification of showing you a few figures that in a 

 thoroughly chemical point of view, show that clover is the most ex- 

 haustive crop that you can possibly grow, while in a thorough practical 

 point of view it is the most restorative crop and the best preparative 

 crop for wheat that you can possibly grow. 



Now if we examine what is taken from the land in the shape of 

 clover, we shall find that, assuming an acre of land to four tons of 

 clover hay, these four tons of clover hay will remove 672 pounds of 

 mineral constituents, and not less than 224 pounds of nitrogen which 



