58 



3. The Supply of the Minei-al Elements of Plant Food 

 should he Liheral. — We should not forget, in considering the 

 best means of growing clover, that the stock of nitrogen in the 

 air from which it is capable of drawing is practically nnlim- 

 itod. The more of this nitrogen we can gather in the crop 

 and in its roots and stnbble, the better. In a certain sense, 

 this trapped atmospheric nitrogen is so mnch clear gain. In 

 considering this point, it mnst be remembered that the clover 

 plant, like other plants, mnst take the different food elements 

 in a certain balanced proportion. Thongh the nitrogen the 

 clovers need is practically unlimited in amount, they cannot 

 make a heavy growth unless provided with a great abundance 

 of the elements which they must take from the soil. It is 

 clearly unwise to lessen our chances for gathering the valuable 

 element nitrogen from the air through failure to supply the 

 soil elements in adequate amounts. The rule, then, in pre- 

 paring for clover or in top-dressing for clover should be to 

 supply the phosphates, potash salts, lime and possiljly mag- 

 nesia in great abundance. With these present in abundance, 

 and with a soil of such a character that it will furnish suitable 

 conditions and supply the needed moisture at critical times, 

 enormous crops of clover may be produced. 



4. The C o-operation of Bacteria is essential. — One of the 

 most important discoveries of recent times is the now gener- 

 ally known fact that the presence of certain bacteria living in 

 symbiotic relations with the clovers and other members of the 

 clover family, and found in nodules on their roots, is essential 

 in order that these plants may draw upon the air for nitrogen. 

 The nodules which in the case of clovers indicate the presence 

 of suitable bacteria are whitish, more or less elliptical bodies, 

 of about the size of the head of a small pin. These grow 

 singly or in small clusters, mainly on the smaller roots. They 

 can be readily found by taking up clover plants grown under 

 proper conditions, with care not to break off too many of the 

 small roots. Bacteria, as is generally understood, are plants. 

 They are very minute. The bacteria themselves are the veri- 

 est dust of the dust. As might be supposed, therefore, they 

 appear to be very widely and freely disseminated, and prob- 



