32 



air for that element. Growing clover upon manures, therefore, is not the 

 best economy. Moreover, it is important to point out that the grasses 

 with which clover is most generally grown are greatly invigorated by 

 heavy dressings of manure. A strong, rank growth of the timothy and 

 redtop will tend to crowd out the clover. Fine crops of hay maj'- be 

 produced, but it will not be clover hay, nor rich in clover. The writer 

 would not be understood as urging that manure should never be used 

 on land which is being prepared for clover, although he would strongly 

 advise against top-dressing clover with manure. On soil which is 

 naturally poor in nitrogen, manure may wisel)' be used in moderate 

 amounts for crops preceding clover. Heavy dressings would be a mis- 

 take. It is far better to use the manure in only moderate or small 

 amounts, and to use it in connection with materials which will supply 

 lime, phosphates and potash. 



3. The Supply of the Mineral Elements of Plant Food should he Lib- 

 eral. — 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 unlimited. The more of this nitrogen we can 

 gather in the crop and in its roots and stubble the better. In a certain 

 sense, this trapped atmospheric nitrogen is so much clear gain. In 

 considering this point it must be remembered that the clover plant 

 like other plants must take the different food elements in a certain 

 balanced proportion. Though the nitrogen the clovers need is practi- 

 cally 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 preparing 

 for clover or in top-dressing for clover should be to supply the phos- 

 phates, potash salts, lime and possibly magnesia 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 Co-operation of Bacteria is essential. — One of the most im- 

 portant discoveries of recent times is the now generally 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 ellip- 

 tical 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 condi- 

 tions 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 veriest dust of the dust. As might be sup- 

 posed, therefore, they appear to be very widely and freely disseminated, 

 antl probably tlirough the air. The slightest currents of air must carry 

 them. The dust from a freshly turned clover sod must contain count- 

 less millions of them. In certain quarters it has been urged that fail- 

 ures to produce good clover are frequently due to the absence of suitable 

 bacteria, or to their presence in insufficient numbers. Certain experi- 

 ments with sterilized soils in Amherst indicate to the writer that clover 

 bacteria are everywhere, and it is not his belief that failures to produce 

 satisfactory croi)s of clover in this State can often, if indeed they can 

 ever, be attributed to the cause under consideration. The writer has 

 never seen a case where if a soil be brought into proper condition as to 



