36 



dred poiinds per acre of soil from a field where the nodules are found 

 to be abundant on the clover, or by the use of a special culture prepared 

 in the United States Department of Agriculture It is not believed, how- 

 ever, that it will often be found essential to supply these bacteria. 

 Clover has been so long and so generally grown in this section that 

 these bacteria are practically everywhere abundant ; and the nodules 

 will develop upon the roots of clover in practically all situations, pro- 

 vided the conditions essential to the life and activity of the bacteria 

 (which are, in brief good drainage, thorough tillage and aeration and 

 freedom from free acid) exist. The supply of nitrogen in the air which 

 the clover bacteria under the right conditions bring within the reach of 

 the crop is practically unlimited. It pays, therefore, to make the supply 

 of the elements which clover must take from the soil exceedingly abun- 

 dant, and among the elements needed potash is one of the most impor- 

 tant. In preparation for clover it is believed that the ajjplication of 

 from 200 to 300 poiiuds of a high-grade potash salt, or double that 

 quantity of the low-grade sulfate of potash, will in most cases be use- 

 ful. 



If manure is carefully saved and applied in moderate amounts, clover 

 often does well ; but if any considerable proportion of the urine of the 

 manure has been suffered to waste, or if the manure has been exposed 

 to the leaching action of rainfall, there will be a deficiency of potash, 

 which is found chiefiy in the urine, and which, being soluble, is easily 

 washed out. If, then, it be desired to bring land on which manure is 

 used for previous crops into good condition for producing a hay crop 

 rich in clover, it will usually be best to supplement the manure by 

 means of an application of potash. From 125 to 150 pounds of a high- 

 grade potash salt per acre, applied in connection with manure to the 

 previous crop, will ahuost invariably largely increase the proportion of 

 clover in the hay crop when the land is seeded. If fertilizers alone are 

 used for the preceding hoed crops, these must be rich in potash if clover 

 is to thrive when the land is seeded. 



Upon the college farm at Amherst we have for about thirteen years 

 applied potash to two plots of one-quarter acre each at the rate of about 

 250 230unds per acre of a high-grade potash salt. To two other plots 

 the same salt has been applied at the rate of about 150 pounds per acre. 

 When this land is seeded, the hay crop where the larger amount of 

 potash is used is considerably larger and contains a much greater pro- 

 portion of clover than where the smaller quantity of potash is used. In 

 191 '2 the larger application of i^otash gave a yield at the rate of 6,772 

 pounds per acre ; the smaller application of potash yielded at the rate 

 of 6,252 ])Ounds per acre. For a full understanding of the conditions in 

 this experiment it should be further stated that the quantity of nitrogen 

 applied to the two sets of plots is substantially the same, while the plots 

 receiving the lighter application of potash annually receive an applica^ 

 tion of acid phosphate at the rate of about 1,100 pounds per acre, and the 

 plots receiving the larger amount of potash acid phosphate at the rate 

 of about 200 pounds per acre. The fertilizer applied where the lesser 

 amount of potash is used is substantially the same in its composition as 



