236 MASS. EXPERIMENT STATION BULLETIN 194. 



The different samples show a marked uniformity in the percentage of 

 constituents, which are low with the exception of phosphoric acid in the 

 surface soil. This marked proportion of phosphoric acid in the surface 

 soil is not due to the liberal application of phosphatic fertilizers, however. 

 Assuming the surface soil of an acre to weigh 2,000,000 pounds, there are 

 5,000 pounds of phosphoric acid contained in it. The fertilizers applied 

 to an acre contained approximately 350 pounds. The vegetable matter 

 in the surface soil is probably the means by which the phosphoric acid, 

 lime and nitrogen are accumulated in the surface layer when compared 

 with the lower depths. 



There is observable a small difference in the proportion of fine soil in 

 the sample from the southeast quarter, which may in part account for 

 a poorer yield of asparagus from the plots on that area. 



The arrangement of the plots is shown in the plan on page 235, and the 

 kinds of fertilizers and the yearly yields of asparagus are given in Table II. 



Table II. — Yields -per Plot (Pounds). 



