PHOSPHATES IN MASSACHUSETTS AGRICULTURE. 137 



binations insoluble in water. Experiment shows that under normal 

 conditions there is but very little loss of phosphoric acid in drainage 

 waters. 



Does it, then, seem probable that in Massachusetts agriculture, as in 

 that of the corn-belt, phosphoric acid is the only mineral element which 

 need be supplied? 



The principal conditions having a bearing upon the tendency in our 

 farm practice may be thus restated : — 



1. In products sold from five to six times as much potash as phos- 

 phoric acid is carried away. 



2. We bring in large amounts of phosphoric acid in purchased feeds. 



3. Potash is far more subject to waste from animal excrements than 

 is phosphoric acid. 



4. The products of our fields, gardens and orchards all require far 

 more potash than phosphoric acid. 



5. In the commercial fertilizers so extensively used far more phosphoric 

 acid than potash has been for years applied to our soils. 



The tendency in our agriculture, therefore, must be to disproportionate 

 consumption of potash and not of phosphoric acid. 



If, however, the stock of phosphoric acid in our soils is extremely small, 

 — far less than the stock of potash, — then it may nevertheless be true 

 that phosphoric acid rather than potash is the principal fertihzer require- 

 ment in our agriculture. 



A study of the results of such analyses of our soils as have been made 

 is essential co the formation of a conclusion upon this point. 



Composition of Massachusetts Soils. 



This experiment station has published the results of analj'ses of 194 

 soil samples ^ taken in tliis State. These samples have come from 79 

 different towns and represent practically all our leading soil types. All 

 the counties of the State except Dukes and Nantucket — the island 

 counties — ai-e represented. 



The analyses reported have been made by the methods recommended 

 by the American Association of Official Agricultural Chemists. These 

 methods do not show the totals of any of the plant-food elements except 

 nitrogen, but only the proportion which is dissolved in an acid of definite 

 strength used at a definite temperature for a definite length of time. 

 The results are beheved to represent at least the percentages likely to 

 become available within a generation. The table shows the average 

 results by counties and for the entire State. 



' See twenty-third anniial report, Massachusetts Agricultural Experiment Station, p. 339. 



