PHOSPHATES IN MASSACHUSETTS AGRICULTURE. 133 



INTRODUCTION. 



During the last few years the system in the use of fertilizers, and more 

 particularly the practice of depending upon fine-ground rock phosphate, 

 so strongly advocated by Dr. Cyril G. Hopkins and some others, and 

 based largely upon experimental results obtained by Dr. Hopkins in 

 Illinois, have been prominently advocated in some of our agricultural 

 papers for adoption under Massachusetts conditions. At the present 

 time a company interested in the sale of fine-ground natural phosphate 

 is carrying on an active propaganda which aims to convince our farmers, 

 fruit-growers and gardeners that the chief fertilizer requirement of their 

 soils is phosphoric acid, and that fine-ground natural rock phosphate is 

 the material best adapted to their needs. The literature sent out by tliis 

 company is being distributed everywhere. The conclusions urged are 

 supported by numerous quotations, figures and illustrations drawn chiefly 

 from the publications of experiment stations in the great central valley 

 — the corn-belt • — • of the United States. This matter is so marshalled 

 and presented that the argument seems likely to produce a strong im- 

 pression; it may carry conviction to many minds. 



It is of the utmost importance to our agriculture that the extent to 

 which the teacliings of Dr. Hopkins (the father of the sj^stem) are appli- 

 cable under Massachusetts conditions should be known. If he be right, 

 then certainly our farmers are buying unnecessary fertilizer elements, 

 and needlessly paying the fertilizer manufacturers to render the phos- 

 phoric acid of the rock phosphates soluble and available. The adoption 

 here of the Hopkins system, if sound, must mean a more profitable agri- 

 culture. 



It seems, therefore, highly important that the whole question should 

 be most carefully studied. Local conditions must be compared with 

 corn-belt conditions; the results of local experiments must be presented 

 and studied. It is well known that practice must usually vary with 

 locality. A practice wise in one section is often most unwise in another 

 where conditions are different. 



The general features of the Hopkins system are stated on page 159 

 of his book on "Soil Fertility and Permanent Agriculture," from which 

 the following quotation is taken : — 



For practically all of the normal soils of the United States, and especially for those 

 of the Central states, there are only three constituents that must be supplied in 

 order to adopt systems of farming that, if continued, will increase, or at least per- 

 manently maintain, the productive power of the soil. These are limestone, phos- 

 phorus and organic 7natter. The limestone must be used to correct acidity where it 

 now exists or where it may develop. The phosphorus is needed solely for its 

 plant-food value. The supply of organic matter must be renewed to provide 

 nitrogen from its decomposition and to make available the potassium and other 

 essential elements contained in the soil in abundance, as well as to liberate phos- 

 phorus from the raw mineral phosphate naturally contained in or applied to the 

 soil. 



