Nm. 6. DEPARTMENT OF AGItlCCLTCRE. tiH 



and l}i;jt iiiiiili of our daily practice is fithcr based iiijoii pie-cou- 

 ccivcd ideas or- been moulded by such informalion as has beeu 

 given out which would serve the iuterest of fertilizer numufacturers. 

 It is certaiij that a careful study of the results of the experiments 

 given in the preceding pages will make it evident to all that there 

 is more need of a careful study of the character of land to which 

 the phosphate is to be applied and then to use the form of phosphoric 

 acid and other accessory measur(-s which will gain the desired results 

 most economical! V. 



REVIEW OE THE RESULTS OF THE EXPERIMENTS. 



All of the experiments which have t>een conducted uj^on the use of 

 I)hosphoric acid in agriculture have given results which seem to 

 warrant the general statement that much of the practice aow follow- 

 ed in the use of phosphates is not founded upon facts; but are pro- 

 bably backed either by the tradition and statements gathered from 

 the customs of our forefathers or promulgated by the teachings of 

 the commercial w^orld. The latter, in many cases, are much colored 

 for the sake of self preservation and financial gain. 



There is no doubt hnt that the first step in the economical use of 

 I-'hosphates is to imitate nature and endeavor to keep the soil well 

 supplied with organic matter; for it is only by such means that the 

 phosphates contained in the soil naturally and those applied artifi- 

 cially can be fully utilized by the cultivated crops. 



It is very evident from all the tests cited that some crops, particu- 

 larly the turnip family, have a greater ability than others to use 

 crude or insoluble jdiosphates and these experiments would certainly 

 teach that the aim should be to employ such crops for rendering in- 

 soluble phosphates available and by such a practice save much that 

 is now being spent for sulphuric acid and the cost of manufacturing 

 the soluble phosphates. 



The experiments, in most instances, show that the presence of cor- 

 bonate of lime is of considerable advantage in increasing the avail- 

 ability of phosphates. 



■ Some of the tests show that the iron and alumina phosphates are 

 much more valuable as plant foods than is generally considered, in 

 fact under some circumstances they seem to be as soluble and even 

 superior to lime phosphates. 



In regard to the so-called available phosphoric acid of commercial 

 fertilizers, the results all point to the fact that there is no difference 

 in it depending upon its source; that is. a pound of available phos- 



