USE OF PHOSPHORUS IN DIFFERENT FORMS 299 



On the other hand, this crude material, when properly treated with sulfuric 

 acid and converted into acid phosphate, to be used either as straight acid 

 phosphate or in mixed fertilizers, becomes a source of available plant food of 

 greatest value. Raw rock phosphate, as mined and sold by certain operators, 

 does not contain plant food immediately available to growing crops. It is only 

 by proper handling and treatment with sulfuric acid that this material is con- 

 verted into fertilizer furnishing plant food available to various crops and soils. 



Reputable fertilizer manufacturers decry the use of raw rock phosphate as 

 a fertilizer, knowing that it will NOT prove satisfactory, as borne out by exten- 

 sive experiments of the world's best agriculturists. They have gone on record 

 against its use, and any lack of results on the part of those using this material 

 should not vitiate against the use of commercial fertilizers rightly prepared, 

 furnishing available, nourishing plant food for all crops. 



(Signed) THE NATIONAL FERTILIZER ASSOCIATION. 



The author feels that no further comment is necessary regarding 

 this statement from the National Fertilizer Association. The 

 facts are presented in very complete form in the preceding pages, 

 and the reader must draw his own conclusions. For other illustra- 

 tions of the possibility of erroneous conclusions being drawn by 

 such German investigators as advance theories or reach conclu- 

 sions without sufficient facts, reference may be made to Chapter 

 31, and also to Sir Henry Gilbert's very interesting and complete 

 discussion 1 of the sources of fat in the animal body, based upon 

 Rothamsted investigations in which 327 different animals were 

 dissected, 10 different selected carcasses having been subjected to 

 chemical analysis, following the analysis of the food stuffs provided 

 during long feeding periods. 



1 Pages 231 to 282, Bulletin 22, Office of Experiment Stations, United States 

 Department of Agriculture, "Agricultural Investigations at Rothamsted dur- 

 ing a period of Fifty Years," containing a series of six lectures delivered in 

 America in 1893 by Sir Joseph Henry Gilbert, under the provisions of the Lawes 

 Agricultural Trust. 



