ANALYSIS BY THE UNITED STATES BUREAU 151 



tion contains 1170 pounds of total phosphorus in 2 million of dry 

 soil (see Table 15), while 2450 pounds are reported in 2 million 

 pounds of ignited soil of the Wisconsin area (see Table 22). Doctor 

 Fraps finds 480 pounds of acid-soluble phosphorus in 2 million 

 pounds of the Houston clay of Texas- from samples furnished him 

 by the Bureau of Soils, while Table 22 shows 5150 pounds of total 

 phosphorus in 2 million pounds of ignited Houston clay of Alabama. 

 The Texas soil is evidently very deficient in phosphorus, but this 

 is certainly not the case with the Alabama soil, which, it will be 

 seen, outranks in phosphorus content every other soil reported in 

 Table 22. The Bureau of Soils has not reported the ultimate chemi- 

 cal analyses of different samples of the same type soil from different 

 areas, so that it is impossible to make any such comparative study 

 from the Bureau's data alone. 



In the author's opinion, the exact chemical data from which 

 Table 22 is derived, and the careful descriptions given of the type 

 soils analyzed, constitute the most valuable contribution of the 

 United States Bureau of Soils to American agriculture. This 

 absolute invoice of plant food, together with the description of 

 physical properties, crop adaptations, and topographic features, 

 furnishes a basis for the intelligent consideration of possible 

 permanent and profitable systems of agriculture. Actual field 

 experiments, to determine the rate at which the plant food can be 

 made available, are lacking, and no report is made of the nitrogen 

 content of the soils or of the limestone present or required. The 

 percentages of " lime " (CaO) and magnesia (MgO) are given in 

 Bulletin 54, but these signify little or nothing in relation to lime. 

 Even the very acid Marion silt loam of Clay County, Illinois (gray 

 silt loam on tight clay), is reported by the Bureau to contain .56 

 per cent of CaO (5.6 tons in 2 million pounds of soil), whereas it 

 contains neither calcium oxid nor calcium carbonate, the calcium 

 present existing usually in acid silicates. 



In general, the work of the Bureau of Soils has been directed 

 toward a study of crop adaptation, in accordance with a somewhat 

 prevalent notion that every soil is intended to grow some definite 

 crop or crops, and that success will be attained if the proper crop 

 is found for the special soil. While all must recognize that the 

 natural adaptation of soil and crop is an important factor in many 



