636 APPENDIX 



stated, however, that, of the 286 samples of soil reported below, 129 

 contained an amount of acid-soluble calcium which if present as car- 

 bonate would represent 10 tons or more of limestone per acre in the 

 plowed soil, and of these about 60 apparently contained more than 50 

 tons per acre of calcium carbonate, thus suggesting the British farmer's 

 common appreciation of the importance of having limestone in the soil. 



The following table shows the phosphorus reported for each of these 

 286 samples of soil, and the data certainly indicate that Liebig's ac- 

 count of the tendency (even then apparent) toward the accumulation 

 of phosphorus in British soil was well founded. As a general average 

 of all analyses, it will be seen that the soil of England now contains about 

 twice as much phosphorus as the most common Illinois corn-belt land 

 (brown silt loam), three times as much as the ordinary wheat-belt soil 

 of southern Illinois (gray silt loam on tight clay), and from four to 

 fifteen times as much as the depleted or abandoned lands of the Atlantic 

 Coastal Plain (such as the Leonardtown loam and Norfolk loam, the 

 latter belonging to a series of thirteen soil types already represented by 

 surveyed areas aggregating about 10 million acres, of which, however, 

 soil analyses have been reported for only two types, as shown in Table 

 22, page 138). 



The amount of phosphorus in 2 million pounds of surface soil varies 

 in the Gault soils of Kent County from 330 to 2210 pounds; in the chalk 

 soils from 820 (Kent County) to 6800 pounds (Dorset County) ; in the 

 Kimmeridge clay from 810 pounds (Cambridgeshire) to 7760 pounds 

 (Dorset County); and in the London clay from 460 pounds (Surrey 

 County) to 4100 pounds (Dorset County). Contrasted with these vari- 

 ations, the records 1 of analysis of 555 samples of Illinois soils, in- 

 cluding surface, subsurface, and subsoil, show an extreme variation from 

 540 to 2780 pounds of phosphorus in 2 million pounds of soil, the late 

 Wisconsin yellow-gray silt loam varying from 540 pounds in 2 million 

 of the subsurface to 900 pounds in the surface, and the early Wisconsin 

 black clay loam varying from 980 pounds in 2 million of the subsoil to 

 2780 in the surface. 



1 University of Illinois Agricultural Experiment Station Bulletin 123 (1908), pp. 

 262-294. 



