II i I KKS >! sriSMlTTAI.. 



WASHINGTON, ]>. C., June 20, 1004. 



SIB: In conducing invoii^ninns along the lines of those 

 reported in the bulletins 011 "The Amounts of Plant Food Re- 

 coverable from Field Soils with Distilled \V:it<-r," and on the 

 "Relation of Crop Yields to the Amounts of Water-Soluble 

 Plant Food Materials Recovered from Soils/' the power of 

 soils to absorb plant food materials from, solutions, when 

 brought in contact with them, could not be omitted from con- 

 sideration ; neither could the re-solution of such absorbed mater- 

 ials be ignored. Moreover, since it has been long (recognized 

 that the influence of both good soil management and bad soil 

 management is cumulative in its effects upon, soils to a marked 

 degree, while the reasons for these tendencies are not suffi.- 

 ciently understood, it is of fundamental importance to ascertain 

 whether the productive capacities of soils are, in. any essential 

 way, related to their absorptive and retentive powers over the 

 essential plant food materials ; and whether good soil manage- 

 ment may not result in clothing the soil skeleton with heavier 

 and heavier accumulations of these miaterials while the reverse 

 tendency may not be associated with poor soil management. 



The absorption studies submitted herewith, were made chiefly 

 upon the 8 soil types which have contributed a large share of the 

 data of the two former investigations whose results have been 

 submitted, and they have, therefore, a value they would not 

 otherwise possess. We have also incorporated so much of the 

 results of investigations along these lines, made between. 1845 

 and 1865, as will serve to indicate the nature of the results and 

 the importance attached to this subject at that time. 



The determinations for this work have been made chiefly by 

 Mr. J. O. Belz, A. H. Snyder, J. W. kelson, W T . C. Palmer, 

 F. R. Pember, and J. C. Hogenson, and the solutions used were 

 prepared by Dr. Schreinr r. 



F. H. KING, 



Chief of the Division of Soil Management. 

 PROF. MILTON WHITNEY, 



Chief of the Bureau of Soils. 



