112 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



rock-forming minerals, and liave an even higher content of the essen- 

 tial mineral plant nutrients than well-known and highly productive 

 soils in the United States. 



Important results have been obtained in certain lines of work pur- 

 sued in connection with soil-fertility investigations. The new point 

 of view which has been brought to bear on the problems connected 

 with the fertility of soils has opened up avenues of profitable investi- 

 gation and already forecasted results of great economic importance. 



Whatever adds to the biochemical knowledge of soils advances and 

 broadens our understanding of the complex problems of soil fertility. 

 Important facts have been ascertained in regard to the functional activi- 

 ties of soils, such as oxidation, reduction, etc., and their bearing upon 

 soil fertility determined. The isolation in a pure condition of some of 

 the organic constituents of soils has ma.de possible the correct inter- 

 pretation of soil changes and the discovery of compounds in the soil 

 harmful to crops. This line of research has been especially profit- 

 able this year and has led to the separation of more than twenty 

 definite compounds. Previous to this investigation not a single 

 organic constituent of the soil was known, and the results thus far 

 obtained are very gratifying. There has been studied the effect 

 of these compounds, and of the soils containing them, on plant growth 

 and the ameliorating effect of certain treatments of the soil and the 

 addition of fertilizers. It has been found that fertilizers aid very 

 materially in counteracting the effects of such soil constituents and 

 that certain treatments destroy or remove them entirely. 



THE USE OF SOILS. 



In the twelve years which have elapsed since the initiation of the 

 soil survey the Bureau has accumulated a vast amount of material 

 concerning the soil resources of the United States. Much of this 

 material is scattered through the annual volumes of the Field Oper- 

 ations, but much is in other publications and unpublished records. 



It has been found during the past year that the time has come 

 when it is possible to prepare a comprehensive statement of our 

 soil resources, showing the origin, extent, distribution of, and the 

 uses to which each individual soil type is being placed and can best 

 be placed. A series of reports or monographs is under preparation 

 upon the characteristic soils of each of the soil provinces into which 

 the country is naturally divided. These monographs will constitute 

 an inventory of all of the more important facts concerning the soils 

 of the entire country, the production that is now obtained from 

 them, and the possibilities which they hold for the Nation's future. 

 They will furnish a basis for the future development of the agricul- 

 ture of the American people of a character and breadth of scope 

 never before available to any Nation. 



