A(;iiicrLT»'nAi. appropriatiox biij*, uri*. 275 



Soil 111 tin- iii\ c-ti^Miioii i>l •xiil phynicM Htu<Ii(f< an- iiunl*- <»| the ph>xi<al 



<-hani< ! of thf soil in tlicir rflalimi to th«' optiiiiiini nuil i-onilitioiin (or planl 



^Towtii OiH- of th)' iiii|>or(aiit Mludii'H in thiH coiitiiTtion ix that of lh<* iti(M-haiiii-ul 

 or f«'Xtimil r-onij)o.Mition of the ooil. 



Ilfvi'iitly a >rn>at a<lvan<'<» ha*< In-^-n iimWc in th<- ntinly of th«' |)h\^iral roinjjonition 

 (»f the soil in the n>rojfnition of the vnry important r<M«' which .'«>il <olloi(|n play in it. 

 A nrw nn'tho(| i> l>cinK Icst«'<l out in whi<h arcount is lukcu of iIm- iitiunlitv r>f cullnid 

 prfS4'nt Th«' work hits shown that nnuh of th<' nuili'riul fornuTl 1 



and silt j:roups ri^:htfully ln>lon>;s in the Kroup of colloids The f' -, 



ao-onlinf; to this new method, will cxpri'ss the perr-rtitaKi' of colloid j>r(>(M-ni in the 

 soil. This will Iw of imi)ortan<T. hccjiiise it ha.H lon^ U-cn rerotjni/.e<i that the phyH- 

 i«-al londition stiitalile fos tillage or other soil o|MTalions is rIo*<4'|y n-lated lo the 

 rolloitl content. 



KxpiTiincnts have shown that the hearing strenjfth of soiIh varies with thf Chanel's 

 in the relativ*- amount of <olloid and olln-r >(ra<les of soil material, su( h as silt and 

 sanci. pp'Sfnt Work is pn)c«HHlinK at prer^ent with a view to c^ftabliiihing the rela- 

 tions h«'tw<KMi the comp«wition uiuj variations in hearing streiiKth. 



In addition t4> the funtlamenlal rest-arches on the physical condition of the <«oi!, 

 n)utinc analyses of mechanical comiM>sition are carried out on samples of Sfiil collecte<l 

 hy the .^oi I Survey in order to assist them in determining the claHsilic-ation of the 

 various .soil typ-s. .\side from the work done lor the soil survey there is considerable 

 demanil for work by other orpinizations, such a^ the Geological .Survey, the Miflsisflippi 

 River I.evee CommisKion, the lUireau of I'liblic Roads, and other agencies Cf)ncernecl 

 with the use of soil material in structural work. The demand from these various 

 sounvs show the wide applicability of mechanical analysis to the practical i)roblem8 

 in relat.i«m to the soil. 



In this division there are designed and constructed sjjecial ])iece8 of apparatus 

 re(|uired lor the projier pn)secution of the investigations along .soil lines and which 

 have wide api)licability in the study of .>*oil problems. One such in.strument designed, 

 namely, the electrical bridge, h;u» been adopted for use in studying alkali lands, not 

 only in this country- but in Egypt and other alkali regions. 



The pivsi y<'ar has been exceedingly fruitful in bringing together the results achieved 

 by the lUireau during it.s (|uarter centur>' of existence into a modem concept of the 

 .•<oiI. its various functional activities, giving us a comprehensive view of the soil, which 

 has never been clearly understood before. 



FOR CHE.MICAL IXVESTKJATIOXS OF SOIL TYPE.S, ETC. 



Doctor Whitney. The work of the cliemical inve.stiojation.s has 

 progressed very satisfactorily. I feel that in the last year or in the 

 last two years, with the discoveries and investigations Mfe have made 

 of the soil colloiils. we have a concept of the soil we have never had 

 before. We have completed the separation of the functional activities 

 of the soil into its ctmiponent parts. Heretofore the world has been 

 working along different lines of soil investigation, on chemical lines, 

 on physical lines, and on practical lines, and we have been pushing 

 each (if these lines along as far as we can. It has only been possible, 

 since our work on the soil colloids, to bring them all together and 

 present a fair picture of the functional activities of the soil as a whole. 

 We know now, through our investigations, the differences in the 

 functional activities in this soil [indicating] which is a truck .soil and 

 not adapted tt) general farming, and the functional activities of this 

 other soil [indicating] which is the strongest type of agricultural soil 

 in the country — that is, for general agriculture — and while there will 

 alwavs be a great deal of work to do to find the spe<'ific faults we know, 

 in a general way, why these soil types differ. 



Mr. Anderson. Can you tell us wh\' one soil is best adapted to 

 truck while another soil is be.st adapted to grains ? 



Doctor Whitney. Yes, sir. We are understanding those things 

 in our present concept of soils. We have brought all of these things 

 together, the physical properties, the chemical properties, and the 



