﻿528 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1922. 
  

  

  artificial 
  lakes 
  and 
  streams, 
  but 
  the 
  largest 
  changes 
  are 
  those 
  which 
  

   arise 
  from 
  converting 
  a 
  barren 
  and 
  almost 
  uninhabited 
  country 
  into 
  

   one 
  densely 
  populated 
  and 
  with 
  villages 
  or 
  towns 
  at 
  short 
  inter- 
  

   vals, 
  with 
  trees, 
  bird 
  and 
  game 
  refuges 
  around 
  the 
  lakes. 
  The 
  settle- 
  

   ments 
  are 
  connected 
  by 
  highways 
  and 
  railroads; 
  they 
  are 
  supplied 
  

   with 
  electric 
  power, 
  utilized 
  not 
  only 
  in 
  lighting 
  but 
  often 
  in 
  cook- 
  

   ing 
  and 
  heating. 
  The 
  settlers 
  have 
  many 
  of 
  the 
  conveniences 
  which 
  

   are 
  possible 
  in 
  a 
  new 
  community 
  in 
  which 
  cooperation 
  has 
  been 
  

   highly 
  developed. 
  

  

  The 
  social 
  or 
  political 
  changes 
  are 
  profound 
  in 
  that 
  there 
  is 
  

   brought 
  in 
  a 
  population 
  attached 
  to 
  the 
  soil, 
  differing 
  widely 
  from 
  

   the 
  nomadic 
  herdsmen 
  who 
  have 
  previously 
  been 
  in 
  possession, 
  or 
  

   the 
  mining 
  population 
  which 
  comes 
  and 
  goes 
  with 
  the 
  discovery 
  

   and 
  exhaustion 
  of 
  local 
  ore 
  deposits. 
  The 
  shifting 
  population 
  is 
  

   replaced 
  by 
  the 
  most 
  permanent 
  known 
  in 
  history 
  — 
  that 
  is, 
  the 
  tillers 
  

   of 
  the 
  soil 
  who 
  are 
  establishing 
  homes 
  for 
  themselves 
  and 
  future 
  

   generations. 
  

  

  Soil 
  studies. 
  — 
  The 
  works 
  of 
  reclamation, 
  applying 
  water 
  to 
  the 
  

   soil 
  or 
  taking 
  water 
  from 
  it, 
  when 
  followed 
  by 
  the 
  necessary 
  culti- 
  

   vation, 
  result 
  in 
  far-reaching 
  changes 
  in 
  the 
  structure 
  and 
  pro- 
  

   ductivity 
  of 
  the 
  soil. 
  It 
  is 
  now 
  recognized, 
  more 
  than 
  in 
  earlier 
  

   years, 
  that 
  the 
  soil, 
  or 
  that 
  portion 
  which 
  is 
  being 
  tilled, 
  is 
  not 
  

   in 
  a 
  stable 
  or 
  fixed 
  condition, 
  but 
  necessarly 
  undergoes 
  changes 
  

   which 
  are 
  not 
  merely 
  mechanical 
  or 
  limited 
  by 
  the 
  amount 
  of 
  

   water 
  applied 
  or 
  abstracted. 
  Irrigation 
  and 
  drainage 
  result 
  neces- 
  

   sarily 
  in 
  bringing 
  not 
  only 
  water 
  into 
  and 
  out 
  of 
  the 
  soil, 
  but 
  also 
  in 
  

   pumping, 
  in 
  and 
  out, 
  air 
  and 
  various 
  gases. 
  Many 
  of 
  these 
  soil 
  

   changes 
  result 
  in 
  biological 
  developments 
  as 
  well 
  as 
  chemical 
  and 
  

   physical 
  alterations. 
  In 
  one 
  sense 
  the 
  soil 
  is 
  in 
  a 
  continual 
  state 
  

   of 
  change, 
  either 
  for 
  better 
  or 
  worse, 
  as 
  far 
  as 
  plant 
  growth 
  is 
  

   concerned. 
  

  

  Taking 
  an 
  extreme 
  case 
  of 
  soil 
  change, 
  there 
  may 
  be 
  noted 
  that 
  

   of 
  the 
  apparently 
  sandy 
  soil 
  on 
  portions 
  of 
  the 
  Newlands 
  project, 
  in 
  

   Nevada. 
  While 
  this 
  has 
  the 
  structure 
  of 
  a 
  loose 
  sand, 
  and 
  has 
  been 
  

   thus 
  classified, 
  it 
  has 
  been 
  found 
  by 
  experience 
  that 
  under 
  irriga- 
  

   tion 
  it 
  becomes 
  hard 
  and 
  impermeable 
  to 
  water, 
  so 
  that 
  after 
  a 
  few 
  

   years 
  cultivation 
  is 
  no 
  longer 
  practicable. 
  The 
  application, 
  how- 
  

   ever, 
  of 
  certain 
  crude 
  chemicals, 
  such 
  as 
  alum, 
  from 
  natural 
  deposits 
  

   not 
  far 
  distant, 
  tends 
  to 
  increase 
  the 
  permeability 
  of 
  the 
  soil 
  and 
  

   bring 
  it 
  back 
  to 
  a 
  cultivable 
  condition. 
  These 
  changes 
  in 
  soil 
  have 
  

   been 
  discussed 
  by 
  Carl 
  S. 
  Scofield. 
  2 
  

  

  a 
  The 
  Alkali 
  Problem 
  in 
  Irrigation, 
  by 
  Carl 
  S. 
  Seofield, 
  Annual 
  Report 
  of 
  tbe 
  Smith- 
  

   sonian 
  Institution 
  for 
  1921. 
  

  

  