﻿36 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  For 
  oats 
  there 
  was 
  needed 
  in 
  1870, 
  according 
  to 
  Risler, 
  a 
  

   quantity 
  of 
  water 
  250 
  times 
  the 
  weight 
  of 
  dry 
  material 
  con- 
  

   tained 
  in 
  the 
  crop. 
  In 
  1871 
  clover 
  transpired 
  263 
  units 
  of 
  

   water 
  to 
  produce 
  one 
  unit 
  of 
  dry 
  substance, 
  and 
  English 
  ray- 
  

   grass 
  545 
  units 
  of 
  water 
  for 
  one 
  unit 
  of 
  hay 
  containing 
  15 
  per 
  

   cent 
  of 
  water. 
  For 
  this 
  last 
  the 
  quantity 
  of 
  water 
  corresponds 
  

   to 
  0.276 
  inch 
  in 
  depth 
  per 
  day. 
  

  

  Risler 
  observed, 
  furthermore, 
  that 
  following 
  rains 
  or 
  wet- 
  

   tings 
  transpiration 
  of 
  plants 
  increases, 
  gradually 
  diminishing 
  

   in 
  proportion 
  as 
  dryness 
  increases, 
  other 
  conditions 
  remaining 
  

   equal. 
  When 
  the 
  water 
  given 
  off 
  by 
  the 
  leaves 
  is 
  less 
  than 
  that 
  

   taken 
  up 
  by 
  the 
  roots, 
  growth 
  is 
  active, 
  while 
  under 
  the 
  contrary 
  

   condition, 
  plants 
  wither. 
  

   ******** 
  

  

  In 
  a 
  general 
  Avay, 
  the 
  consumption 
  of 
  water 
  by 
  plants 
  is 
  

   more 
  regular 
  in 
  clay 
  soils 
  than 
  in 
  sandy. 
  Hellriegel 
  states 
  that 
  

   in 
  a 
  sandy 
  soil 
  plants 
  begin 
  to 
  suffer 
  from 
  drouth 
  when 
  the 
  soil 
  

   does 
  not 
  contain 
  more 
  than 
  2.5 
  per 
  cent 
  moisture. 
  Risler 
  finds 
  

   that 
  the 
  approximate 
  limit 
  for 
  clay 
  soils 
  is 
  10 
  per 
  cent, 
  although 
  

   in 
  clay 
  soil, 
  part 
  of 
  the 
  water 
  escapes 
  absorption 
  by 
  the 
  roots. 
  

  

  Taking 
  as 
  a 
  basis 
  the 
  observations 
  made 
  on 
  the 
  crops 
  raised 
  

   at 
  Caleves, 
  Risler 
  expresses 
  the 
  mean 
  daily 
  consumption 
  of 
  

   water 
  as 
  a 
  depth 
  on 
  the 
  cropped 
  area 
  as 
  follows: 
  

  

  Inches. 
  

  

  Meadow 
  grass 
  requires 
  from 
  0.134 
  to 
  0.267 
  

  

  Oats 
  require 
  from 
  . 
  141 
  to 
  . 
  193 
  

  

  Indian 
  corn 
  requires 
  from 
  . 
  110 
  to 
  . 
  157 
  

  

  Clover 
  requires 
  from 
  . 
  140 
  to 
  

  

  Wheat 
  requires 
  from 
  . 
  106 
  to 
  . 
  110 
  

  

  Rye 
  requires 
  from 
  . 
  091 
  to 
  

  

  Potatoes 
  require 
  from 
  . 
  038 
  to 
  . 
  055 
  

  

  Vineyards 
  require 
  from 
  . 
  035 
  to 
  . 
  031 
  

  

  Oak 
  trees 
  require 
  from 
  . 
  038 
  to 
  . 
  035 
  

  

  Fir 
  trees 
  require 
  from 
  . 
  020 
  to 
  . 
  043 
  

  

  Risler 
  determined 
  the 
  consumption 
  of 
  water 
  on 
  a 
  meadow 
  of 
  

   one 
  hectare 
  (2.47 
  acres) 
  of 
  very 
  thickly 
  turfed 
  English 
  ray-grass 
  

   as 
  281 
  millimeters 
  (11.06 
  inches), 
  amounting 
  to 
  a 
  daily 
  depth 
  of 
  

   0.267 
  inch. 
  This 
  consumption 
  applies 
  to 
  a 
  meadow 
  well 
  provided 
  

   with 
  water 
  during 
  the 
  warmest 
  season 
  of 
  the 
  year. 
  The 
  ex- 
  

   periments 
  showed 
  that 
  on 
  cloudy 
  days 
  evaporation 
  was 
  reduced 
  

   to 
  about 
  one 
  fourth 
  of 
  the 
  mean, 
  that 
  is, 
  to 
  0.069 
  inch 
  per 
  day. 
  

  

  In 
  Switzerland 
  the 
  fields 
  begin 
  to 
  grow 
  green 
  the 
  latter 
  part 
  

   of 
  March, 
  and 
  the 
  hay 
  harvest 
  occurs 
  in 
  June; 
  hence, 
  the 
  growth 
  

   of 
  the 
  plant 
  takes 
  place 
  in 
  April 
  and 
  May. 
  T>he 
  point 
  is 
  brought 
  

  

  