182 
Production  of  Lemon-Grass  Oil.    {  Am.  jour,  pharm. 
J  1       April,  1917. 
nitrogen,  5  per  cent,  potash,  and  8  per  cent,  phosphoric  acid,  applied 
at  the  rate  of  600  pounds  to  the  acre,  has  given  the  best  results  with 
the  least  cost.  On  soils  of  higher  fertility  a  smaller  quantity  could 
be  used.  Although  the  use  of  larger  quantities  of  fertilizers  will 
give  a  heavier  growth,  it  is  by  no  means  certain  that  the  additional 
cost  will  be  met  by  the  increase  in  the  crop. 
As  soon  as  the  plants  have  become  well  established  in  the  field 
the  fertilizer  should  be  given  as  a  side  application  and  well  worked  in 
at  the  first  cultivation.  Cultivation  should  be  frequent  throughout 
the  spring,  to  conserve  the  soil  moisture,  and  throughout  the  summer 
all  weeds  should  be  kept  down,  as  a  few  ill-smelling  weeds  in  the 
crop  at  harvest  time  will  greatly  injure  the  odor  of  the  oil.  After 
the  first  year,  only  slight  cultivation  is  needed,  since  after  it  is  well 
established  lemon  grass  tends  to  retard  weed  growth. 
HARVESTING. 
The  first  cutting  should  be  made  four  or  five  months  after 
planting,  at  which  time  the  plants  should  be  from  2.y2  to  3  feet  high 
and  the  bunches  from  8  to  10  inches  in  diameter.  Although  the 
plants  will  continue  to  grow  throughout  the  summer,  it  has  been 
found  that  after  a  certain  size  has  been  reached  the  increase  in 
weight  is  less  rapid ;  hence,  it  is  more  profitable  to  harvest  the  crop 
at  the  time  stated  and  allow  a  new  growth  to  develop.  In  the  early 
fall  of  the  first  year  a  second  cutting  can  be  secured.  After  the  first 
year  the  growth  in  the  spring  is  more  rapid  and  three  harvests  a 
year  can  be  obtained.  Harvesting  can  be  accomplished  by  the  use 
of  a  mowing  machine  so  adjusted  as  to  cut  the  plants  about  8  inches 
above  the  ground.  The  cut  material  can  be  raked  up  with  a  horse- 
rake  run  crosswise  of  the  rows. 
In  order  to  determine  the  proper  stage  and  height  at  which  the 
plants  should  be  cut  to  produce  the  best  yield  and  quality  of  oil,  a 
number  of  tests  were  made,  covering  several  years.  In  1908  the 
plants  were  cut  when  they  were  2  feet  high.  They  were  then  tied 
in  bundles,  the  bundles  cut  into  three  8-inch  lengths,  and  each  portion 
distilled  separately.  The  yield  of  oil  obtained  from  each  portion, 
together  with  the  citral  content  of  the  oils,  is  shown  in  Table  I. 
From  these  results,  which  are  borne  out  by  additional  data  ob- 
tained in  succeeding  years,  the  conclusion  is  evident  that  close  cutting 
will  not  be  profitable,  because  of  the  low  oil  content  in  the  lower 
portion  of  the  plant. 
