Vol.  XV.] 
COLOMBO, 
NITROGEMOUS  MAF^URES  ARD 
THEIR  EFFECT. 
HERE  are  ten  elements  abso- 
lutely essential  for  the  produc- 
tion of  plants.  These  are 
nitrogen,  hydrogen,  oxygc-n, 
carbouj  sulphur,  phosphorus, 
potassium,  calcium,  magne- 
sium, and  iron.  It  is  to  the 
first-named  element  (uiirogen) 
that  I wish  to  call  altoution,  p.ud  I will  endeavour  to 
show  how  important  it  is  that  wo  should  beoomo  well 
acquainted  with  it.  Nitrogen  was  discovered  by  Ru- 
therford hi  1772,  aud  is  a aolourle.ss  inert  gas,  slightly 
soluble  in  water.  It  occurs  free  in  the  atmosphere,  of 
which  it  constitutes  7!)  per  cent,  or  II  lb.  to  every 
inch  of  the  earth’s  surface.  The  nitrogen  and  oxygen 
of  the  atmosphere  combine  under  the  iuliuence  of 
electric  discharges,  nitrous  acid  being  formed,  which 
is  converted  into  nitric  acid  by  the  action  of  ozone 
or  pero.xido  of  hydrogen.  It  forms  several  com- 
pounds useful  to  those  engaged  in  horticultural  and 
agricultural  pursuits.  Ammonia  is  a compound  of 
nitrogen  aud  hydrogen. 
Owing  to  tlie  complicated  changes  of  nitrogen 
in  the  soil,  it  is  of  the  utmost  importance  that  we 
should  study  the  natural  sources  of  its  loss  and 
gain  there  if  wo  wish  to  become  we  1 acquainted 
with  the  difficult  question  of  soil  fertility.  How 
does  the  soil  obt.niu  nitrogen  in  a natural  way  ? 
The  presence  of  organic  nitrogen  _,which  is  found 
in  the  soil  has  been  formed  by  the  decay  of  vege- 
table aud  animal  matter.  It  is  also  brought  dow'* 
in  rain  as  organic  nitrogen,  ammonia  nitrates,  and 
nitrites.  The  amount  obtained  in  this  way  was 
determined  at  Rothanisted  to  be  -I-i  lb.  per  acre  per 
annum.  But  this  varies  in  different  parts  of  the 
country.  It  is  estimated  that  an  acre  of  fertile 
soil  contains  from  6.000  to  30,000  lb.  of  nitrogen  in 
(he  first  18  inches,  but  the  larger  half  is  in  the 
AUG.  1ST,  1895.  [No.  2. 
first  9 inches,  aud  the  quantity  decreases  the  deeper 
wo  go,  96  per  cent,  of  it  being  present  as  organic 
matter. 
From  the  above  it  seems  that  we  have  an  inex« 
haust'ble  supply  of  nitrogen  in  the  soil,  when  our 
most  exhaustible  crops  (Turnips)  only  remove  about 
150  lb.  per  acre.  But  probably  not  more  than  5 per 
cent,  of  the  nitrogen  in  the  soil  is  in  the  form  of 
nitrates,  and  thus  available  as  plant  food.  Fallow 
land  always  contains  a much  higher  percentage  of 
nitrates  than  land  under  crop  ; for  instance,  the 
first  27  inches  of  soil  over  an  area  of  one  acre  of 
fallow  contains  from  33  to  60  lb.  of  nitrates;  land 
under  crop  only  contains  from  5 to  14  lb,  in  the 
same  bulk  of  roil.  This  shows  how  quickly  the 
nitrates  arc  taken  up  by  a growing  crop. 
Those  nitrates  are  most  abundantly  formed  during 
tlio  late  summer  and  early  autumn  months,  when 
the  soil  is  warm,  especially  after  cereal  and  other 
summer  crops  aro  removed.  Nitrates,  it  should  be 
remembered,  are  very  soluble  in  water,  aud  if  light 
sandy  soils  aro  allowed  to  remain  bare  during  the 
winter  a very  largo  proportion  of  this  A'aluable 
manure  will  be  washed  out  by  the  heavy  rains.  To 
prevent  this  loss  sonis  kind  of  winter  crops  should 
bo  grown,  as  these  take  up  the  nitrates.  If  the 
crops  arc  of  no  other  uso  they  can  be  dug  in 
daring  the  early  spring,  and  will  then  form  a good 
organic  manure  which  is  beneficial  to  light  sandy 
soils,  as  it  helps  to  make  them  more  retentive. 
I have  stated  that  our  most  exhaustive  crops 
remove  about  150  lb.  of  nitrogen  per  acre,  ar.d  from 
experiments  at  llothamstead  it  was  found  that  from 
35  to  15  lb.  of  nitrates  per  acre  were  washed  out 
of  the  soil  into  the  drains  per  annum,  making  the 
total  loss  of  nitrogen  about  157  lb.  per  acre  in  one 
year.  Gardeners  must  bear  in  mind  that  this  loss 
goes  on  the  same  in  garden  soils,  and  therefore  to 
keep  it  in  a fertile  coudition  we  must  replace  this 
loss  by  the  application  of  some  nitrogenous  manure, 
such  as  the  following. 
Amiaonium  Sulijitaft;. — This  is  a compound  of  ammo 
nium  and  sulphuric  acid.  It  contains  20  per  cent, 
