6 
THE  TROPICAL  AGRICULTURIST. 
[July  i,  1895. 
Oq  ploughing  a pea  crop  into  the  soil  on 
which  it  grew  most  substantial  gain  accrues,  for 
not  only  is  the  mineral  matter  of  the  crop  returned 
in  a form  readily  assimilable  by  subsequent  crops, 
and  lar:e  stores  of  vegetable  matter  which  have 
their  origin  in  the  atmosphere  a id  on  decaying  form 
valuable  humus  are  added  to  the  soil,  but  in  addition, 
considerable  quantities  of  nitrogen  (a  costly  con- 
stituent of  manures ) are  brought  into  the  soil,  this 
nitrogen  having  been  derived  frnn  the  atmosphere 
whence  other  crops  are  unable  to  extract  it.  A 
soil  thus  treat  d is  considerably  enrich  d while  its 
mechanical  condition  or  heart  is  imuroved. 
The  mechanical  action  of  the  roots  of  intermediate 
crops,  legumiirous  and  others,  must  be  of  considerable 
service  in  improving  stiff  soils;  for  when  tbe  growing 
c op  dies,  or  is  reaped,  the  roots  which  have  pene- 
trated to  various  depths  decay,  anl  leaving  channels 
in  the  stiff  subsoil,  admit  air,  and  encourage  the 
downward  tendency  of  the  roots  of  the  Lime  trees. 
1 cannot  lay  too  great  stress  on  the  importance  of 
tnaintaining  the  soil  in  good  condition,  for  I have 
seen  orchards  where  the  trees  have  been  in  a dyin? 
condition  from  starvation,  while  the  soil  itself 
containel  a superabundance  of  plant  food,  but  in 
an  unavailable  state.  In  such  a case  a thorough 
till  ng  followed  by  a green  dressing,  would  have  been 
attended  with  excellent  results  while  the  application 
of  manures  would  have  proved  useless. 
Hiving  secured  good  tilth  with  a soil  in  "good 
heart  ’ a condition  which  involves  the  presence  of 
a fair  supply  of  humus,  it  becomes  necessary  to 
inquire  what  items  of  plant  food  a Lime  crop  will 
remove  from  the  soil  and  whether  it  will  be  necessary 
to  provide  for  the  restoration  of  any  constituent 
lik  ly  to  prove  deficient. 
From  analyses  which  1 made  some  time  ago,  I 
obtained  the  following  information  bearing  directly 
on  this  side  of  the  question. 
Ripe  Limes  contain  about  "1)5  to  '40  per  cent  of 
mineral  constituents  having  the  following  com- 
position. 
COMl’OSitlON  OF  Asil 
Pounds  of  E.vch 
PER  Cent. 
CONSTITUF.N-r  IN 
1000  lb.  OF  Fruit 
Potash 
47-21 
1-888 
Soda 
1 88 
•067 
Lime  - * 
29-17 
1-167 
Magnesia 
•270 
Oxide  of  Iron  . , 
1-02 
•oil 
Phosphoric  Acid 
1T40 
•458 
Sulphuric  Acid 
•2(i 
•on 
Chlorine 
1-.S1 
•07;? 
Bilica 
•oil 
100  40 
neduct  0 II  Cl. 
•1 1 
99-99 
Now  the  yield  of  fruit  from  an  acre  of  Lime 
orchard  varies  very  much,  but  for  purposes  of 
calculation  we  may  take  the  quantity  at  from  50  to 
K«)  barrels  of  fruit  per  acre,  per  annum,  when  in 
full  bearing,  or  about  from  10,000  to  20,000  lb. 
V glance  wi'l  show  that  so  far  as  the  mineral 
matter  is  concerned  the  heaviest  demands  will  fall 
on  the  potash,  the  lime  and  the  phosphoric  acid,  and 
that  the  amouuts  removed  by  a crop  of  lime  annually 
will  be  about  as  follows:— 
Potash  ... 
Thme  ...  .••  12  to  24  lb. 
Phosphoric  Acid  ...  0 to  18  lb. 
These  will  be  the  amounts  per  acre  abstracted 
from  the  soil  when  the  fruit  is  entirely  taken  away 
from  the  orchards;  but  in  most  cases  the  skins  and 
pulp  of  the  fruit,  after  the  juice  has  been  expressed, 
are  returned  to  the  soil,  and  thus,  will  reduce  the 
demands  on  the  plant  food  of  the  soil  to  about  one 
^'*'^l'lcaring  these  facts  in  mind,  it  becomes  com- 
naratively  easy  to  calculate  what  amount  of  various 
manurial  constituents  should  be  applied  iu  order  to 
maintaiu  unimpaired  the  fertility  of  the  soil. 
So  far  as  I am  aware  the  volcanic  .soils  of  the 
West  Indies  on  which  the  Lime  orchards  are  situated 
are  for  the  most  part  very  deficient  in  lime  and  in 
phosp’ioric  acid.  Of  the  lime  which  is  present,  a 
very  large  proportion  is  present  in  a form  which 
is  of  very  little  immediate  value,  being  chiefly 
silicate,  while  the  available  rarhonate  of  lime  is 
usually  present  in  very  small  quantities  ; and  as 
this  plays  a very  important  part  in  the  chemistry 
of  the  soil,  in  aiding  the  transformation  of  nitro- 
genous substances  into  nitrates,  in  which  form 
Plants  assimulate  their  nitrogen,  it  is  desirable  to 
add  lime  to  the-e  soils,  if  possible  to  do  so  at  a 
reasonable  cost.  The  deficiency  of  phosphoric  acid 
is  readily  made  up  by  the  application  of  various 
phosphatic  ma'  ures.  As  many  soils  are  so  deficient 
in  free  lime  it  would  seem  desirable  to  avoid  the 
use  of  acid  preparations  of  phosphoric  acid  such  as 
superphosphate  and  to  employ  instead  such  substances 
as  bone  dust,  precipitated  phosphate,  or  basic 
phosphate  otherwise  known  as  Thomas  phosphate. 
The  e are  slow  noting  manures  who?e  effect  should 
be  apparent  over  a considerable  period,  a point  of 
some  value  in  manuring  fruit  trees. 
These  volca’dc  soils,  although  containing  moderate 
amounts  of  potash,  are  not  over  stocked  with  that 
constituent  in  an  easily  assimilable  form,  hence  it 
is  desirable  to  add  small  quantities  of  potash  when 
app'ying  phosphatic  and  other  manures.  If  an 
intermediate  crop  is  grown  and  removed  as  has  been 
suggested  above,  then  the  application  of  potash 
becomes  of  paramount  importance,  such  crops  as 
potatoes  or  arrowroot  take  large  amounts  of  potash 
from  the  soil  and  their  exhausting  effects  would 
soon  be  felt  nnless  this  contituent  was  replaced  by 
artificial  manuring. 
As  to  the  nitrogenous  manuring  of  lime  trees  we 
have  little  to  guide  us  in  the  way  of  chmical  literature 
on  the  subject.  Experiments  show  that  the  appear- 
ance of  the  trees  is  greatly  improved  by  the  appli- 
cation of  nitrogenous  manures,  and  it  would  seem 
that  general  health  and  fertility  should  be  increased 
in  like  manner.  The  growth  of  green  dressings  of 
pigeon  peas  as  described  above,  coupled  with  the 
application  of  the  pen  manure  from  the  animals 
employed  in  working  a Lime  estate,  will  probably 
constitute  the  chief  sources  of  nitrogenous  food 
supp'y.  Should  artificial  manures  be  purchased,  such 
substances  as  dried  b ood  or  cotton  seed  cake  or 
other  seed  cakes,  being  sointwhat  slow  in  their 
action  and  lasting  iu  their  effect,  are  preferable  for 
the  purposes  of  fruit  farming  to  such  soluble  forms 
of  nitrogenous  manure  as  Sulphate  of  Ammonia 
or  Nitrate  of  Soda 
The  other  constituents  of  the  soil  arc  present  i.i 
sufficient  quantities  in  those  orchards  which  I have 
bad  an  opportunity  of  examining,  audit  would  seem 
therefore  that,  having  got  the  soils  of  a Lime  orchard 
into  good  mechanical  condition.  Nitrogen,  Fhos- 
phoicB  acid.  Lime  and  potash  are  the  only  inaiiunal 
const  uents  requiring  much  thought. 
THE  MANGROVE  CONCESSION. 
In  our  last  number  w'e  informed  our  readers  that 
a concession  had  been  granted  for  the  purpose  of 
extracting  tannic  acid  from  the  baik  of  the  Mangrove, 
of  which  there  are  six  species  found  in  Ceylon, 
namely:  — 
Rhizophero  mucronata,  S.,  Ivadol ; T.,  Kandal. 
oandolarie,  S.,  Kadol ; T.,  Kandal.* 
Qfiops  candolleana  — T.,  Chirukandal. 
- ,,  Roxburghiana  — — 
Bruguiera  gymnorhiza  — T.,  Kandal. 
,,  caryopbylloides  — — 
To  obtain  the  bark  two  systems  are  in  vogue.  In 
Borneo  the  trees  themselves  are  felled,  and  then 
the  bark  is  stripped,  while  in  Ceylon  the  hark  is,  as 
a rule,  roughly  stripped  oti  and  the  tree  is  left  stand- 
ing, but  it  is  often  so  damaged  that  it  eventually 
dies.  It  has  been  pointed  out  to  us  that  there  might 
be  a better  way  than  either  of  those  two  methods, 
and  this  would  bo  to  spokeshave  the  trees  as  was 
doao  with  Cinohoua.  Cau  any  of  our  readora  inform 
