Dec.  r,  1892.] 
THE  TROPICAL  AGRICULTURIST, 
395 
COMPARATIVE  VALUE  OF  ANIMAL 
MANURES. 
The  application  to  the  land  of  animal  manure, 
either  alone  or  mixed  with  vegetable  substances,  has 
from  the  earliest  times  been  considered  as  the  best 
means  of  producing  fertility  in  the  soil,  or  of  restor- 
ing its  productive  powers  when  exhausted. 
Of  all  what  may  be  termed  auxiliary  manures  at 
the  command  of  the  gardener,  probably  guano  occu- 
pies the  first  and  most  important  position.  And 
although  guano  of  the  strength  in  nitrogen  formerly 
obtained  can  scarcely  be  bought  at  the  present  time, 
yet  the  unshaken  belief  in  this  manurial  agent  enter- 
tained by  many  market  gardeners  may  be  explained 
by  the  fact  that  in  certain  cases  they  get  as  good  a 
crop  from  it  now  as  they  did  previously.  The  fact 
being,  that  in  the  majority  of  cases  8 to  10  per  cent, 
of  nitrogen  is  quite  sufficient  to  apply  in  any  manui'e 
at  the  ordinary  rate,  and  the  larger  quantity  formerly 
used  was,  in  too  many  instances,  wasted. 
Guano,  as  is  probably  known,  is  composed  of  the 
excrements  of  sea-birds,  which  have  accumulated  in 
the  course  of  time,  in  layers  of  greater  or  less  depth, 
upon  uninhabited  islands  and  rocks.  Good  guano 
comes  to  us  from  those  zones  of  the  earth  in  which 
it  never,  or  at  least  extremely  seldom,  rains,  and 
from  such  islands  as  are  sufficiently  elevated  to  pre- 
vent the  overflowing  of  sea-water ; for  if  either  hap- 
pened, the  best  and  most  efficacious  portions  of  the 
guano  would  be  dissolved  and  washed  away.  If  a 
dung-heap  is  suffered  to  lie  without  attention  for 
only  a few  years  with  the  sun  shining  upon  it,  the 
air  driving  through  it,  and  the  rain  washing  its  good- 
ness away,  what  will  at  last  be  left?  Not  much, 
beyond  the  carbonaceous  and  mineral  substances 
which  could  net  be  dissolved  or  volatilised. 
Such  is  the  case  with  washed-out  and  bad  guano, 
and  this  inferior  article  is  now  very  frequently  to  be 
found  iu  commerce,  in  the  place  of  the  rich  guanos 
formerly  to  be  purchased ; therefore,  gardeners  should 
be  on  their  guard  when  buying  this  fertiliser. 
Enquiries  are  often  made  as  to  the  value  of  poultry 
manure,  and  its  comparison  with  other  animal  ex- 
crements. We  have  therefore  given  in  the  table 
below  the  quantities  of  four  of  the  principal  manurial 
constituents  contained  in  cow-manure,  pig-manure, 
and  fowl-manure ; each  in  its  natural  state  and  free 
from  litter.  The  quantities  are  shown  in  pounds  per 
ton  of  manure. 
Selected  Constituents  in  Three  Animal  Manures, 
in  lbs.  per  Ton. 
Constituents. 
Cow 
Manure. 
Manure. 
Fowl 
Manure. 
Lb. 
Lb. 
Lb, 
Potash 
7 
2 
24 
Phosphoric  acid  .... 
5 
18 
41 
Lime 
6 
33 
47 
Nitrogen 
9 
13 
87 
The  data  thtis  given  shows  that  of  the  three 
manures  quoted,  that  produced  by  cows  is  by  far  the 
least  valuable,  exoept  in  the  matter  of  potash  ; and 
it  is  generally  so  regarded.  This  may  be  explained 
by  the  large  quantity  of  fertilising  constituents  with- 
drawn from  the  food  by  the  milk  yielded.  It  has 
been  estimated  that  a milch  cow  will  carry  off  from 
a meadow  in  the  course  of  a year  by  the  milk  which  she 
yields  as  much  plant-food  as  is  contained  in  1J  ton 
of  farm-yard  manure. 
The  excrements  of  cows  contain  the  smallest 
quantity  of  nitrogen,  and  the  largest  quantity  of 
water,  amongst  the  manures  of  which  we  have  spoken. 
On  this  account  they  pass  but  slowly  into  putrefaction, 
and  become  less  heated  when  lying  in  heaps ; for 
heating  is  exclusively  a result  of  the  putrefactive 
fermentation,  aud  keeps  pace  with  this  process.  In 
addition  to  this,  the  substance  of  these  excrements 
does  not  acquire  a crumbling  texture  by  lying  or 
desiccation,  but  becomes  saponaceous  and  compact ; 
by  which  its  distribution  in  the  soil,  as  well  as  its 
decomposition  and  liquefaction  are  rendered  more 
difficult.  The  slow  but  persistent  action  of  this  manure 
is  thus  explained  at  once. 
Pig-manure  varies  in  character  probably  more  than 
that  of  any  of  our  domestic  animals,  for  pigs  are  of 
all  creatures  the  most  indiscriminate  in  their  diet, 
and  their  excrements  must,  on  that  account,  vary 
much,  according  to  the  kind  of  food  they  may  happen 
in  any  particular  case  to  obtain.  Containing  so  much 
water  and  so  little  nitrogen,  dung,  like  that  from 
cows,  but  slowly  undergoes  decomposition  in  the 
soil,  and  is,  therefore,  regarded  as  one  of  the  “cold 
manures.” 
Fowl-manure,  like  that  of  guano  from  sea-birds, 
is  a powerful  fertilising  agent ; it  contains  as  much 
or  more  nitrogen  than  many  of  the  commercial 
manures  in  the  market,  besides  1 per  cent  of  potash, 
and  1'83  per  cent,  of  phosphoric  acid.  The  dung  of 
fowls  contains  not  only  the  undigested  food,  but  also 
in  solid  form  the  excretions  of  the  kidneys,  which  in 
cattle  are  voided  as  urine,  and  are  apt  to  be  lost 
both  by  drainage  and  by  rapid  fermentation.  Thus 
the  richer  food,  and  the  fact  that  the  dung  of  fowls 
is  comparatively  dry,  explains  the  higher  percentage 
of  nitrogen,  phosphoric  acid,  and  potash  in  it.  Care 
in  its  use  is  necessary,  as  also  with  guano  and  other 
of  the  strong  manurial  agents,  or  mischief  may  be 
done  to  the  plants  for  which  it  is  employed.  If  dis 
solved  in  water,  it  may  advantageously  be  applied 
to  all  fruits  trees,  especially  during  the  period  of 
fruiting  ; also  for  Tomatos,  Onions,  Chrysanthemums, 
Fuchsias,  Geraniums,  &c.  If  fowl-manure  is  used 
for  Vine  borders,  for  which  purpose  it  is  admirably 
adapted,  it  should  be  mixed  with  equal  quantities  of 
charcoal-dust  or  cinder  siftings. 
Farmyard  manure  is  particularly  liable  to  fluctua- 
tions in  its  chemical  composition,  according  to  its 
preparation,  and  the  amount  of  food  and  litter 
pupplied  to  the  animals.  The  following  may,  how- 
over,  be  taken  as  about  the  average  composition 
per  ton : — 
Selected  Constituents  in  1 ton  of  Farmyard  Manure . 
Lb. 
Potash  , . 11 
Phosphoric  acid . . 8 
Lime  . . . , . . . , . . . , 18 
Nitrogen . , . . 12 
It  has  been  found  that  by  far  the  larger  part  of 
these  ingredients  in  farmyard  manure  are  in  an  in- 
soluble connection — that  is  to  say,  in  a state  in  which 
plants  cannot  feed  upon  them  until  they  have  under- 
gone further  change. 
For  exampfe,  a portion  of  the  nitrogen  in  farmyard 
manure  exists  as  ready-formed  ammonia — our  sens 
of  smell  readily  detects  this  fact — but  a large  proportion 
becomes  only  very  gradually  converted  into  ammonia, 
as  the  nitrogenous  organic  matter  decomposes  in 
the  soil. 
Thus,  owing  to  the  slow  decomposition  of  farm- 
yard or  stable-manure,  and  the  tardiness  with  which 
a large  proportion  of  its  nitrogen  becomes  available 
for  the  use  of  the  growing  crop,  three  or  four  times, 
or  even  more  nitrogen,  than  in  activi  artificial 
manures  or  fowl-dung,  must  be  applied  to  produce 
the  same  effect  upon  the  immediately  succeeding  crop. 
Stable-dung,  however,  possesses  two  very  important 
properties — one  mechanical  and  the  other  chemical. 
By  reason  of  its  bulk  and  the  quantityof  organic 
matter  it  contains,  it  serves  to  render  the  soil  more 
open  and  porous,  and  so  to  enable  it  not  only  to 
retain  more  water  in  a favourable  condition,  but 
also  to  absorb  and  retain  more  of  the  valuable 
constituents  of  the  manure,  and  thus  to  arrest  the 
passage  of  them  in  solution  below  the  root-range  of 
the  plants.  Further,  by  the  gradual  decomposition 
of  the  organic  matter  of  the  dung  the  pores  of  the 
soil  become  filled  with  carbonic  acid,  whioh  prob- 
ably serves  to  retard  the  oxidation  of  the  ammo- 
nia into  the  more  soluble  form  of  nitric  acid,  in 
which  it  would  be  more  liable  to  be  washed  out  of 
the  soil,  and  lost  by  damage,  At  the  same  time, 
the  carbonic  acid  evolved  in  the  decomposition  of 
the  stable-dung  will,  with  the  aid  of  moisture, 
serve  to  render  the  mineral  resources  of  the  soil 
more  soluble.— J.  J,  Win, is,  Harpendem—  GardcncrC 
Chronicle, 
