614 
JOtlRKAL  OF  nOUfiGULTDRE  AFtl)  COTTAGE  G A  HEFNER, 
Decfmber  ?4  1898. 
for  there  is  still  some  heat  left  from  the  oxidation  of  the  humas  to  aid  in 
warming  the  soil. 
It  should  be  observed  also  that  humus,  as  a  rule,  imparts  a  darker 
colour  to  the  soil,  and  thus  causes  it  to  absorb  more  of  the  heat  of  the 
san,  lu  autumn  humms  soils  are  not  affected  by  sudden  changes  of 
temperature  to  the  same  extent  as  soils  poor  in  humas,  the  difference 
freqnently  being  sufficient  to  ward  off  an  early  frost  and  to  enable 
corn  in  the  Northern  States  to  reach  its  full  maturity. 
Applications  of  humus-forming  materials,  such  as  manure,  have 
frequently  been  observed  to  raise  the  temperature  nearly  a  degree,  and 
this  in  colder  climates  is  often  sufficient  to  prevent  the  growth  of  a  crop 
from  being  checked.  In  the  colder  regions  soils  which  are  poor  in 
humus  freeze  much  deeper  than  soils  which  are  richer  in  humus. 
In  the  preceding  notes  the  attempt  has  been  made  (o  demonstrate 
that  the  chemical  action  of  humus  in  providing  available  plant  food  in 
the  soil  makes  it  of  the  greatest  value  as  a  fertiliser ;  that  it  assists 
materially  in  bringing  about  the  physical  conditions  in  the  soil  best 
suited  to  the  growth  of  plants ;  that  it  furnishes  a  medium  peculiarly 
suited  to  the  activities  of  such  organisms  as  those  of  nitrification,  which 
are  useful  in  plant  growth  ;  and  that  loss  of  humus  from  the  soil  is 
always  attended  by  a  marked  decline  in  its  productiveness.  It  is  now 
important  to  discuss  the  means  "by  which  this  valuable  constituent  of 
soils  may  be  conserved  and  increated. 
Means  op  Maintaining  the  Humus  op  the  Soil. 
On  account  of  the  variable  composition  of  humus  it  is  difficult  to 
state  the  definite  amount  which  should  be  present  in  all  soils.  A  large 
amount  of  humus,  containing  a  very  high  per  cent,  of  carbon,  approach¬ 
ing  in  many  cases  the  composition  of  charcoal,  is  not  as  valuable  as  a 
smaller  amount  of  humus  which  is  capable  of  readily  undergoing  decom¬ 
position. 
With  an  excessive  amount  of  water,  and  in  the  absence  or  scarcity  of 
the  proper  soil  elements,  like  lime,  potash,  and  humus-forming  materials 
may  produce  sour  soils,  but  in  good  soils  well  stocked  with  lime  there  is 
but  little  danger  of  this  result.  It  is  safe  to  conclude,  therefore,  that 
soils  as  a  rule  will  be  benefited  by  those  systems  of  culture  which  con¬ 
serve  or  increase  the  humus  content. 
The  liberal  use  of  well-prepared  farm  manures,  green  manuring,  and 
a  judicious  rotation  of  crops  are  the  three  most  important  means  of  main¬ 
taining  the  humus  of  the  soil.  The  preparation"  and  use  of  farm  manures 
and  green  manuring  have  already  been  discussed  in  some  detail  in 
balletins  from  the  U.S.  Department  of  Agriculture,*  and  it  is  only 
necessary  to  briefly  refer  to  these  subjects  here. 
In  the  arid  regions,  and  in  many  of  the  prairie  sections,  the  proper 
preparation  of matmres  is  a  problem  which  has  not  as  yet  been 
satisfactorily  solved.  On  account  of  the  slowness  of  decomposition  of  the 
straw  in  the  manure,  many  farmers  in  the  regions  named  have  begun  to 
look  upon  manure  as  a  detriment  rather  than  a  benefit  to  the  land.  In 
these  regions,  however,  the  soil  is  in  greater  need  of  humus  than  in  the 
regions  of  uniform  summer  rains,  and  it  is  of  the  highest  importance  to 
devise  some  system  of  preparing  the  manure  produced  on  the  farm  so 
that  it  may  be  utilised  to  the  fullest  extent. 
The  humus  materials  of  the  soil  may  be  increased  by  the  use  of  well 
prepared  muck.  It  is  best  to  draw  the  muck  during  the  summer.  After 
drying  it  can  be  used  as  an  absorbent  in  stables,  for  which  purpose  it  is 
very  valuable,  many  mucks  having  the  power  of  absorbing  more  than 
their  own  weight  of  liquid.  When  muck  is  mixed  with  urine,  it  readily 
undergoes  fermentation,  which  increases  its  fertilising  value.  The 
brown  mucks  are  much  quicker  in  their  action  than  the  black.  A  little 
marl  or  laud  plaster  mixed  with  the  muck  keeps  it  from  forming  sour 
mould. 
Clover  and  plants  of  the  leguminous  family  are  more  suitable  for 
green  mamiring  purposes  than  any  other  class  of  farm  crops,  because,  in 
addition  to  supplying  an  abundance  of  humus-forming  materials,  they 
add  to  the  soil  large  amounts  of  nitrogen  drawn  principally  from  the 
air.  In  the  South  the  Cowpea  is  extensively  used  for  this  purpose  with 
good  results,  and  crimson  Clover  has  proved  valuable  on  the  sandy  cosst 
soils  of  the  Eastern  States.  Where  land  is  cheap  and  fertilisers  and 
labour  are  expensive,  green  manuring  will  doubtless  prove  to  be  the 
most  economical  way  of  maintaining  fertility.  W’’here  land  has  a  high 
value  and  labour  is  cheap,  better  returns  will  be  obtained  from  feeding 
the  crop  to  stock  and  using  the  manure  rather  than  resorting  to  green 
manuring. 
notation  of  Crops  —  Another  means  of  maintaining  the  humus  of  the 
soil  is  the  practice  of  proper  systems  of  rotation  of  crops.  The  general 
laws  which  apply  to  the  rotation  of  crops  are  in  perfect  accord  with  the 
conservation  of  the  soil  hnmus,  but  definite  rules  cannot  be  given  on 
account  of  the  variations  in  soil  and  climate  of  different  parts  of  the 
country. 
The  methods  of  farming  which  are  the  most  destructive  of  the  soil 
humas  are  continuous  grain  cropping  without  manures  and  the  con¬ 
tinuous  cultivation  of  Cotton,  corn,  and  Potatoes,  while  the  methods 
which  increase  the  soil  humus  are  the  growing  of  grass  crops  and  dairy 
and  stock  farming,  which  result  in  the  production  of  large  quantities  of 
manure.  These  statements  are  by  no  means  intended  to  discourage 
grain.  Potato,  or  Cotton  growing,  but  they  are  intended  to  encourage  a 
definite  course  of  rotation  in  the  culture  of  these  crops,  and  the  use  of 
more  well-prepared  farm  manures,  so  as  to  keep  up  the  humus  of  the 
soil. 
*  Palmers  Bullelia,  Nos.  16  and  21. 
Summary. 
1,  The  decline  in  the  crop-producing  power  of  many  soils  is  due  to  a 
loss  of  the  partially  decomposed  animal  and  vegetable  matters  known  as 
humus. 
2,  The  humus  of  the  soil  is  decreased  by  the  continuous  cultivation 
of  grain,  Cotton,  Potatoes,  or  any  crop  with  which  the  land  is  kept 
constantly  under  the  plough  without  the  addition  of  any  humus-forming 
materials. 
3,  The  loss  of  humus  involves  a  loss  of  the  nitrogen,  which  is  one  of 
the  elements  composing  humus.  The  loss  of  nitrogen  from  the  soil  is  not 
always  due  simply  to  the  nitrogen  removed  by  the  crop,  but  is  frequently 
caused  by  waste  of  the  humus  by  improper  methods  and  systems  of 
cultivation. 
4,  The  humus  of  the  soil  is  increased  by  the  use  of  well-prepared 
farm  manures,  green  manures,  and  by  a  sjstematic  rotation  of  crops  in 
which  grasses,  or  preferably  Clover,  form  an  important  part, 
5,  The  loss  of  humus  from  the  soil  results  in  decreasing  its  powsr  of 
storing  up  and  properly  supplying  crops  with  water.  Soils  with  a  liberal 
amount  of  humus  are  capable  of  more  effectually  withstanding  drought 
than  similar  soils  with  less  humus.  lu  arid  regions  the  loss  of  humus 
from  the  soil  is  more  serious  than  in  the  regions  of  continuous  summer 
rains, 
6,  In  sandy  soils  the  loss  of  humus  is  most  severely  felt.  In  poorly 
drained  soils,  where  there  is  a  deficiency  of  lime,  potash,  and  other 
similar  materials,  the  humus  may  form  sour  mould,  but  this  can  usually 
be  corrected  by  a  dressing  of  lime,  marl,  or  wood  ashes. 
7,  Humus-forming  materials, like  the  decaying  animal  and  vegetable 
matters  in  farm  manures,  have  the  power  of  combining  with  the  potash 
and  phosphoric  acid  of  the  soil  to  form  bumates  which  are  readily 
assimilated  by  plants  when  acted  upon  by  the  proper  soil  organism. 
These  hnmates  thus  increase  to  a  marked  extent  the  available  plant 
food  of  the  soil. 
8,  Farm  manures  and  other  humus-forming  materials  are  not  only 
valuable  for  the  elements  of  fertility  which  they  contain,  but  also  for 
the  power  of  making  the  inert  material  of  the  soil  more  available  to 
plants. 
9,  In  soils  where  there  is  a  good  stock  of  reserve  materials  it  is 
cheaper  to  cultivate  fertility  through  the  agency  of  humus  than  it  is  to 
purchase  it  in  the  form  of  commercial  fertilisers. 
HOYAL  HORTICULTURAL  SOCIETY. 
December  15th. 
Scientific  Committee.— Present :  Dr.  M.  T.  Masters  (in  the 
chair)  ;  Dr,  Bonavia,  Mr.  Michael,  Rev.  W.  Wilks,  Rev.  G.  Henslow 
(Hon.  Sec). 
Primula  sinensis  and  Uyirid. — Mr.  E.  Hyde  of  Ealing  exhibited  at 
the  meeting  held  on  November  23rd  three  fine  plants  of  an  improved 
form  of  P,  sinensis,  raised  from  an  originally  wild  plant.  They  closely 
resembled  drawings  of  this  species  when  first  introduced  about  1820,  A 
botanical  certificate  was  unanimously  awarded  to  Mr.  Hyde  for  them. 
He  also  showed  a  hybrid  raised  between  this  species  (male)  and 
P.  obconioa  (temale),  in  which  the  form  of  the  umbel,  as  well  as  that  of 
the  leaf,  more  resembled  those  of  P.  obconica.  The  segments  of  the 
petals  were  flat  and  not  reflexed,  and  but  slight’y  cusped.  These 
differences,  however,  were  not  considered  to  be  sufficiently  pronounced 
to  be  regarded  as  well  defined  intermediate  characters,  so  that  it  was 
apparently  a  case  of  prepotency  on  the  part  of  the  female  parent 
(P.  obconica).  Dr.  Masters  gave  an  interesting  account  of  the  intro¬ 
duction  of  the  wild  plant  into  England.  Dr.  Henry  first  pointed  it  out 
to  him  among  a  collection  of  dried  plants  at  Kew,  which  he  had  made 
in  the  mountains  of  Central  China.  Dr.  Masters  was  thus  enabled  to 
recognise  it  growing  in  the  gardens  of  Appley  Towers,  Isle  of  Wight,  the 
seed  having  been  sent  over  by  one  of  the  family.  Thence  it  passed  into 
the  hands  of  Messrs.  Sutton,  who  have  tried  to  cross  it,  but  hitherto  it 
has  appeared  to  resist  all  attempts.  Further  particulars  will  be  iound 
recorded  in  the  “  Gardeners’  ChroHicle,"  January  26th  and  November 
23rd,  1889,  November  loth,  1890,  and  in  Mr.  A.  W.  Sutton’s  paper  on 
Chinese  Primulas,  "  Jl,  R  H.  S,,”  1891,  vol.  xiii,,  p,  99. 
Catalpa  Mynonioides. — Dr.  Bonavia  exhibited  specimens  of  these 
curiously  winged  seeds,  but  they  did  not  appear  to  have  been  fertilised, 
as  no  embryo  could  be  detected  in  them.  The  seed  vessel,  which  is 
rarely  seen  in  this  country,  is  nearly  a  foot  in  length. 
Canker  in  Apple  Trees — Dr.  Masters  exhibited  specimens  of  this 
common  disease,  which  has  hitherto  baffled  investigations  as  to  its  source, 
but  the  examples  shown  bore  numerous  red  fructifications  of  the  fungus 
Nactrla  ditissima  bursting  through  the  bark. 
Pinut  Palfoureana  var.  aristata. — He  also  showed  specimens  of  the 
cones  of  this  Pine,  which  ia  a  native  of  the  alpine  regions  of  Colorado. 
They  were  received  from  Mr.  A.  D.  Webster,  The  shoots  bearing  the 
young  cones  bore  short  stout  leaves,  unlike  those  on  a  vegetative  shoot, 
on  which  they  were  longer  and  more  slender,  though  Dr.  Masters 
observed  that  the  anatomical  peculiarity  of  having  a  single  resin  canal  is 
the  same  in  both;  The  scales  of  the  ripe  cone  have  the  external  bracts 
terminatirg  in  an  awn-like  tip,  which  doubtless  suggeeUd  the  varietal 
name. 
Tomato  Fruits  Diseased. — He  also  brought  some  fruits  badly  diseased. 
It  appeared  to  be  an  advanced  stage  of  the  “yellow  spotted  ”  form  ;  it 
was  forwarded  to  Kew  for  investigation. 
Ilex  othera  fruit. — Dr.  Masters  also  showed  a  fruiting  branch  of 
