540 
Fourth  Report  on  the  Analysis 
of  ash,  or  34S£  lbs.  on  the  acre.  The  second  gave  2*24  per 
cent,  of  ash,  or  44/  lbs.  to  the  acre. 
The  composition  of  these  mineral  matters  would  be  as  under 
— in  lbs.  and  tenths  : — 
In  the  1st  Crop. 
In  the  2nd  Crop. 
In  both. 
lbs. 
lbs. 
lbs. 
Silica 
32-2 
152-5 
184-7 
Phosphoric  Acid  . 
32-4 
21-9 
57-3 
Sulphuric  Acid  . 
12-4 
18-9 
31-3 
Carbonic  Acid 
40-5 
5-1 
45-6 
Lime 
33-2 
40-8 
74-0 
Magnesia  .... 
8-6 
11-1 
19-7 
Peroxide  of  Iron  . 
4-6 
2-8 
7-4 
Potash  .... 
174-2 
99-1 
273-3 
Soda 
•3 
— 
•3 
Chloride  of  Potassium 
— 
77-8 
77-8 
Chloride  of  Sodium  . 
10-1 
14-0 
24-1 
- 
348-3 
447-0 
795-5 
If  the  data  upon  which  the  preceding  numbers  depend  are  at 
all  near  the  truth,  the  quantity  of  mineral  matter  removed  by  the 
two  crops  of  meadow  grass  far  exceeds  anything  that  lias  come 
before  us  in  the  examination  of  other  kinds  of  produce.  The 
first  crop  is  calculated  to  weigh  when  cut  12  tons  3 cwt.  per 
acre — if  made  into  hay,  its  weight  would  of  course  be  greatly  di- 
minished. The  quantity  of  water  in  well-made  hay  may  be 
taken,  for  the  sake  of  argument,  at  from  15  to  20  per  cent.  The 
12  tons  3 cwt.  of  grass  would,  when  absolutely  dry,  weigh 
3375  lbs.,  or  in  the  state  of  ordinary  hay  3970  lbs.,  which  is  about 
1 ton  15i  cwt. 
The  second  crop  in  the  same  way  would,  by  drying,  from 
S tons  J8i  cwt.  be  reduced  to  about  2 tons  124  cwt.  (more  cor- 
rectly 5878  lbs.)  of  hay. 
The  whole  produce  of  these  two  crops  would  therefore  be,  in 
the  state  of  hay,  4 tons  8 cwt.  of  hay,  a quantity  which  seems 
large,  but  is  not  impossible  considering  the  extraordinary  fertility 
produced  by  irrigation.  It  is  worthy  of  remark  in  this  place 
that  the  enormous  quantity  of  mineral  matter  periodically  re- 
moved from  the  soil,  and  amounting  to  more  than  7 cwt.,  must 
in  great  part  be  furnished  by  the  water,  since  the  meadows  in 
question  are  not  otherwise  manured. 
In  calculating  the  mineral  composition  of  ordinary  meadow- 
grass  (not  irrigated),  we  may  with  tolerable  safety  make  use  of  the 
foregoing  data,  with  the  requisite  reduction  for  the  weight  of  the 
crop.  Irrigation,  whilst  affecting  the  quantity  of  the  grass,  pro 
bably  leaves  its  mineral  composition  relatively  unaltered. 
