FERTILIZING SUBSTANCES. 147 
miss it. Four-fiths at least of what the eminent 
agricultural chemist considers the most efficacious 
manure for coffee must consist of potash, bone-dust, 
and bones in the shape of superphosphate; while the 
sulphate of ammonia added should never exceed one- 
fifth. In four out of six recipes indeed given by Dr. 
Voelcker, the proportion. is only 15 per cent, The 
proportions applied as Dr. Voelcker states of the f:r- 
tilizing salts he recommends must depend on the 
condition of the soil as revealed by analysis; but 
even where analysis cannot be obtained, any planter 
would be safe in applying a small dressing of the 
substances named to good soil (say 3 cwt. per acre) 
so as to keep it good; and a larger dressing (say 5 
ewt. per acre) with about an equal quantity of poonac 
to fertilize poor or restore exhausted soil. The appli- 
cation, to secure the fullest results, ought, we learn 
from a planter of experience, to be made annually , 
but once in two years would keep coffee fairly in 
heart. A most important point to be remembered is 
that every cwt. added to the normal produce of an 
estate is almost clear profit. It follows that, if by 
adding 3 cwt. per acre annually of manure the yield 
is raised from 5 ewt. to 7, 8, 9, or 10 cwt., the 
immediate profit will be large, while the land will 
be kept permanently in good condition. The cost of 
3 ewt. of Dr. Voelcker’s mixture ought not when 
apphed to reach £3, while 2 cwt. additional of coffee 
ought to realize £6 to £7 gross, of which, according 
to our authority, a very large proportion would be 
profit. Can any of our readers favour us with an 
analysis of castor-oil cake, so that we may be able 
to see why it is so nuch better than coconut poonac 
which we know yields to analysis the elements of 
coffee? Dr. Voelcker, the man of science, attaches 
far less importance to organic matter than does the 
merely practical planter Mr. Taylor. Organic matter 
is of great importance, nevertheless; but as fallen 
leaves, though they contain the minimum of fertiliz- 
ing salts, are yet most eflicacious in securing the 
action on soil which results from warmth and moist- 
ure. In the soils examined by Dr. Voelcker, the 
proportion of organic matter varied from a minimum 
of 5:07 to a maximum of 13:13; oxides of iron from 
2°64 to 12°84; alumina from 6°01 to 16°47; while 
insoluble silicious matter proved to be never below 
59°57 (alumina being in this case high in proportion), 
rising to 82°23. Our soil consists of about 98 per cent 
of the organic and mineral substances named, with 
not much more than traces in each case of such salts 
as sulphate and carbonate of lime, magnesia, phcs-l 
phoric acid, potash, and soda. In the very best svil 
