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46 BULLETIN OF THE BUSSEY INSTITUTION. 
clusion can be strengthened still further, as regards the leached woods, 
by considering how small a proportion of fertilizing ingredients are 
contained in wood in its natural condition. Fresh sawdust, for exam- 
ple, even that from ey woods, can rarely, if ever, be considered an 
economical manure; since the proportions of all the fertilizing sub- 
stances, excepting nitrogen, that are contained in it, are so small that 
they may be regarded as lost in the mass of useless ligneous matter. 
The proportion of nitrogen, moreover, that is contained in wood is 
less than that in turf and in most peats and many pond-muds and 
Joams ; so that even in this respect, sawdust is inferior for compost to 
these materials, which are almost always readily accessible, and to be 
had as cheaply. From the table on pages 207-245, Vol. I., of this 
Bulletin, it appears that 100 Ibs. of beech-wood, for example, contain 
only about one-tenth of a pound of real potash, no more than five 
hundredths of a pound of phosphorié acid, and at the utmost (page 32) 
no more than a pound of nitrogen, even in wood that has been artifi- 
cially dried. But as has been shown on page 267, Vol. I., of this 
Bulletin, peats often contain more than 2o% of that element. Of 33 
New England peats examined by Professor Johnson, barely one-third 
of the samples contained less than 1}% of nitrogen, and only four of 
the samples contained less of that element than the poorest of Chevan- 
dier’s woods (0.81%). 
In respect to nitrogen, sawdust is doubtless as good or better than 
straw, which usually contains no more than one-third of one per cent 
of nitrogen, but since straw * contains a much larger proportion of 
potash (0.5 to 1.0%) than wood, and is decidedly richer in phosphoric 
acid (0.2 to 0.3%) also, and the other essential ash ingredients of 
plants, it has always been rightly esteemed a much better manure than 
sawdust. A comparison, such as this, of the constituents of straw with 
those of sawdust, explains at once why it is that in respect to the quality 
of the manure obtained, sawdust has been found in practice to be but 
a poor substitute for straw for bedding animals. It is true that the 
different absorptive powers of the two materials for the liquid parts of 
the manure may also have a certain influence on the quality of the 
final mixture; but it is plain, on the face of the matter, that manure 
from well-kept stables where sawdust is used for bedding, must neces- 
sarily be poorer in inorganic materials than that from similar stables 
where the manure is mixed with straw. 
* See table in Johnson’s ‘‘ How Crops Grow,” p. 382. 
