AS A MANURE FOR POTATOES. 365 
are thus introduced into the fields when the manure 
is scattered over them.” 
“ By the use of night-soil we avoid this incon- 
venience, and hence it is, that in China, where 
it is exclusively employed, the corn-fields are 
remarkably exempt from weeds.” 
In order to obtain uniform success by the use 
of Guano, or of other manures, a knowledge of 
the constituent principles of a soil is requisite, 
and this can only be done when the farmer can 
obtain an analysis of it by a competent chemist. 
Guano, however, even when genuine, sometimes 
fails, is not always equally productive, yet, in 
some soils and localities, it is superior to most of 
the substances hitherto employed. 
A neglect in using the following precaution, is 
a frequent cause of failure. It should be well 
mixed with the soil, either alone, or combined 
with ashes, charcoal, sand, or any other sub- 
stance which can be easily procured, so that it 
does not come into actual contact with the article 
sown or planted. Its properties are soon deve- 
loped; but if it be placed in the ground in dry 
weather, or if it be not watered, it will fail. It 
3c 
