i6 
Garden Work 
But the washing out of soluble plant food is not the 
only loss sustained by a carelessly attended and exposed 
manure heap. There is a class of bacteria which does 
not change the manure into liquid plant food, but into 
a gas called “ammonia”. Now this, when changed into 
a nitrate, is one of the most valuable plant foods con- 
tained in farmyard manure, and its loss should be prevented 
as much as possible. This can be done by building the 
manure into a compact mass, thus preventing the multipli- 
cation and work of this class of bacteria also. For these 
reasons it is better to keep manure in one heap — that is, 
if it is obtained before being required for use — rather 
than in many small heaps on the garden. It should be 
spread on the ground only when required for digging in. 
It is, Oi course, with farmyard manures that one has 
principally to deal. It is, however, advisable to have 
some practical acquaintance with some of the chief artificial 
manures. 
When manuring with artificial manures you supply 
food for the crops alone. They have no effect on the 
soil, and, as a rule, only sufficient is supplied for the 
present need of the crops. Whereas, with farmyard 
manure we not only supply the crops with food, but 
make a change in the physical condition of the soil; that 
is, we make it denser, or able to contain more moisture, 
in the case of light and porous soils, or more porous, in 
the case of heavy clay soils. We also expect to get the 
benefit of a heavy manuring with farmyard manure, for 
two or three crops. Artificial manures are in a highly 
concentrated form, and must therefore be used with 
great care by beginners. When the principles of arti- 
