THE POSSIBILITIES OF ARTIFICIAL MANURES IN FORESTRY. 257 
but it must not be applied too closely to the roots, nor when 
they are in an active condition. It is best applied in winter, 
so that the chlorides may be dissolved and washed into the 
deeper layers of the soil before root-growth commences. Under 
certain conditions, refined potash salts, such as sulphate of 
potash, may be used in place of kainit, especially when the 
soil inclines to be heavy. 
Lime.—This is an important constituent of the soil, especially 
as regards the nourishment and well-being of trees. Its use 
is two-fold; first as a direct food material, and second as an 
indirect agent in the nutrition of trees. It is difficult to say 
which of these is the more important, but certainly lime 
in some form or other is quite indispensable. If the facts were 
known, probably most of our forest soils would be found to be 
more deficient in this important constituent than is at present 
supposed. Lime, it seems, should be present to the extent of at 
least -25 to ‘30 per cent. of the dry substance of the soil, and 
it is questionable if there is always even that amount available 
for the trees. In its direct action lime exercises a great influence 
on the chemical and physical properties of the soil. It pro- 
motes the disintegration of humus, and its conversion into 
ammonia and subsequently into nitrates, since the nitrifying 
bacteria act with greater energy when lime is present. In mossy 
and peaty soils nitrification is at a standstill, on account of the 
excess of humous acids, which prevent the action of these beneficial 
organisms. ‘The presence of lime neutralises the humous com- 
pounds and promotes the action of the bacteria. Its presence 
also prevents the formation of moor-pan and other unfavourable 
conditions arising from excess of humous acid. Further, these 
same humous acids, which are neutralised by the lime, prevent 
the proper absorption of water by trees. There are many other 
indirect advantages derived from the application of lime to the 
soil, into which we cannot go further here. 
There are various forms in which lime may be added to the 
soil. They differ somewhat as regards the rapidity and duration 
of their action, but, provided it is used with discretion, there does 
not seem to be much material advantage in any one form over 
another, so long as the soil is enriched with lime. 
The idea in forestry hitherto has been that, apart from a 
certain breaking up of the soil, and possibly drainage, nothing 
more was required for the growth of trees. In the foregoing 1 
