156 QUEENSLAND AGRICULTURAL JOURNAL. [lL Mar., 1902. 
the haulms, which in consequence had grown to an immense size at the 
expense of the tubers. Thus you see that, if you have no knowledge of the 
effect produced by fertilisers, you may not only waste money but injure your 
crops. What are the functions of potash in the soil? What does it do for 
plants? There is a large quantity of potash contained in most soils when the 
original rocks have been decomposed, and in their remains the potash is present 
in an insoluble form, but much of it is in such a form that it is dissolved by 
water, and so reaches the plant, and some is acted upon by acids which come 
from the plant roots. It is mainly in the case of land which gets little 
manure, and when the rocks only supply a very small quantity of potash, that 
its application to the soil is advantageous. The potash assists in making the 
nitrogen of the soil available as plant food. Have you ever noticed how well 
corn grows on the spots on newly-cleared land where heaps of timber haye been 
burned? The reason is that the potash contained in the wood ashes has 
assisted the action of the nitrogen, which has thus been made available for the 
corn plants in super-abundant quantity. The soil on such spots is always 
moister than the surrounding soil. : 
The plants most benefited by an application of potash are beets, potatoes, 
clover, cabbages—all leafy plants, you notice. Protessor Storer writes: “It 
appears, indeed, that we may say, Use phosphates for turnips and such like 
roots, POTASH FOR LEGUMINOUS PLANTS, and active nitrogen for grain. 
Many of our scrub soils are deficient in potash, so are light sandy soils, 
but as clay increases in a soil so does the potash. It is not good to add potash 
to a very heavy clay soil, therefore. It does more harm than good by makin 
the soil more impervious. But, as I told you before, one of the functions 0 
lime added to a soil is to render it more friable and easier to work, so that, 
if potash is in excess in a clay soil, a plentiful addition of lime will overcome 
its unfavourable effects. But wherever potash is used there must be effective 
drainage, or all its good effects are destroyed. 
What is the effect of applying a phosphatic manure? First, consider 
bone-ash. This is dissolved (probably) by shouted water in the soil, and 
then is conveyed directly to the plant. It is also probable that the solution is 
first decomposed by compounds of iron or of alumina in the soil, and that the 
phosphates of these minerals are dissolved either by carbonic-acid water or 
by the acids of the roots, and so are conveyed to the plant. 
Next take superphosphate. When it is applied to the soil, the moisture 
dissolves the soluble phosphoric acid which soaks into the earth. The earth 
holds carbonate of lime, and this substance with iron and alumina arrest 
it. Now, this phosphoric acid rendered soluble is far finer than the finest 
bone-dust, and is distributed evenly throughout the soil, consequently the root 
crops get a continuous supply, and superphosphate is then infinitely superior 
to bone-meal or bone-ash. 
When you intend to use superphosphate, first pause and consider whether 
there is a sufliciency of lime in the soil. If there is not, you will do harm 
instead of good by its use, in consequence of the soluble phosphoric acid not 
being precipitated quickly enough. There should be enough lime to precipitate 
the acid fairly quickly, and time must be allowed for that precipitation. 
IT will close this lesson with a few remarks on how and when to fertilise. 
In the next book you will be shown how to start a farm; how to deal with it in 
the matter of drainage; what crops to grow; when, where, and how to grow 
them ; what implements, farm buildings, and stock are required on the farm, 
aud many other matters which need to be known to make you a successful 
armer. 
The farmer should bear in mind the particular purpose to which an 
artificial fertiliser is to be applied, since neither all trees nor all crops take 
kindly to the same kind of food. There is as much difference, comparatively, 
in the food of the different members of the vegetable kingdom as there ism 
that of the animal. A horse will not eat flesh, nor a dog hay; neither will all 
trees flourish on the same nutriment. 
