524 QUEENSLAND AGRICULTURAL JOURNAL. [1 Dec., 1901. 
ship's rigging and sails, and knew every manwuvre by heart, but had never 
seen the sea or touched a rope on a ship ? 
The same thing applies to the lad who wants to be a farmer. He must use 
the tools of trade, as well as look on. So what you should do is, if possible, to 
get hold of a bit of garden ground to begin with, and learn how to work the 
soil, how to sow different seeds, how to distinguish weeds from plants, &c. You 
might, by and by, make small experiments with manure, especially if the soil be 
not too rich. A rich soil will not give you so many opportunities for this as a 
poorer one. 
Now, we will get on with the improvement of our exhausted toil. The third 
method of helping to restore its fertility is GREEN MANURING. By green manuring 
—that is, growing a crop of cow peas, rape, lupines, or some crop of the pea or 
bean family which grows quickly, and ploughing it in before it attains 
maturity—a large quantity of the needful or@antc matter is returned to the soil. 
Without Humus, the soil becomes lifeless and cannot exert any great influence 
on plant life, and, furthermore, it will not assist the action of fertilisers. So 
that the necessary ingredient must be supplied by either farmyard manure or 
green manure. But the latter will not be entirely successful unless there is a 
proper supply of organic and mineral manures, such as potash, lime, and 
phosphoric acid, in the soils on which the crops are grown. The legumimous 
plants I have mentioned furnish a large supply of that very necessary element 
—nitrogen. That supply they obtain from the air, and they give it up to the 
soil in different quantities, according to the crop sown. 
Thus the amount of nitrogen drawn from the air by the green crops and 
released in the soil varies from 53 Ib. to 134.1b. per acre. If a leguminous crop 
is ploughed in green, the amount of nitrogen resulting from it is equivalent to 
a good dressing of nitrogenous manure—such as nitrate of soda, sulphate of 
ammonia, or farmyard manure. Even if the leaves are used for fodder, yet the 
roots and stems remaining in the ground contain enough nitrogen to ensure a 
full yield of cereals or other plants. The nitrogen is contained in the little 
nodules or swellings on the roots of the plants, and these are not always easy 
to find. When you pull up a plant violently, you probably leave most of them 
in the ground. But if you take up the plant carefully and remove the soil 
gently, you will find them. If you find no nodules then there is no nitrogen 
taken in by the plant, and the soil is as poor as before, except for the humus 
produced by the plant when ploughed in. When a green crop is allowed to 
grow—say to the flowering stage—it has gathered up quantities of plant food 
from the air, the soil, and from the water of the soil. When the crop is buried 
the whole of this collection is returned to the soil, which is thus made fertile. 
Besides the nitrogen, there is a large quantity of carbonic acid, which dissolves 
other plant food and makes it available for the succeeding crop. 
Even sandy soils which will not retain water have been so altered by 
regularly ploughing in green crops that they will afterwards retain both water 
and manure. 
Most people think that green manuring is a modern idea, but in a sense 
it is as old as the early days of agriculture. You remember what | told you 
about fallowing (5th Lesson)—viz., that it is a means of cleaning the land of 
weeds. What becomes of the weeds? They are ploughed under as often as 
they appear, until at last they are banished. Now, this was nothing more or 
less than green manuring. ‘The rotten weeds turned into humus, and so helped. 
to enrich the soil. But our scientific men have discovered that certain plants 
collect more nitrogen than others, and hence are more valuable when buried. 
The very best plant for the purpose is the white lupine, because it roots 
deeply, grows quickly, and bears a quantity of leaves. In this State, however, 
the cow pea is used, particularly on the sugar plantations. 
The velvet bean is a very good plant also, as it produces an enormous 
amount of organic matter. 
There is one danger about green manuring which it is well you should 
know. Ifa drought comes on immediately after ploughing in a heavy green 
