HOW TO PREPARE AND FERTILIZE LAND 1 5 
additional value of supplying humus, 
which lightens the soil, increasing its 
power to hold water. It also assists in 
liberating the mineral substances in the 
soil. If the manure is coarse, it should 
be rotted to increase its availability 
before applying. There are three elements 
necessary to supply to the soil: nitrogen, 
potash and phosphoric acid. Farm ma- 
nures supply all of these, but not always 
in the proportion needed. 
Commercial fertilizers can be bought 
and applied separately or in combination. 
It must always be remembered that they 
are very powerful and should never be 
placed in contact with roots or seeds, but 
should be mixed with the soil. 
Nitrates stimulate the vegetable system 
and tend to produce dark-green foliage. 
The application of too much nitrogen has 
a tendency to make the plant “run to. 
leaves” at the expense of flowers and 
fruit. A lack of nitrogen is shown by 
weak growth of a yellowish-green colour. 
Nitrate of soda and sulfate of ammonia are 
