i8 
Garden Work 
NITRATES 
This class of manure can be applied in many forms, 
but the two principal forms are nitrate of soda and sulphate 
of ammonia. Although supplying the same food substance 
to plants, they should be used in different ways, on different 
soils, and for different reasons. Why is this? Nitrate of 
soda is in such a form as that, when simply dissolved 
in water, it is at once available as plant food, whereas 
sulphate of ammonia has to be changed slowly into a 
nitrate before it is available to the plant as food. We 
know that flour contains the elements of food necessary 
for man, but we do not make a meal of it in the form 
of flour. It is first made into bread, and then it is in a 
suitable condition for our use. So it is with sulphate of 
ammonia. The little bacteria in the soil take hold of it, 
and change it into a nitrate. Now, what does this teach 
us about the application of these two important manures? 
In a wet season you must not use the more soluble nitrate 
of soda. A little rain would dissolve it, but a large quantity 
of rain would not only dissolve it, but would wash it 
through the soil into the subsoil, beyond the reach of 
plants, or perhaps into the drains, where it would be 
entirely lost. In such seasons it is better to use sulphate 
of ammonia, which has to be changed into nitrates before 
it can be utilized by the plants as food. As this process 
goes on slowly, the plants are able to make use of the 
nitrates as food before they are washed out of the soil. 
On heavy (clay) soils, there is less fear of the nitrates 
being washed out. Even if the sulphate of ammonia does 
dissolve, the soil being saturated with moisture, the super- 
