258 
FERTILIZERS. 
abounds in the soil, it need not be added, though in its ordinary state, it is quite insoluble; 
but, by the use of lime, may we not always obtain it in sufficient quantity for use of vegetation, 
without a special addition to the soil 1 and I think experience proves the economy of the use 
of lime, and has a preference to Liebig’s patent silicate of potash and soda, which has created 
some noise, and has been recommended on the authority of his name. 
5. Of Mixed Saline Substances. 
I have spoken of the simple salts, as they have been used separately and alone. As plants 
require several elementary bases, in combination with acids, it seems more agreeable to the 
nature of the case to add mixtures of the salts of soda, potash and lime, as then the general 
wants of vegetation will be far more likely to be met and supplied. Thus, if the sulphates of 
lime, soda, magnesia and common salt, or the nitrates of potash and soda, with common salt 
and gypsum, were mixed and used, the result would be better than the use of either singly. 
There are various modes or proportions which may be observed in combining them, which will 
meet the wants of the crops : these proportions may be determined by consulting the analyses 
of the plants, which are given in books upon this subject. Indeed there is no other source 
from whence our rules for the formation and application of fertilizers can be derived. These 
mixtures may be used as top dressings, or they may be incorporated with the compost or ma¬ 
nure heap. But in general these very soluble fertilizers, as the nitrates and sulphates of the 
alkalies, are better adapted to growing crops, and to be used as top dressings. Top dressings 
may be applied in two states, either in solution in water, or in powder, and sown broad cast. 
For the former, the solution should be extremely dilute, scarcely or only slightly saline : in 
the latter state the powders require intermixture with gypsum or ashes, in order to secure an 
even distribution over the field, and also to prevent a concentrated effect upon the different 
parts of it. When concentrated they have an effect which is described by the term burning— 
a term expressive of the apparent action of too high a temperature. Instead of ashes, which 
has been often recommended for mixing with saline matters, bone dust, when it is possible to 
procure it, will be equally good or better than ashes, or if the ground mineral phosphate can 
be procured, it wdl be quite as good as either. It is now ascertained that the latter may come 
into use to a limited extent, as it is now proved to exist in veins in primary rocks. The mine¬ 
ral called eupyrchroite, which I discovered at Crown Point, forms a vein varying in width from 
two to six feet, and hence may furnish a large amount of native phosphate of lime, in the same 
condition as it exists in the soil. This substance is less soluble than bone dust, and hence its 
immediate effects may not be so striking as to arrest the attention of the farmer at once, yet it 
will last longer and be more durable. Immediate effects are often desirable, and even neces¬ 
sary, but when farmers have employed a fertilizer which is common in the constitution of all 
plants, they need not regard the substance as wasted or lost, even though the first effects upon 
his crops are not very striking. Thus common carbonate of lime, when sown upon his fields, 
may not produce an increase in the value of his first crop, yet lime is one of the essential con¬ 
stituents of all plants, and must exist in the soil : so especially the phosphate of lime is still 
