260 
FERTILIZERS. 
rect application of fertilizers. The time, however, has come when more attention is required 
to lands in pasture. 
10. Guano. 
The excrementitious matter of birds, in consequence of their peculiar structure, furnishes 
a mixture of substances rich in all those which are active in promoting vegetati<-w : it is the 
richest of fertilizers, under favorable circumstances. The history of guano is intcicsiing, par¬ 
ticularly so if taken in connection with the places of deposit. To us, who inhabit a country 
upon which rains never fail, in their season, it is a matter of surprise, when we learn, for 
the first time, that there are countries where it never rains. It is in those countries that the 
guano is found. The birds, which are large and numerous, and which subsist upon fish, have 
inhabited the islands, upon or near the main coast, from the remotest time ; consequently, during 
the centuries which have elapsed, there are accumulations of guano to a vast extent. It is the 
most highly animalized substance, being, in reality, derived entirely from animal substances; 
accumulating slowly in thin layers, time is furnished for its partial drying, otherwise, if it was 
produced in large heaps, it would heat by fermentation, and prove nearly worthless. Guano 
is composed of the following elements : 
Organic matter,. 56*00 
Phosphates of lime and magnesia,. 26*00 
Carbonate of lime,. 6*00 
Salts of soda, . 10*00 
Salts of potash,. trace. 
Silicious matter, . 2*00 Johnston. 
The ammonia is variable ; in the Ichaboe guano it does not exceed 6 or 8 per cent. From 
the nature of animal matters, it follows that ammonia, which is essentially volatile, must be lost 
in all the changes which this substance undergoes, spontaneously ; and hence the varieties, as 
those from different localities will vary in the amount of ammonia which they contain, and even 
will vary in samples from the same place. For this reason, too, the composition which has 
just been stated does not fully represent the condition of guano, as it reaches our shores : oxa¬ 
late, carbonate, phosphate and sulphate of ammonia should be added. The carbonate of am¬ 
monia is volatile, but the sulphate is fixed. These are important substances, and being soluble, 
act at once upon vegetation. To determine the presence of ammonia in guano, add quicklime 
to a sample, when, if present, it will be exhaled in the peculiar pungent fumes, known to all 
persons. The most economical quantity, for an acre of land, varies from three to five hundred 
pounds. It is one of the peculiarities of this substance that, if applied in large doses, it injures 
rather than benefits the crop ; and, indeed, it is so active that seeds should not be enveloped in 
it at all, as it destroys, or is very liable to destroy their vitality. Many failures have occurred 
in the use of guano ; they have arisen from too free an application, and also from drought. A 
dry season is unfavorable to the employment of it; as, in that case, it is not dissolved, and 
