7 i8 



The best guanos that have been found are those on the west 

 coast of South America and the south-west coast of Africa, most of 

 which have long ago been worked out. It is scarcely within the 

 scope of this book to give a historical account of these earlier 

 deposits, or even to enter into any lengthy account of those in 

 existence at the present time. Some of these are nitro-phosphatic, 

 containing from 3 to 13 per cent, of ammonia, and some of them 

 contain as much as 3 per cent, of potash. Other very large 

 deposits are purely phosphatic, containing no nitrogen, or at most 

 a fraction of a per cent. 



Guanos of the nitrogenous class that are imported into 

 England at the present time contain from 3 to 6 per cent, of 

 ammonia, and 20 to 45 or even 50 per cent, of phosphatic lime, 

 excepting those from the Ichaboe islands, on the south-west coast 

 of Africa, and Angamos Island, in Peru, which contain from 8 to 14 

 per cent, of ammonia, and 12 to 30 per cent, of phosphates. These 

 islands annually furnish only small quantities of guano, which con- 

 sists of the fresh excreta of birds, and is gathered every year by 

 the natives. The nitro-phosphatic guanos are scarcely to be found 

 in the market of Western Australia, nor are they likely to be so for 

 some time to come, unless fresh discoveries are made near at 

 hand. The chief supply of guanos sent to the markets of the world 

 is purely phosphatic, and is used for the purpose of making super- 

 phosphates. Of this class there are some enormous deposits in various 

 parts of the world. The guano deposits found on the coast of 

 Western Australia are of this class and are best suited to the making 

 of superphosphates. As a manure, direct, this class of guano, even 

 if used in conjunction with potash and nitrogenous matter, is slow 

 in its action and inferior to bone-meal and not much better, if any, 

 than coprohte mineral phosphate. This guano should be applied 

 in a very fine state to give the best results. At the best these guanos 

 are not the most profitable manures that can be used. The phos- 

 phatic guanos may be applied at the rate of 3 to 9 cwt. per acre, 

 according to the percentage of phosphoric acid they contain and 

 give the best results on soils low in lime. 



XlTKOGENOUS MANURKS. 



The two best nitrogenous manures are sulphate of ammonia 

 and nitrate of soda. They are by far the richest in nitrogen and 

 also the quickest and most certain in their action on crops. 



Some time back the most favoured method of applying nitrogen 

 to the soil by means of artificial manures, was by the use of guanos 

 rich in ammonia. Since these rich guanos have become more scarce 

 in the market, sulphate of ammonia and nitrate of soda have taken 

 their place. 



Sulphate of ammonia is the most concentrated form of nitrogen 

 as a manure, and one of the most active and readily available plant 

 foods. It is much quicker in its action than any form of organic- 



