NITEOGENIZED PHOSPHATIC MANUEES. 289 



high in price, the manufacture of sulphate of ammonia was in its 

 infancy, that of superphosphates was just commencing and could 

 only maintain itself with a great struggle in presence of guano ; the 

 preparation of bone manures, although well advanced at the 

 time, was limited in its scope by the poverty of the raw material. 

 Under these conditions, Peruvian guano was the sole regulator of the 

 price of nitrogen and of phosphoric acid on the international 

 market. 



To-day the situation is not the same. The improvement in 

 the condition of manufacture in the nitrate districts enables the 

 concessionaires to flood the European markets at prices which 

 formerly would have been regarded as ridiculous. The production 

 of sulphate of ammonia in gasworks pursues an ever-increasing 

 progress. The exploration of the Pacific Ocean is always discover- 

 ing new islands of phosphatic guano. Enormous deposits of 

 phosphates have been discovered. Finally, blast furnaces furnish 

 the farmer with large quantities of phosphoric acid in basic slag. 

 The 2 or 3 per cent of potash supplied by Peruvian guano is 

 largely replaced by Stassfurt salts, Aschersleben salts, etc. This 

 abundance of manure is very reassuring as regards the future, and 

 the near exhaustion of the phosphatic guanos may be regarded 

 without apprehension. 



But it is not so as regards nitrogen, which only forms a part 

 of guano. For however important may be the resources of the 

 farmer from this point of view, and although he now only utilizes 

 human excreta to a slight extent, nitrogenous manures are none the 

 less the dearest. The discovery of Hellriegel of plants capable of 

 fixing atmospheric nitrogen through the intervention of certain 

 bacteria, now enables the farmer to economize on nitrogenous manure. 

 Eumpler quotes a rural farm which collects 40 tons of beets to the 

 hectare (16 tons to the acre) with a very high percentage of sugar, 

 and using only a small amount of nitrate, by ploughing in green 

 manures [vetches (tares)] and completing them by a strong ap- 

 plication of superphosphate. Green manuring completed by a 

 good dose of phosphoric acid, potash and lime, forms the manure 

 of the future. It is likely to revolutionize all the present-day systems 

 of farming by freeing the farmer from paying tribute to exotic 

 nitrogen. In any case it holds the key to the solution of the ex- 

 haustion of guano question. 



Fish Guano. — Historical Bevieiu. — The sea is an inexhaustible 

 store of fertilizing matter. Independent of its own richness, it is 

 incessantly receiving organic and mineral matter removed from the 

 soil or detached from the mountains bv the rain of storms. More- 

 over, it receives the human excreta which civilized towns run mto 

 the rivers. All these materials contribute to maintain the marvel- 

 lous fertility of the sea. For many years the sardine fishing has. 



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