214 MANURE, ARTIFICIAL 



momacal salts, nitrate of soda, animal matters, &c., are therefore almost always 

 blended together with phosphates, common salt, gypsum, &c., by manufacturers of 

 manures. 



Whilst we thus fully recognise the importance of the presence of ammonia, am- 

 moniacal salts, nitrates, or animal matters furnishing ammonia on decomposition in 

 manures, especially in manures for white crops, we cannot agree with those who 

 estimate the entire value of manuring-substances by the proportion of nitrogen which 

 they contain. 



In a purely commercial sense, nitrogen in the shape of ammonia or nitric acid, or 

 animal nitrogenised matters, is the most valuable fertilising constituent, for it fetches 

 a higher price in the market than any other manuring constituent. 



2. Phosphoric Acid. Next in importance follows phosphoric acid. This acid exists 

 largely in the grain of wheat, oats, barley, in leguminous seeds, likewise in turnips, 

 mangolds, carrots, in clover, meadow-hay, and, in short, in every kind of agricultural 

 produce. Whether we grow, therefore, a cereal crop or a fallow crop, there must be 

 phosphoric acid in sufficient quantity in the soil, or if insufficient it must be added to 

 the land in the shape of manure. 



The proportion of phosphoric acid in even good soils is very small, and as the agri- 

 cultural produce in almost every case removes from the soil more of phosphoric acid 

 than of any other soil-constituent, the want of available phosphoric acid makes itself 

 known very soon. This is especially the case with quick-growing crops, such as 

 turnips, mangolds, &c. The whole period of vegetation of these green crops extends 

 only over 4 or 5 months, and the fibrous roots of these crops are unable to penetrate, 

 like wheat, the soil to any considerable depth. For these reasons, phosphoric acid in 

 some form or other has to be abundantly supplied to root-crops ; and experience 

 has shown that no description of fertilising matter benefits roots so much as super- 

 phosphate and similar manures, which contain phosphate of lime in a state in which 

 it is readily assimilated by plants. 



In artificial manures phosphoric acid commonly occurs in the shape of bone-dust, 

 boiled bones, bone-shavings (refuse of knife-handle makers, turners of ivory, button- 

 makers, &c.), or in the state of biphosphate of lime, purposely manufactured from 

 bone materials or from phosphatic minerals. 



The phosphate of lime which occurs in fresh bones, practically speaking, is insoluble 

 in water. In water charged with carbonic acid, and still more so in water containing 

 some ammonia, it is more soluble than in pure water. On fermenting bone-dust in 

 heaps it becomes a much more effective manure. Such fermented bone-dust is added 

 with much benefit to general artificial manures. 



All really good artificial manures should contain a fair proportion of phosphate 

 say from 25 to 40 per cent., according to the uses for which the manure is intended. 

 Generally speaking, manures for turnips, and root-crops in general, should be rich in 

 phosphates especially soluble phosphates (biphosphate of lime) ; such manures need 

 not contain more than 1 to 1 per cent, of ammonia, and, when used on land in a 

 tolerably good agricultural condition, ammonia can be altogether omitted in the 

 manure without fear of deteriorating the efficacy of the manure. 



3. Potash. Salts of potash unquestionably are valuable fertilising constituents, for 

 potash enters largely into the composition of the ashes of all crops. Hoot-crops es- 

 pecially require much potash ; hence these crops are much benefited by wood-ashes, 

 burnt clay, liquid manure, and other fertilisers containing much potash. 



The commercial resources of potash are limited, and salts of potash have generally 

 been far too expensive to be employed largely in the manufacture of artificial manures. 

 Fortunately potash exists abundantly in most soils containing a fair proportion of clay. 

 Its want in artificial manures therefore is not perceived, at least not in the same 

 degree in which the deficiency of phosphates in a manure would be felt. Of late years 

 however valuable deposits of potash-salts have been discovered at Stassfurt in Prussian 

 Saxony, and have been extensively employed for various industrial purposes, including 

 the preparation of manures. 



4. Soda. Salts of soda are much less efficacious fertilising matters than salts of 

 potash. There are few soils which do not contain naturally enough soda, in one 

 form or the other, to satisfy the wants of the crops which are raised upon them. 

 However, common salt is largely employed in the manufacture of artificial manures ; 

 if it does no good, it certainly does no harm ; and in this country it is one of the 

 cheapest diluents which can bo employed for reducing the expenses of concentrated 

 fertilising mixtures to a price at which they can be sold to farmers. In continental 

 districts common salt proves more efficacious as a manure than in England, where the 

 neighbourhood of the sea provides the majority of soils with plenty of salt, which 

 by the winds is carried landwards with the spray of the sea to vury considerable dis- 

 tances. 



