MANURES, THEIR KINDS AND USES. 43 



tion the gardener may undertake more cheaply at home, 

 and with greater satisfaction. 



Phosphatic fertilizers are especially beneficial to root 

 and bulb crops. 



More or less of the insoluble phosphates may be mixed 

 with and sold in the superphosphate. These have little 

 practical value to the general agriculturist, and none to 

 the gardener. 



During the fermentation of the bone meal in the- ma- 

 nure pile, which is accelerated by the gelatine, soluble 

 nitrogenous organic compounds and salts of ammonia 

 are produced. These act quickly and powerfully as fer- 

 tilizing agents, and render the phosphate more soluble. 



POTASH. 



No vegetable can grow without potash, for it is a con- 

 stituent of every plant. Its presence has been proved to be 

 necessary for the formation of starch in the leaves; and 

 the experiments of Lawes and Gilbert have pointed out 

 that it aids leguminous plants, like clover, in assimilat- 

 ing nitrogen, which they contain so largely. It results 

 in soils from the disintegration of minerals, and is less 

 apt to be absent, particularly in heavy soils, than either 

 nitrogen or phosphoric acid. 



Neither the land of the truck-farmer near a city, nor 

 any other land, which has been, even only moderately, 

 enriched with the dung of domestic animals and accom- 

 panying vegetable matter, needs any special application of 

 potash. If a crop, even of potatoes, fails on such soils, it 

 will be owing either to a deficiency of the more important 

 elements of plant food, or to other unfavorable contingen- 

 cies, as of weather, tillage, drainage, etc,, rather than to 

 a lack of potash. But on light lands frequently manured 

 .with exclusively nitrogenous manures, like fish scrap, 

 Peruvian guano, etc., and cropped with potatoes, or some 



