142 



A reference to the table showing the average 

 composition of bones will explain their powerful 

 action upon vegetable organism ; for they not only 

 contain some of the most essential inorganic plant- 

 constituents, such as phosphoric acid, lime, and 

 magnesia, but also contribute greatly to the develop- 

 ment of the plant by the large quantity of organic 

 matter they contain, nitrogen alone amounting to 

 over 5 per cent. Its effect in so largely increasing 

 the outturn of all nitrogenous food-stuffs, especially 

 cereals, is therefore due partly to its supplying 

 the soil with phosphoric acid, the chief mineral 

 plant-food required by the seed, and partly to 

 the large quantity of ammonia the plant derives 

 from it in addition to that obtained from the 

 atmospheric air. The amount to be applied 

 to an acre will depend upon the means of the 

 farmer ; but generally one to two tons of bone- 

 dust at first, and then an addition of half a ton 

 every tenth year, will give the best results, for 

 it must always be remembered that the more 

 liberally the soil is treated, the larger will be 

 the returns. 



LIME. 



One of the most important and extensively-used 

 mineral manures is undoubtedly Lime. Properly 

 speaking, it can scarcely be called a manure, 

 in the narrow sense of its meaning, as the chief 



