16 



tion of the fertilizers applied before the nutrient substances they contain 

 become insoluble. The humus keeps them in a soluble condition, which 

 is an argument for the use of barn manure, or the plowing under of 

 weeds or green crops, in connection with the use of fertilizers. It acts 

 as a sponge to absorb and hold moisture in low, black soils, which are 

 made up of dead vegetable matter in a state of semi-decay, halfway 

 towards coal a carbonaceous mass of stems, roots, and leaves. Burned, 

 it makes an ashes red, from the presence of iron, having but one sixth 

 the potash to be found in hard-wood ashes. The trouble is, that when 

 dry it takes up water very slowly, and it takes therefore a good deal of 

 rain to moisten it; while, on the other hand, when wet it keeps wet and 

 cold too long for the health of vegetation. Without draining, manure 

 is a waste on such soils. 



Humus* holds a great store of carbonic acid, which decomposes the 

 minerals in the soil, setting free potash and phosphoric acid. It also 

 holds latent nitrogen, sometimes as high as 3 per cent, which is six 

 times as much as in average stable manure. This is made plant food 

 by the application of lime or carbonate of potash. 



Humus is not in itself plant food. It is not necessary for the yield 

 of heavy crops. 



PHOSPHORIC ACID. 



This, the third substance in the three components of a complete fertil- 

 izer, is composed of the element phosphorus, combined with the gas 

 oxygen. The four great resources for phosphoric acid are the mineral 

 called apatite, which contains 92 per cent of phosphate of lime, and is 

 believed by some chemists to be the original source in nature from 

 which phosphate of lime is derived; the phosphatic guanos, which are 

 the product of sea fowls, from which the ammonia has been washed out 

 by the rain; the bones of all animals, and the mineral phosphate rocks, 

 which are the remains of ancient marine animals. 



BARN MANURE. 



Its Composition and Fertilizing Properties. 



The latest analysis made 'of fresh barnyard manure proved to contain 

 the following kind and quantity of elements: 



Water 71.3 



Nitrogen 0.5 



Silica and insoluble mutter 10.5 



Alumina and oxide of iron 0.7 



Lime 0.5 



Potash -. 0.4 



Soda 0.1 



Phosphoric acid 0.5 



Chlorine 0.1 



In about 4,500 pounds of fresh stable manure we should have in it 

 3,208 pounds of water, 22-J pounds of nitrogen, 472-^ pounds of silica, 

 31i pounds of alumina of iron, 22-J pounds of lime, 13^ pounds of mag- 

 nesia, 18 pounds of potash, 4-| pounds of soda, 4-^ pounds of sulphuric 

 acid, 22^ pounds of phosphoric acid, and 4-^ pounds of chlorine. By the 

 composition given it will be noticed that bulk is not what is necessary, 



* Professor Gregory "How to Compound Fertilizers." 



