PROPERTIES OF MANURES 237 



genous manures : farmyard manure and other 

 organo-nitrogenous manures have to undergo the 

 process of nitrification before they become plant- 

 foods. 



Sulphate of ammonia becomes more located in 

 the soil than nitrate of soda — in other words, it 

 is fixed by the soU, and consequently does not 

 distribute itself like nitrate of soda. For this 

 reason it is useful for pot-plants in stoves or 

 greenhouses. 



Sulphate of ammonia is directly absorbed by 

 some plants (see chapter iii.), and is of value 

 in the early ripening of fruits, and in enhancing 

 the colour of flowers. It is also of the greatest 

 use as a dressing after a severe winter ; and a 

 solution of it restores and revivifies faded 

 flowers. 



Ammonium Chloride and weak ammonia are 

 also useful for supplying nitrogen. 



Nitrate of Potash, saltpetre or potassium 

 nitrate contains in a 100 parts : — 



Nitric acid . . . 53 -41 = 13 -8% Nitrogen. 

 Potash . . . . 46-59 



and supplies both nitrogen and potash. It is 

 a useful manure for the growth of many 

 trees. 



