MIXED FERTILIZERS 43 



will very likely react with some of the sulphates present, 

 so that in the manure heap the ammonia will be partly as 

 ammonium sulphate. In addition to this, as the organic 

 matter is decomposed by bacterial action, a portion of it will 

 form those vague compounds which we call humic acid, 

 which will enter into combination with the ammonia and 

 produce the soluble, dark-brown coloured substance, 

 ammonium humate. Some nitrogen is also present in the 

 amide form. Urea itself is an amide, but is not the only 

 one present. Many other amides are produced by the 

 action of bacteria upon proteins. Amino-acids and peptones 

 are also present. A fair proportion of the soluble nitrogen 

 which exists in the manure heap results from the bacterial 

 digestion of the proteins. Many of the bacteria in the manure 

 heap belong to the class that liquefy gelatine. The liquefac- 

 tion of gelatine is only a special, easily observed case of the 

 peptonization of proteins, and a part of the proteins which 

 have not been digested by the beasts goes into the peptone 

 form in the manure heap. Of the albuminoids in the dung, 

 some are soluble, but most are not merely insoluble in 

 water, but very resistant to all chemical change ; indeed part 

 of the proteins that are passed by the beasts is the residuum 

 of dead bacteria, which needs protracted decomposition. 



The potassium in the manure heap will occur as potassium 

 sulphate and potassium humate. Most of the potassium is 

 soluble, and therefore very easily lost, unless care be taken 

 for its preservation. 



The phosphorus in the manure heap is very largel}' in 

 the form of phosphates, but some part is organic. Although 

 the manure heap is alkaline, and contains lime and ferric 

 hydrate which would normally precipitate all the phosphates, 

 yet in the presence of so much soluble organic matter, iron 

 and calcium are not able to precipitate phosphoric acid in 

 alkaline solution, so that, as a rule, at least one-half of the 

 phosphorus is soluble. 



The calcium present is not in sufficient quantities to 

 appreciably affect the total value of the manure, but it has 

 some action upon bacterial life. It will occur mostly in 



