No. 4.] NITROGEN AND FERTILITY. 183 



Decomposition of Manure. 



The freshly voided manure of animals contains an enor- 

 mous number of many varieties of bacteria which act upon 

 the nitrogen compounds. These are very active in breaking- 

 down the complex materials left in the processes of diges- 

 tion, and changing the nitrogenous materials into forms 

 available to growing plants. Hence it happens that in the 

 manure heap the organic compounds are being very rapidly 

 broken up. The nitrogen compounds are changed partly 

 into free nitrogen, which is lost, and partly into ammonia. 

 This change to ammonia is very noticeable, and frequently, 

 because of the rapidity of the fermentation, the small amount 

 of acid developed is not sufficient to retain the ammonia, 

 and the very familiar odor of ammonia escaping from the 

 manure heap results. It is of course important that these 

 destructive changes be controlled so far as practicable, and 

 the resulting ammonia preserved. The most obvious chem- 

 ical treatment would be to sprinkle the manure heap with 

 an acid. This results in fixing the ammonia and restraining 

 the action of the bacteria. Sulphuric acid has been fre- 

 quently employed for this purpose, but the method is some- 

 what expensive both in material and labor. Chemicals, such 

 as acid phosphate, land plaster, kainit, muriate of potash, 

 etc., have been used with more or less success. In the case 

 of the acid phosphate and the potash salts, the phosphoric 

 acid and potash which these materials carry will of course 

 be available for the growth of plants when the manure is 

 applied to land. It is doubtful, however, if these materials 

 can be advantageously applied, except perhaps in the han- 

 dlino; of hen duns;. 



In addition to the destructive bacteria, there are the con- 

 structive ones, which nitrify the ammonia so as to make it 

 available for plants. Apparently this nitrification does not 

 begin until the organic iiitrogen has been almost wholly 

 broken up into ammonia, and this ammonia is either united 

 with acids or has been lost in the air. The nitric bacteria 

 are so extremely sensitive to aiumonia that they cannot ])e- 

 gin to form nitric acid until ammonia gas has entirely disa})- 



