No. 6. DEPARTMENT OF AGRICULTURE. 361 



otherwise the nitrates remain unaltered although the denitrifying 

 organism may be present in abundance. Apropos to this principle 

 the authors hold with Maercker that horse manure is more active in 

 causing denitrification than sheep or cow manure since the former 

 is much richer in assimilable carbon than the latter. 



It is a well known fact that denitrification is particularly active in 

 stable manure, and denitrifying bacteria are especially abundant 

 therein. The admixture of straw also favors the denitrification 

 process in manure was accelerated by the addition thereto of a 

 straw contains an easily assimilable carbon in the form of pentosans. 

 The pentosans which are abundant in coarse manure and straw, fur- 

 nish a much more readily available food to denitrifying organisms 

 than cellulose or fibre. Still more readily assimilable forms of car- 

 bon are found in such compounds as glycerin, citric acid, lactic acid, 

 etc., and Pfeiffer and Lemmermann found that the denitrification 

 process, and an explanation of this has been found in the fact that 

 soluble calcium citrate. 



The loss of nitrogen in the free state in organic infusions seems 

 to be associated with the presence of readily decomposable nitro- 

 genous bodies, such as the am ides. Thus Grinibert ''^found that the 

 colon bacillus, when grown in a solution containing peptones and 

 nitrates, yielded no free nitrogen, but when grown with nitrates in a 

 solution made from beef extract and containing amides there was a 

 considerable loss of nitrogen in the free state. 



The author, therefore, concludes^ that the nitrogen does not come 

 exclusively from the nitrates, but also results from the denitrifying 

 action of the bacillus upon amido principles in the culture medium. 



2. That the evolution of free nitrogen seems to result from the 

 secondary reaction which nitrous acid, formed by the bacteria, exerts 

 on these amido substances. 



It has been seen that one step in putrefaction and ammonification 

 is the production of amido acids and basic amines, and this explains 

 perhaps the rapidity of the denitrifying process in infusions rich in 

 nitrogenous organic matter which are undergoing putrefaction. 



Kinger'^^ showed that when nitrate of soda was mixed with liquid 

 manure (urine) there w^as a decided decomposition of nitrogenous 

 compounds and loss of nitrogen. And in the same connection, T. B. 

 Wood"* found that nitrate of soda when used alone as a fertilizer for 

 oats gave much better results than when used with manure. 



This simply reiterates the former principle that nitrates readily 

 decompose in the presence of an excess of readily assimilable organic 

 matter'. 



