DECOMPOSITION OP ORGANIC MATTER IN THE SOIL 327 



with those of Marchal the former have obtained results in soils, while 

 the latter's work was with solution cultures, the apphcation of whigh 

 to sou conditions is not always permissible. In point of fact the am- 

 monifying efficiency of organisms is greater in sandy soil and possi- 

 bly in others than in solutions, as Lipman and Burgess have obtained 

 a transformation of 41.98 per cent of peptone in nitrogen and 36.06 

 per cent of bat guano nitrogen into ammonia by Sarcina lutea aiid 

 B. mycoides, respectively, in twelve days at temperatures between 

 27° and 30°., while Marchal obtained similar transformations in 

 thirty days at 30°. in albumen solutions. 



It is also of interest to note that investigations with soil fungi have 

 revealed the fact that certain species are even more efficient am- 

 monifiers than B. mycoides. McLean and Wilson, Waksman, Cole- 

 man and Kopeloff have worked with organisms Hke Trichoderma 

 koeningi which is capable of transforming more than 50 per cent of 

 the nitrogenous material added in such experimentation. 



Nitrification. Experimental Study. — The terra nitrification refers 

 to the oxidation either of ammonia or of nitrites to nitrates. In a 

 broader sense nitrification may be defined as the production of nitrates 

 from decomposing organic matter. Saltpeter or niter, the .terms 

 formerly applied to potassium nitrate, possessed, for a long time, a 

 peculiar interest because of its relation to gunpowder. Whether it be 

 true or not that gunpowder was known to the Chinese before the be- 

 ginning of the present era, there is no doubt that for several centuries 

 it played an important part in the political and economic history of 

 Europe. The large quantities of gunpowder consumed in the almost 

 incessant wars created a steady demand for saltpeter that was not 

 readily met by the saltpeter refiners of India, Hungary and Poland. 

 European nations, particularly France, were therefore thrown on their 

 own resources and were forced to develop the domestic production of 

 saltpeter. The industry came under government control and experts 

 were appointed to study the so-called saltpeter plantations and the 

 conditions affecting the appearance and increase of nitrates in com- 

 post heaps and in the soil. Much knowledge was thus gained about 

 nitrification even though it was not suspected that living organisms 

 were concerned in the process. 



With the rapid development of chemistry in the latter half of the 

 eighteenth century a nearer approach was made to the understanding 



