334 Bacteria in Relation to Country Life 



more effectively these undesirable activities in the soil 

 and the manure heap. They may also teach us how to 

 encourage them on occasions when it is desired to hasten 

 as far as possible the decomposition of offensive waste 

 materials. 



SOLUBLE NITROGENOUS SUBSTANCES MADE INSOLUBLE 



Soils kept bare during a part of the summer rapidly 

 accumulate a store of nitrates that are liable to be 

 leached into the subsoil and lost to succeeding crops. 

 In order to obviate this loss, it has been proposed to 

 grow crops like mustard, buckwheat, or millet to take 

 up the nitrates. The nitrogen, it was thought, could be 

 subsequently recovered by the turning under of these 

 crops as green-manures. 



In practice, this has often been found unsatisfactory, 

 because the nitrogen thus laid fast in the green-manure 

 did not again become available rapidly enough to satisfy 

 the demands of the succeeding crop. ^ somewhat 

 analogous condition is found in the manure pile. The 

 nitrogen of the liquid excreta is one of the most valuable 

 constituents of manure, because of its almost immediate 

 availability to growing crops. Hence, manure rich in 

 liquid excreta, in other words, manure rich in available 

 nitrogen, is more desirable than similar manure poor in 

 available nitrogen. 



It happens, however, that in the storing of manure, 

 the proportion of insoluble nitrogen compounds is in- 

 creased, while the proportion of the soluble nitrogen 

 compounds is decreased. Mention has already been made 



