278 • Bacteria in Relation to Country Life 



The liming of soils. — The periodical liming of soils is 

 necessary because of the gradual removal of the lime 

 from the surface layers in the manner just noted. The 

 analysis of drainage waters shows that every soil loses 

 its lime more or less rapidly, the amount removed being 

 increased by the application of organic materials, 

 especially of animal manures and of green-manures. 

 Furthermore, the operations of tillage, which, by better 

 aerating the soil and by conserving its moisture, stimu- 

 late the growth of decay bacteria, increase the losses of 

 lime from the soil. The removal of lime from the soil 

 is, therefore, not only absolutely but also proportionately 

 greater in well-tilled lands abundantly provided with 

 humus. The action is also reciprocal, since the addition 

 of lime to the soil favors the growth of most soil bacteria, 

 while the more intense growth of the latter leads to the 

 rapid formation of products that hasten the removal of 

 lime from the soil. In one way, therefore, it would be 

 proper to say that the more the soil is limed the more 

 lime it will require, provided, always, the proper por- 

 portion of organic matter is maintained. 



Losses of lime. — Greater or slighter losses, then, of 

 lime as bicarbonate occur from all soils. Lime may, 

 however, be lost from soil in other ways. It has already 

 been noted under nitrification that, in the change of the 

 humus-nitrogen to nitrate, considerable quantities of lime 

 are used to combine with the nitric acid produced by the 

 bacteria. The nitrate of lime thus formed is soluble like 

 other nitrates and distributes itself freely in the soil- 

 water. When not taken up by the growing crop, the 

 nitrate of lime or magnesia ultimately finds its way 



