142 MEADOWS AND PASTURES 



may see the soil become richer and richer year by year. 

 Even when the legumes are each year removed from the 

 land the soil may accumulate nitrogen. Hunt gives an 

 instance of a soil area at Lupitz which bore 28 successive 

 crops of lupines which were removed and nothing sup- 

 plied but kainit. Notwithstanding the large amount of 

 nitrogen removed from the field it was found to make 

 a steady gain in soil nitrogen. The conditions that favor 

 the useful bacteria are that the land shall be moist but 

 not wet, shall have air entering it somewhat freely, and 

 shall be alkaline, not acid, in its reaction. The presence 

 of a considerable amount of carbonate of lime in the soil 

 is very favorable to these nitrifying bacteria. It is clear 

 that they can do nothing in a waterlogged soil, since it 

 has in it no air. It has been abundantly proved that sour 

 soils are unfriendly to legumes and unfriendly to their 

 allies, the bacteria. Indeed it may be true that the one 

 reason why sour soils are unfriendly to legumes is that 

 the bacteria will not increase there. 



Carbonate of Lime and Legume Growing. It is very 

 noticeable that in regions with much carbonate of lime in 

 the soil wild legumes are abundant. In the semi-arid re- 

 gions, where soils are usually rich in lime because it has 

 never been leached away, one often finds a great number 

 of species of legumes. Such soils are so well filled with 

 many kinds of bacteria that few legumes growing on 

 them need inoculation in order to start out vigorously as 

 soon as sown. In other soils, where lime is wanted, one 

 finds few or no legumes at all. I was recently engaged 

 in studying certain mountain soils in California and dur- 



