^yS- AGRICULTURE OF- MAINE. 



be created in the soil as promote the formation of ammonia, and 

 its subsequent change into nitrous and finally nitric acid, in 

 which latter form plants actually take up most of their nitrogen. 

 These changes are all promoted to a high degree by carbonate 

 of lime. 



Certain of the legimiinous plants which gather nitrogen from 

 the air will thrive on exceedingly acid soils. Typical illustra- 

 tions are furnished by the serradella and certain of the lupines. 

 The cowpea, soy bean and vetch will thrive well on soils which 

 are moderately acid, whereas clover and alfalfa require soils 

 which are more nearly neutral, slightly acid, or perhaps slightly 

 alkaline. It is not known, nor does it matter, whether the liming 

 is beneficial to the clover and alfalfa in such cases entirely 

 apart from its effect on the micro-organisms which cause the 

 nodules to develop on their roots, and which enable them to 

 secure nitrogen from the air, or whether liming is vital to the 

 micro-organisms and hence, indirectly, to the plants. The 

 important fact is that many soils in New England have become 

 actually clover sick and alfalfa sick to such an extent that these 

 plants either die or produce only a partial crop until the land is 

 limed, entirely regardless of how generously the crop is fertilized. 



EFFECT OF LIME ON PLANT DISEASES. 



There is no longer any doubt about the influence of lime in 

 connection with many plant diseases. In Porto Rico, Gile found 

 that the heavy liming of sandy soils interfered with the pine- 

 apples' ability to secure the necessary amount of iron, with the 

 result that serious chlorosis of the plants developed. Treat- 

 ment of the soil and leaves with iron salts corrected the condi- 

 tion, for the iron was then assimilated sufficiently to meet the 

 plants' requirements. 



Heavy liming in certain sections of the Connecticut Valley 

 in Massachusetts and Connecticut has sometimes led to the 

 development of the so-called "tobacco root rot." 



In Germany a disease of oats known as *'dry spot" has been 

 found, occasionally to follow heavy liming, and a disease or 

 physiological disturbance showing similar effects has been noticed 

 by the writer in occasional years in Rhode Island. In the latter 

 case, its occurrence seemed to hinge also upon the weather con- 

 ditions, for it was noticeable only in occasional seasons. 



