103 



isms being mutually dependent upon each other. Since ni- 

 trogen is the costliest form of plant food obtainable, and 

 since many of the commercial forms of nitrogen are either 

 inaccessible to, or beyond the means of, many of the farmers, it 

 will be readily seen that this system of green manuring, 

 which provides a means for the collection of this valuable 

 element from the atmosphere and a medium through which 

 it can be stored up for the use of subsequent crops, is of 

 the highest importance and utility to the farmer. Ex- 

 periments conducted at this station several years since, 

 showed that a crop of pea vines, grown on a sandy loam, of 

 only moderate fertility, contained the following amounts 

 of phosphoric acid, potash and nitrogen (calculated from 

 actual analyses) per acre. 



'a 



Phosphoric Acid. 

 Potash 



Nitrogen 



39.05ft 



88.79" 



115.54" 



6 90 



13.12 



7.70 



45.95.1. 2 30 

 101.91 1 02 

 123.24 21 56 



The values are calculated according to our scale of fer- 

 tilizer valuations, and it will be seen that the value of the 

 nitrogen alone, exceeds that of a ton of ordinary complete 

 fertilizer, while the nitrogen is equivalent in amount to that 

 contained in 1750 pounds of cotton seed meal, though this 

 crop was considerably above the average yield. 



In addition to the advantages derived from turning un- 

 der a crop which has a peculiar adaptability to securing 

 plant food from the air, and from the soil and soil water, 

 such a crop supplies an immense mass of organic matter 

 to the soil. 



This vegetable matter on oxidation and decomposition, 

 gives off large amounts of gaseous matter of which carbonic 

 acid forms the chief proportion, and this last substance is 

 highly instrumental, especially when in a state of solution, 

 in the breaking up and dissolving the chief constituents of 

 the soil. 



