Food from the Soil 147 



that farmers in America sometimes grow it in alternate 

 rows with wheat, and this is also the only kind of 

 green-manuring commonly practised in England. It 

 is in warm countries, where growth is rapid, that this 

 sort of manuring is chiefly useful ; and in the Azores, 

 yellow lupins are very frequently sown among the corn 

 and ploughed in when it is reaped. 



Lupins are plants which are especially active in 

 dissolving mineral matter; and the same is true of 

 other members of the large family of leguminous 

 plants to which they belong clovers, vetches, beans, 

 peas. Moreover, not only these but other plants 

 dissolve more food than they need for their own 

 immediate use and leave it in the soil, making it 

 easier therefore for their successors to find nourish- 

 ment. 



This, then, is another important service rendered 

 by the wild crops which have grown for ages past on 

 what are now the best soils in the world for the 

 farmer's purposes. Whether these crops be trees, or 

 shrubs, or herbage, they have not only brought subsoil 

 up to the surface, but they have, at least in some 

 cases, dissolved more than they have used, and have 

 left it all ready for the crops which follow to make 

 use of. 



But even this is far from exhausting their very 

 important list of services. Indeed, the most impor- 

 tant of all has yet to be mentioned. 



Animals cannot live either upon mineral matter or 

 upon gases, though they need both, until these have 

 been made ready for them, which they must be in the 

 first instance by vegetables. 



Plants are more independent, for they can make use 



