THE TURNIP AS A MANURE." 193 



from the subsoil. If their decomposition took place 

 in the open air, many of the most valuable elements 

 of the former would be lost ; but by ploughing them 

 in, they are absorbed by the soil as they are disen- 

 gaged. The consumption of turnips on the land 

 where they were grown, by feeding them to sheep, 

 is well known to promote fertility; still it is an 

 open question whether, if ploughed in, they would 

 not have a more beneficial effect upon the soil. 

 They gain nothing by passing through the sheep, 

 but rather lose ; for the animal requires their nour- 

 ishment to sustain him. AVhether this would be 

 as profitable as to feed them to sheep, when the 

 return from the mutton and wool is considered, we 

 do not pretend to say, but only to call the attention 

 of the cultivator, who has in his mind merely the 

 fertilization of his land, to the principle involved. 



The soil of the forest shows the efiect of natural 

 green manuring. It is continually dressed by the 

 fall of the foliage ; and, notwithstanding the growth 

 of the tree, the soil gains by the crop, because the 

 leaves contain organic substances derived from the 

 atmosphere, which decompose and escape slowly on 

 account of the shade of the forest. The crops prin- 

 cipally used for artificial manuring are the vetch, 

 buckwheat, rye, turnips, red clover, white lupines. 

 These are adapted to various soils in their several 

 conditions. 



The vetch and white lupine are adapted to all 

 17 



