VI.] GREEN MANURES. 63 



its accuracy. Many established local customs repre- 

 sented as theoretically erroneous, have been proved 

 to be correct by a more perfect knowledge of the 

 agencies which are in operation, and it is by no means 

 improbable that similar cases may yet come under 

 notice. 



122. Green manures consist of crops grown for 

 the express purpose of being ploughed into the land 

 as manure. It is, in fact, manuring the land with 

 vegetable matter. As plants draw nourishment from 

 the atmosphere, the crop so grown for manure returns 

 to the soil more than it took from the soil, and so far 

 it enriches it. But whilst the leaves are thus accumu- 

 lating stores of fertility from the atmosphere, the roots 

 are actively searching for nourishment from the soil, 

 and storing this within them. Hence, when the crop 

 has been fully grown, a large quantity of plant food 

 has been gathered together, and this accumulation or 

 store of food is buried in the soil, ready for helping 

 the growth of the succeeding crop. This is no loss of 

 labour, for it is copying from the example of nature. 

 We have noticed (10) that when first the surface of 

 a rock has been broken into soil, some of the lower 

 forms of vegetation fix themselves there. These can 

 exist under greater difficulties than more highly organ- 

 ized varieties, and they act as pioneers, preparing the 

 way for higher and more useful varieties. They gather 

 from the atmosphere the elements of organic matter, 

 and having organized these bodies, the plant dies, and 

 leaves its organic matter in the new soil. The soil is 

 now prepared for a better variety of plant, and it, in its 

 turn, accumulates still larger supplies of organic mat- 

 ter. These having done their work, die, and so the 

 work of enriching the soil goes on. This is green 

 manuring, as true in character as any we can carry 

 out. 



123. Rye, mustard, lupine, buckwheat, 

 vetches, Italian rye-grass, and clover are crops 



