VEGETABLE SUBSTANCES AS MANURE. 187 



erately a second time, and then presents the ap- 

 pearance of garden mould, and equals farm-yard 

 manure." 



One of the most economical methods of applying 

 vegetable matter to the soil is by the use of green 

 crops. Sir Thomas A. Knight, in his experiments 

 upon manures, found that seeds germinated and 

 grew more rapidly which had been manured with 

 green vegetable substances ; and he argues from this 

 that it was because the plant found there the sub- 

 stances suited to its nutrition in a state of elabora- 

 tion nearer to that in which they existed in itself; 

 ■ and that it was upon the same principle that car- 

 niverous animals were nourished by the flesh of 

 other animals more than by the materials which 

 constituted the food of their prey. 



Dr. Anthony Todd Thompson, in a review of the 

 same in the Gardeners' Magazine, says that it is a 

 question whether the sap of plants drawing their 

 nourishment from vegetable matter is in any higher 

 state of elaboration than those feeding upon de- 

 cayed manures. But he finds the advantage of the 

 use of the green manure, as in Mr. Knight's experi- 

 ments, to result from the difference in the degree 

 of heat. Green vegetable matter would, of course, 

 ferment rapidly, and heat would be the consequence; 

 so that the ground about such manures would be 

 affected by it, the germination of seeds and the 

 growth of plants would be hastened and increased. 



