88 MANURES. 



lime) or even sulphate (gypsum) may be a 

 useful manure for that vegetable — for lime 

 neutralizes acids which may be found in the 

 soil, many of which are injurious ; it decom- 

 poses and prepares various other substances, as 

 mucilage or gum which readily dissolves and 

 alters phosphate of lime, thus the hurtful exuda- 

 tions of roots partly possessing this mucilaginous 

 nature may perhaps thereby be rendered inno- 

 cuous or useful, &c. There is indeed perhaps 

 as much or more yet to be discovered on this 

 subject than what we actually know. 



Man sows and cultivates many acres of the 

 same plant together, hence arises the necessity 

 of manure and rotation. Nature mixes all her 

 plants in varied and beautiful profusion — 

 hence, no manure or rotation is necessary, the 

 exudations of the roots of one plant become 

 food for another, and the same plants remain 

 growing on the same spots for years, nay ages. 

 Yet when nature does, as in the case of forests, 

 produce the same tree to a large extent — the 

 American forests teach us that there rotation 

 also becomes necessary. It would be a curious 

 experiment to endeavor to ascertain whether 

 the exudations of parasitical plants were benefi- 

 cial or otherwise to the trees on which they are 

 said to feed. 



