SCIENCE OF GARDENING. 



127 



{oxygen a7id charcoal or carbon,) and of am- 

 monia, {hydrogen and nitrogen.) 



We make no allusion to manure in its 

 limited sense, as applied agriculturally, but 

 look at it broadly in its most simple, as well 

 as most complicated form ; and therefore, 

 to make a commencement, we refer to that 

 most feeble of all substances employed by 

 the gardener, usually styled -peat, and for- 

 merly called bog earth. This black-greyish 

 or brown soil consists chiefly of white sili- 

 ceous sand, mixed with varying portions of 

 fern, bog moss, (sphagnum,) heath leaves, 

 rushes, or similar matter, in a condition of 

 progressive decay. It is seldom used fresh, 

 but usually laid up in heaps to mellow, for 

 woe be to him who shall touch it in its 

 pristine state. Buried in the darkness of 

 ages, swamped with water, and of a buty- 

 raceous compact texture, it is incapable of 

 affording support to any plant but the mise- 

 rable herbage upon its surface. Yet this 

 crude earth is a mine of manure, and by the 

 operation of air, light, and atmospheric elec- 

 tricity, it is meliorated, and becomes qua- 

 lified to support all the hair-rooted tribes 

 which are now so ornamental in our best 

 gardens. To one ignorant of chemical 

 principles, and who shall use it fresh, the 

 consequences are inevitable; " it burns eve- 

 ry root it touches," — the plant dies* 



This " burning," which is a Avord in com- 

 mon use, is false in application, though its 

 effects are apparent. Plant an Azalea in 

 fresh peat, and in a few days, the points, 

 then half the leaA'es, become brown, the 

 shrub ceases to grow, the leaves fall, and 

 it perishes. But keep this same soil during 

 two seasons exposed to the weather, turning 

 it occasionally, and the same species which 

 would perish in it while fresh, now grow, 

 and thrive luxuriantly. To what then is 

 this "burning" attributable? To the ef- 

 fects of gaseous developments, produced by 



progressive decomposition of the redundant 

 vegetable matter. In farm-yard dung, am- 

 vioniacal gas is copiously extricated, but in 

 peat or heath soil, some neutral salt of iron 

 exists, (the sulphate probably,) which is 

 gradually decomposed, loses its acid, and 

 becomes an innocuous oxide. 

 [ But this is a digression, though one 

 which involves many curious phenomena — 

 it is our object to show, that simple as is 

 this heath soil, an Azalea, a Rhododendron, 

 an Erica, or Andromeda, may grow in a pot 

 of it for years, and never exhaust it of any 

 portion of its " humus " or black vegetable 

 matter. If any discemable alteration takes 

 place, the tint becomes darker, as if finely 

 powdered charcoal had been added to it. 

 True, the plant will require fresh aliment 

 and more space, but not because the soil is 

 exhausted. The vegetable adds to the soil, 

 or rather ejects into it foecal and excremen- 

 titious substances, which consequently can- 

 not be taken up a second time with impu- 

 nity into its organic tissue. 



It is every day becoming more and more 

 apparent, that soils are changed by cropping, 



hut never exhausted. The earths proper 



alumine, sand, lime and oxide of iron 



may be taken up, to a very small extent, in 

 a state of solution in water, but they retain 

 their qualities in the mass, the soluble salts 

 of the soil — potassa, soda, and their sul- 

 phates, nitrates and muriates, or ammonia 

 and its salts — these are the substances 

 which vanish, and must be renewed by ma- 

 nures. We, therefore, urge upon our hor- 

 ticultural friends, to examine strictly all the 

 earths they employ before they plant in 

 them, and at every shifting. By thus in- 

 vestigating, a person may soon satisfy him- 

 self, that a soil becomes replete with speci- 

 fic odors, that its texture is changed, and its 

 nutrimental power deteriorated, as respects 

 the individzial plant, while it becomes ex- 



