|| duals of some other species. 
| Excretion of PLANTS. 
ROTATION 
OF CROPS. 87 
from a given extent of surface. But what is the | of land which varied from 120 to 500 square 
amount of residue or refuse which is returned to 
the soil by such and such a crop? What, in a 
word, is the value of this residuary matter con- 
sidered as manure? ‘This is a point upon which 
only the most vague and indefinite ideas are 
generally entertained ; and it was with the pur- 
pose of substituting positive facts for mere 
guesses that J determined on weighing and an- 
alysing the vegetable residue of the several crops 
that enter as elements into our more usual rota- 
tions. My experiments were made upon breadths 
a 3 
D ue 
4 HO 
oo |SOH : 
Natureof |S 9S3}]onqn| Nature of the residues 
the.crop. [BRSISR Ss buried in the soil. 
Oo 8 horny sy 
fa] ons 
4 SS 
~~ 
lbs. | lbs 
Potatoes . | 11367] 2739 | Potato teps - - 
Beetroots 13678] 1668 | Beetroot leaves - - 
Wheat . 2150) 1837 | Stubble S68) 
Clover-hay 2292) 1810 | Roots dried in the sun 
Oats ; 1862) 1474 | Stubble - - - - 
Total , 31349} 9527 
Manure em- 
ployed . 
A 
It, therefore, appears that the refuse or residue 
of the several crops of a rotation represent both 
in quantity and in nature somewhat less than 
one-half of the manure originally put into the 
ground; I say somewhat less, because it must be 
remembered that in the sum of these residuary 
| matters, the beetroot leaves and potato tops must 
not be allowed to stand together, the one crop 
naturally excluding the other, or at all events 
the two hoed or drill crops not entering in this 
| proportion into the same rotation. The large 
quantity of organic matter restored to the soil 
| by several of the crops in the series, consequently 
explains how the rotation may be closed without 
| its being found indispensable to supply any ad- 
ditional manure in its course.” Plants also dif- 
fer widely from one another in the kind and 
amount of excrementitious matter which they 
| deposit in the soil; and, fer the most part, each 
species excretes substances which are more or 
less injurious to the growth of other individuals 
of its own species or genus, and at the same time 
more or less beneficial to the growth of indivi- 
See the article 
The same species, like- 
| wise, according to the manner in which a crop 
| of it is treated or disposed of, may differ very 
widely from itself as to beth the kind and the 
amount of the manurial matter which it depo- 
sits. Many a crop which naturally exercises a 
very exhausting action, may be so treated as to 
return to the soil everything which it abstracted, 
or even to impart to it much additional fertiliz- 
ing matter, or even to prove the occasion of de- 
positing upon it a comparatively vast amount of 
yards in extent. The clover roots and stubble 
were taken up with the spade, and before being 
dried, were freed from adhering earth by wash- 
ing. The beet-leaves and potato-tops were dried 
at once in the oven; and it was from each the 
general mass reduced to powder that samples 
were taken for ultimate analysis, before proceed- 
ing to which, they were carefully dried in vacuo 
at 230° F. In the following table is a summary of 
the results,together with the quantity and the com- 
position of the manure expended in the rotation. 
oq 3S \Elementary matter of the residues, 
| o 2 1 neo ss : : i 
Soo ES S|) 3 5 2 | Sag 
(Bre Sey ie a TES Te eles 
Se ANE Soca vali ae 
Ibs. | Ibs. | Ibs. | Ibs. | lbs. | Ibs. |. lbs 
2632 630 282 32 189 14 112 
- | 9599 | 1070 | 410) 55 330 | 48 236 
1283 | 950 | 460] 50 369 4 67 
1833 | 1418 | 615 | 75 523 | 26 178 
836 | 596 | 299 | 32 232 2 30 
16182 | 4664 | 2066 | 244 |} 1643 | 94 617 
9314 | 3305 | 391 | 2403 | 186 2995 
| 
as green manure, and all which are allowed to 
decay entirely where they grow, and especially 
all which are fed off where they stand by sheep 
or other live stock, are of this class. See the 
articles Green Manures, Fattow, and Fox. 
Some of the ordinary crops of the farm, too, are 
mightily controlled in their power of either ex- 
hausting the soil or manuring it by the stage of 
growth at which they are cut down, and the 
degree in which their reaped produce is eventu- 
ally restored or not restored to the ground. 
“ When a herbaceous plant,” remarks Professor 
Low, “is suffered to mature its seeds, and when 
any part of these seeds is carried off the farm, 
the plant affords, when consumed by animals, a 
smaller return of manure to the farm than if the 
same plant had been cut down before it had ma- 
tured its seeds, and been in that state consumed 
by animals. Thus it is with the turnip. This 
plant is with us sown before midsummer. In 
the first season, it forms a napiform root, and 
puts forth a large system of leaves. arly in the 
following season, it puts forth a long stem, which 
bears flowers, and the seeds are generally matured 
about midsummer, If this plant is removed in 
the first stage of its growth, that is, after it has 
put forth its large leaves and formed its bulb, 
and is then consumed by animals, if returns 
a great quantity of manure; but if it remains 
until the second stage of its growth, then the 
consumption of its stem and leaves returns scarce 
any manure. The juices of the root have appa- 
rently been exhausted in affording nutrition to 
the flower-stem, the flowers, and the seeds. It 
is beyond a question, that, in order to bring a 
very enriching manure. All crops ploughed in j plant to its entire maturity, by the perfecting of 
NN eee 
