326 



FARMERS' REGISTER. 



No. 6 



determine whetfier these crops eiirpa?s those of 

 common culture; and it remains to ol)serve, that all 

 the early varieiies were irench planted, and amon<ij 

 those, I includethe first variety of kichiey, at the 

 head of the list. The keepers (2-5) were planied 

 row by row, durinir the process oi'diffiring and the 

 rows (feneraliy lour leet asunder. Thus the irround, 

 which had previously been under 6rocco/(", wasdiji'- 

 ged lo the extent of five (eet ; then a line being 

 siretchcd, a <hill-trench was chopped down with the 

 spade, drawing the loosened soil forward six inches 

 deep. The sets were herein deposited, five or six 

 inches apart, and were covered with earth made 

 very fine and Iii>ht ; then another space was digged, 

 and a second trench struck out and planted. I have, 

 in the present season, made a further improvement, 

 by sprinkling an inch-deep layer ol light hot-bed 

 manure, over the eurlace of the ground which 

 covers the tubers ; thuseach row is clearly marked, 

 the soil protected, and enriched, to the width of a 

 foot, without bringing manure into contact with 

 the potatoes. After a time, when the haulm has 

 become six inches liigh, the intervening spaces 

 are fork-digired, or the soil otherwise, by hoe or 

 spade, rendered light ; the little manure which 

 remains is thus intermixed with the surface, and 

 about two inches of earth is drawn over it, and 

 against the stems on each side; this is all the earth- 

 ing I allow. The soil remains loose and free at 

 top, over a more solid stratum beneath. This is 

 the actual condition the plots are in at the moment 

 of writing (July 29). 



It has been conjectured by many, who have 

 accordingly adopted the practice, that potatoes 

 may be planted year after year in the same land. 

 I have never risked the trial to an extent sufficient 

 to decide the question, and, indeed, the difference 

 of soil would ai once throw an obstacle in the way, 

 which could not be surmounted ; but as far as 1 

 have seen, a loam constituted as mine is, does not 

 appear to bring two successive crops of the same 

 potato to a corresponding degree of perfection. 

 It is not to be doubted, that all plants convey into 

 the soil matters either gaseous, fluid, or solid — for 

 the odor diffused will prove the fact to a demon- 

 stration ; therefore, without dwelling upon the 

 theory of radical, fecal exudation, or clainiing tlie 

 admission that, by analogy, whatever a plant 

 throws off from its system cannot become salubri- 

 ous food for another of its own species, it certainly 

 appears reasonable to vary the crops according to 

 the order of rotation, either in the field or garden. 

 I have acted by this principle, and, whenever it 

 has been in my power, have planted one or other 

 of the cabbage family after potatoes. 



But in reasoning by the rules of rotation, we 

 must not be led away from particular liic's. The 

 tubers of the potato- plant do not appear to derive 

 support from the soil, they being appended to pro- 

 cesses which are conduits of supply downward or 

 laterally from the leaves and stem ; the sap-fibres 

 which convey the fluids upward are wholly inde- 

 pendent of these processes. Just in proportion to 

 the amplitude of foliage, duly exposed to the sun 

 and air, is the bulk of the crop ; hence, although 

 manure, or humus, becomes decomposed by the 

 action of the proper roots, and is by them convey- 

 ed in the form of raw sap to the herbaije, the 

 ground does not become impoverished by the po- 

 tatoes themselves, however numerous they may 

 be, they being organic bodies (propagines),ov sya- 



tem onife — a congeries of new plants imbedded in 

 a pulpy and amylaceous mass, which has no con- 

 nection whatever with the soil. Hence, also, as the 

 potato is thus viewed as a product of the leaves, it 

 becomes the recipient of the exudation, which it 

 thus prevents from coiilaminaiing the ground to 

 any consid(.Table exient; and thus, upon the 

 theory of fecal exudation, the potato may be plant- 

 ed year after year on the same spot of ground, 

 with comparative safety, but by no means advan- 

 tageously. 



Little remains to be said. The crops I have 

 produced, and llieir excellent quality, prove, that 

 the rows may stand widely apart, and thus llirnish 

 ample space lor the horizontal expansion of the 

 radical processes, without causing any diminution 

 of the yield ; lor what is lost in space one way, is 

 made up by the proximity of the sets in the rows. 



The loam (as a staple, naturally) is composed 

 chiefly of a gritty gravel, containing a little chalk, 

 more iron, and a moderate portion of alumina — ■ 

 the matter of pure clay ; its vice, is the condition 

 of the sand, or siliceous constituent, which renders 

 it bindincT, under the influence of a hot sun, after 

 rain. A perfect loam requires the silex to be in a 

 stale of minute division. If this fine silex abound, 

 even to the exient of five-sixths of the whole bulk, 

 leaving the remaining sixth to he composed of 

 alumina, sub-oxide of iron, of a light ochre tint, 

 and chalk ^carbonate of lime,} the loam will be rich, 

 unctuous, and of high quality ; but if a consider- 

 able portion ol' the silex is coarse (the detritus of 

 gravel), the texture of the loam beconues vitiated, 

 and it sets like a brick. Those loams, wherein the 

 iron exists in the Ibrm of a per-oxide, assume a 

 purple, or red tint ; they are abundant in Somer- 

 setshire, and are the staple of permanent fertility. 



Agriculture, or the science of cropping and ruta- 

 tion, will never be duly understood, till the consti- 

 tution ofall loams, and their power of decomposing 

 manure under the stimulus of the vital, vegetable 

 principle be accurately determined by experiment.* 



ESSAY ON VEGETABLE PHYSIOLOGY. 



[Continued from page 271.] 



Chap. XII. 



NATURE OF THEORIES. THEORETICAI. ORI- 

 GIN OF THE FLOWER. BIETHOn OF REN- 

 DERING BARREN TREES FRUITFUL,. 



For tlie Farmers' Register. 



In treating of natural phenomena, we very fre- 

 quently suppose a cause from which they may 

 have arisen, and, for the time, considering this as 

 the true cause, proceed to point out the manner in 

 which they must have been produced. Where the 

 phenomena result so naturally from the supposed 

 cause, as to render it highly probable that it is in- 



* When Mr. Towers was explainin;^ the character 

 of the JEgrostis scgefum, in p. 89, of this volume, we 

 expressed a doubt of the insect described being an 

 iEgrostis. It is but justice to Mr. Toweis to take this 

 opportunity of stating, that from tlie facts which he has 

 since furnished, regarding the character of the insect 

 he described, we are quite satisfied that it is the 

 ^grostis segeium, and no other. — Editor. 



