DR. DAUBENY ON THE ROTATION OF CROPS, ETC. 



189 



It is worth remarking, that the average of the shifting crops of potatoes corre- 

 sponded very nearly to the amount obtained in the year 1844, from a bed of similar 

 size, in a portion of the garden contiguous to that on which my experiments had been 

 carried on, and which had been recently manured, the produce in this instance being 

 96*0 lbs., whilst the average of nine years in the other case was 89*1 lbs., and 

 moreover that the produce of the last year, in which the crop succeeded one of barley, 

 was not less than 98 lbs., thus apparently showing, that after so long a period of 

 cropping, there was still a sufficient supply in the soil of those ingredients which were 

 requisite for the due development of the plant. 



An examination of samples of potatoes from the crop of 1844 proved, that the 

 shifting crop contained more starch, and more of the woody fibre and other organic 

 matters which belong to this vegetable, than either of the permanent ones ; and that 

 of the latter, the one grown in soil which had borne potatoes only five years, ap- 

 proached in these respects more nearly to the shifting, than that taken from the soil 

 which had been cropped during ten years. The proportion of water in the two 

 cases was not very different, but with respect to the inorganic matters, it was found 

 that the remark held good. 



Here the shifting crop yielded in a given amount of tubers the least, and the per- 

 manent crop the largest quantity of ash, as if the. deficiency of organic matter had 

 been made up by an increased quantity of that which was derived from inorganic 

 sources. The nature of this latter portion will be stated when I proceed to detail 

 the analyses performed by Mr. Way. 



On examining a specimen of a good mealy description of potatoe taken from a 

 garden in the neighbourhood of Oxford, the soil of which was similar to that of the 

 experimental garden, I found the proportion of starch much the same as in the shift- 

 ing crop, but the quantity of water greater. '■ 



The following is a tabular view of the results : — 



Good mealy kind of potatoe from a garden near Oxford 



Shifting crop in experimental garden 



Permanent crop of five years' standing 



Permanent crop of nine years' standing 



Starch. 



per cent. 



13-00 



13-67 



10-54 



9-11 



Fibrous 

 matter. 



5-90 



9-76 



11-32 



9-76 



Other solid 

 matters. 



5-6 



5-7 



4-5 



Water. 



75-5 

 71'9 



73-7 



72-4 



2. Hordeum sativum. 

 The next crop I shall notice is Barley, in which it will be perceived that, allowing 

 for differences of seasons, the produce obtained during ten successive years was tole- 

 rably uniform, there being however a considerable balance in favour of the shifting 

 over the permanent crop. 



2 c 2 



