50 APPARENTLY DIFFERENT EFFECTS 



ments might possibly have been obtained. So that all we as yet 

 know is, that different portions of a field, apparently uniform 

 in quality, may yield returns in corn, roots, and hay, which 

 differ much from each other. We have as yet no experiments 

 from which we can deduce the limits of such differences in 

 any soils. 



Again, when the same manure is added in equal quantities 

 to different portions of the same field, we have upon record 

 differences even greater than those observed upon un-manured 

 land. Thus 



1. In the same field of Mr Dockar of Findon, mentioned 

 above, and in the same season, two-eighths of an acre, dressed 

 each with 20 bushels of bone-dust per acre, gave at the 

 rate of 



First portion, . . 11 tons 9 cwt. 

 Second portion, . . 8 ... 14 ... 



Difference, ... 2 tons 15 cwt., or ^th of the whole. 



How is such a difference to be explained? Is it all due 

 to -previously existing differences in the quality of the soil? 

 or did the bones act differently on the two parts of the 

 field? 



We have already seen that, without manure, two portions of 

 this field differed in produce by If tons. But here, when the 

 bones were added, the difference between two other portions 

 became 2f tons. Was the previously existing natural difference 

 really greater between the two portions of the field to which 

 the bones were applied ? or was the natural difference exalted 

 in some way, more brought out by the action of the bones ? 

 or was there some cause in operation such as a greater degree 

 of moisture in one of the portions of land which caused the 

 bones actually to produce a greater effect on the one than on 

 the other ? The last supposition is by no means an unlikely 

 one ; but we have no data for determining whether any such 

 cause really existed, or, if it did, how much of the observed 

 difference of 2f tons was owing to this cause, and how much 

 to original dissimilarities in the soil. 



2. From four plots of red wheat, dressed two and two with 



