Experiments on the Potato- Crop. 553 



Our primary question is whether an increase in the size of 

 the set will produce an excess above the extra weight of the sets 

 planted ; such extra weight going to increase the strength of the 

 individual sets without increasing their number ? 



The unequivocal results in favour of large sets, obtained from 

 my experiments carried out in 1864, and recorded in the ' Gar- 

 dener's Chronicle,' as well as from those which form the subject 

 of this report, induce me to describe carefully the conditions 

 under which the experiments were conducted. 



Every precaution was taken to insure the most perfect uni- 

 formity in the conditions under which the various experiments 

 were made. The manure was separately weighed out, and 

 distributed on each 20 superficial feet of ground. The distance 

 — 2 feet — between the rows was the same throughout the trial 

 ground ; and to counteract the influence of any slight variations 

 in the character of the soil, the particular experiments that 

 would be brought into immediate comparison were placed as 

 nearly as possible in juxtaposition. External rows were rejected 

 for the experiments, and planted with part of the ordinary crop; 

 and every individual set was separately weighed and selected to 

 the specified size, and planted to measure, at precise distances. 



Notwithstanding these precautions, there was a want of cor- 

 respondence in many of the individual results, which I would 

 notice as a warning against depending on the evidence of single 

 experiments : for instance, in plots planted under precisely the 

 same conditions, and with no apparent difference in the appear- 

 ance of the crops, the produce varied to the extent of several tons 

 per acre. Similar inequalities, apparently unaccountable, will 

 be found in all agricultural crops, and in the conduct of experi- 

 ments every care should be taken that they are fully recognized 

 in the calculation of results. 



Under the head of " Accidental Variations of Result " at the 

 end of the report, I shall consider this subject more in detail, 

 and endeavour to show the extent to Avhich these adventitious 

 irregularities affect the general tenor of the experiments. 



It remains now to consider separately the various points to 

 which the experiments relate. 



It will be found that I have in no case relied on isolated 

 results, but drawn the conclusions from the general bearing of 

 the series. Throughout the report the term "Gross Crop" will 

 apply to the whole weight of potatoes produced per acre, and 

 " Net Crop " to the balance of produce after deducting the 

 weight of the sets from which it was grown. 



Firstly. The influence of the size of the set on the economic results 

 of the crop; or lohether any increase, and to what extent, is 



