191 1.] Experiments in Potato Growing. 



893 



errors due to variation in the soil, and no outside row was 

 included in the area to be weighed. 



The results of these duplicate plots in the great majority 

 of cases did not vary by more than one ton per acre. The 

 regularity of the yield is shown by the following figures. 



Variations of less than 10 cwt. per acre ... ... ... ... 159 



between 11 cwt. and 20 cwt. , per acre 87 



>> >> 21 ,, 30 ,, 39 



» „ 31 „ 40 „ 19 



» >> 4 1 >> 5° ,> 11 



above 50 cwt. ... ... ... ... 4 



Total number of pairs of plots ... ... ... 319 



The same number of sets was planted on each plot, usually 

 49 per row, at uniform distances of 14 in. apart. Approxi- 

 mately the same weight of sets was planted on each plot. 

 It would have been desirable to have planted the same weight 

 on each, but so long as the sets are of moderate size, number 

 is much more important than weight. In many of the experi- 

 ments, however, the weight per lot was equal, being 42 lb. 

 on a T Vth-acre plot; or 15 cwt. per acre. It was found 

 impossible to secure equality of both number and weight 

 when dealing with purchased tubers, so number was selected 

 in preference to weight, as in the earlier years of these trials 

 it had been found that a difference of 2-3 cwt. per acre in 

 seed rate made no material difference to the total weight of 

 crop. This question of size of sets will be more fully dis- 

 cussed later. 



It was the usual custom to plant whole sets, but occa- 

 sionally when using purchased tubers, or when only small 

 quantities of home-grown ones were available, it was neces- 

 sary to cut the sets. The effect of this treatment will also be 

 discussed later. 



Of all the points in connection with the potato crop, that 

 which requires the most careful attention of the grower is the 

 source from which his seed is obtained. This fact has been 

 impressed upon us more emphatically each year, and some 

 of the earlier conclusions are invalid because a full knowledge 

 was lacking of the conditions under which the potatoes sup- 

 plied to us were grown. 



The storing of seed for experimental work needs careful 

 attention to see that each series of plots has identically the 

 same treatment prior to planting, and the better way appears 



