INFLUENCE OF THE SEASONS. 69 



Dale's hybrid, . . .20 tons 6 cwt. 



Gibb's red-topped yellow, . . 13 tons 13 cwt. 



Difference, . . 6 tons 13 cwt. 



An experiment, therefore, which should simply describe the 

 effect of a certain application on a yellow turnip, without speci- 

 fying the sub-variety, might be contradicted by the result of 

 another in which a different sub-variety had been experimented 

 upon, and upon which the result had been very different. Even 

 seed of the same sub-variety, grown in different places, often 

 gives different weights of crop. 



In regard to wheat, oats, and barley, I might give similar 

 illustrations of the effect of variety or change of seed, but with 

 this almost every practical man is familiar. 



It is altogether uncertain, as yet, how far this curious influ- 

 ence of variety, of sub-variety, and even of mere change of 

 seed, will ever be brought within the dominion of chemistry, 

 or admit of being either explained or controlled. Its exist- 

 ence, however, is of much practical importance to the farmer, 

 and ought not to be lightly valued by the scientific experi- 

 menter. 



7. Influence of the seasons on the results of field 

 experiments. 



In turnip husbandry, the influence of a seasonable rain, after 

 the seed is sown, illustrates the kind of advantage which one 

 application, upon which an early rain falls, may have over 

 another which is succeeded by continued drought. Hence the 

 recommendation to apply artificial manures immediately before 

 or after rain, or while moist weather prevails. All field experi- 

 ments which are to be tested by weight and measure are 

 especially open to this cause of diversity in their results. In 

 the same season the application in more or less propitious wea- 

 ther and in different seasons the occurrence of more or less 

 rain, or colder winds, or hotter days will materially modify 

 the results obtained with the same substances upon similar soils 

 and crops. 



