348 



(Letters on Modern AgricuUure, p. 41), an average crop of potatoes 

 removes from each acre about 16'3 Ibs. of mineral matter; and one 

 of beet about 458 Ibs. (leaves included). 



"With respect to climate, cotton needs a high summer temperature ; 

 although not properly a tropical plant, it produces fibre in diminished 

 quantity, though of improved quality, when removed from a southern 

 locality to one further north ; it never seems to be directly injured 

 by the most intense midday heat ; when other crops, including even 

 Indian corn, are drooping under a blazing sun, the large succulent- 

 looking leaves of a cotton-field will but seem to enjoy the congenial 

 temperature. As is said by the writer of a pamphlet published by 

 the Cotton Supply Association " cotton is decidedly a sun-plant." 



The proper supply of moisture is a point of at least equal import- 

 ance with temperature, and here appears undoubtedly to lie the main 

 difficulty hitherto experienced in attempts to extend the culture of 

 cotton into new regions. Published statements differ greatly as to 

 the effect of moisture or dryness upon the plant, some writers saying 

 that a wet season is ruinous to cotton and that drainage is of the first 

 importance ; while others, especially many of those treating of cul- 

 tivation in India, insist that irrigation is more necessary than anything 

 else. Dr. Royle* well says, "such terms as moisture and dryness 

 are so entirely comparative, that in one country we hear the cotton 

 plant described as one requiring moisture, and in another we find it 

 stated that no plant requires so little ; the fact being, that the plant 

 can hear both great heat and considerable want of water, provided it 

 is growing in a not over-dry atmosphere." 



The last sentence states an important part of the truth, but, I 

 think, not the whole ; it draws a distinction between two forms in 

 which moisture may be supplied to the growing plant, whereas it 

 would seem that/bwr should be separately noticed. 



1. The atmosphere may contain a greater or less amount of water 

 in the state of vapour, up to the point of so-called saturation. 



2. The atmosphere may be supersaturated, or in other words, 

 precipitation of liquid water, as rain, &c., may take place from it. 



3. The soil may contain a greater or less amount of water inti- 

 mately united with it, whether by adhesion or chemical combination 



* Dr. J. Forbes Royle ' On the Culture and Commerce of Cotton in India and 

 elsewhere,' p. 223. 



