86 



The Solanum Commersoni. 



[may, 



The Board's leaflet goes on to state that it would be art 

 improvement, though involving a little more trouble and 

 expense, to use only \ cwt. of nitrate of soda and \ cwt. sulphate 

 of ammonia, and to add \ cwt. of fish guano, and \ cwt. of 

 Peruvian guano. Five to 6 cwt. per acre of such a mixture may 

 be used with a moderate dose of dung. 



When potatoes are grown after a two or three years' lea 

 without farmyard manure, a mixture of \ cwt. nitrate of soda,, 

 i cwt. sulphate of ammonia, 2 cwts. dissolved bones, 3 cwts. 

 superphosphate, and 2 cwts. sulphate of potash per acre may 

 be employed . 



The slowness of action of basic slag renders this manure 

 unsuitable for use on potatoes. This is borne out by the 

 experiments above referred to, where the substitution of basic 

 slag for superphosphate gave a smaller yield by 17 cwt. 



Reference was made in an earlier number of this 



Journal* to the introduction into France of the Solanum 



™, c . _ Commersoni, a tuber of the potato 



The Solanum Com- ■ . . , y 



mersoniandthe family ' fr0m whlch a vanety dlstm " 

 « Blue Giant" Potato. gulshed aS " Violet " was obtained. 



This variety proved to have an excellent 

 flavour, similar to the ordinary potato, and its cultivation 

 promised to be of importance. Further investigation, however, 

 has given rise to doubts as to how far it can be distinguished 

 from the variety known as Blue Giant. In an article in the 

 Journal Agriculture Pratique, January 24th, 1907, M. Philippe 

 de Vilmorin reviews the opinions expressed by various experi- 

 menters, and points out that, owing to the well-known influence 

 which a change of soil or climate has upon the potato, it is neces- 

 sary, for the purpose of exact comparison, that tubers should 

 be grown under exactly similar conditions for two or three 

 seasons, as any newly imported tuber is likely, in the first 

 season, to be more vigorous and leafy, and to give a better yield 

 than a tuber of the same variety grown for some seasons in the 

 same soil. Trials conducted by M. de Vilmorin on these lines 



* Oct. 1904, p. 412. 



