NOTES AND ABSTRACTS. 



517 



Rhododendron primulinum,HemsL By W. B. Hemsley [Gard. 

 Chron. xlvii. (1910), p. 4 ; Jan. 1). — Consists of a description of this 

 beautiful species, which reaches a height of 1^ feet to 2 feet and pro- 

 duces its rotate, yellow flowers when only a few inches high. A new 

 species raised by Messrs. Veitch from seed collected by Mr. E. H. 

 Wilson in W. China.-— F. J. C. 



Rhubarb Flower (Le Jard., vol. xxiv. No. 554, p. 95; March 20, 

 1910). — The young flowering shoots of rhubarb are said to be quite as 

 good to eat as the cauliflower. They should be cooked like rhubarb, 

 and provide an excellent and tender vegetable. — F. A. W. 



Roses, Hybrid. Multiflora and Wichuraiana {Le Jard., 

 vol. xxiii., No. 543, p. 295; Oct. 5, 1909; with 9 figs, and one coloured 

 plate). — An interesting article on the various hybrids that come under 

 the above classes, with suggestions as to the many ways in which they 

 can be employed in landscape gardening. — F. A. W. 



Rotation of Crops. By W. M. Hays, Andrew Boss, A. D. 

 Wilson, and Harry Snyder (U.S.A. Exp. Stn. Minnesota, 16th Ann. 

 Report, pp. 283-358; with 13 figs. ; 1908). — A series of careful experi- 

 ments on 44 plots, to test the effect of rotation on average yield and 

 on the chemical and physical condition of the soil, have been carried 

 out for ten years at this station. It is shown that in five years the total 

 fertility removed by continuous wheat was 148 lb. nitrogen, 84'6 lb. 

 phosphoric acid, and 148 lb. potash. With rotation 115 lb. nitrogen, 

 141*5 lb. phosphoric acid, and 383'6 lb. potash were removed. Eota- 

 tion, with the use of farmyard manure, improves the condition of the 

 soil (chiefly by the effect of decomposition in producing acids which 

 render more mineral constituents soluble, and therefore available as 

 plant food). 



Vegetable matter may be added to the soil much more cheaply 

 than commercial fertilizers. Many New England farmers used these 

 last until their soil no longer paid for the use of fertilizers, and were 

 eventually forced to abandon their farms. 



The details of the 44 plot experiments are given in full, and con- 

 tain much that is of great interest to farmers and agriculturists. 

 The value of each crop during the years 1893-1904 is calculated in 

 dollars. The difference in the crops of Indian corn, when grown con- 

 tmuously (average 16 bushels) and when grown as a rotation crop 

 (48'2 bushels) is very marked. Very poor results were also found 

 when potatos, mangels, and peas were grown continuously on the 

 same land. When wheat was grown continuously there was a 

 gradual steady decrease in the yield. This was less marked when 

 6 lb. of Eed Clover was sown on the acre. The value of clover comes 

 out very clearly in these tables, not only on account of its direct 

 nitrogen-forming effect, but also by its preventing the development 

 of weeds. Flax was not found to be a hard crop on the soil. 



