EXPERIMENTS OX THE CULTURE OF TUEXIPS. 255 



Phosphates, both soluble and insoluble, have given a much 

 larger increase this season than in 1879 ; indeed, the great 

 increase of crop over that year appears to be principally due to 

 phosphates. The results of potash are 12 cwts. per acre behind 

 those of 1879. The results of the application of nitrogen are 

 not comparable, as the one year it was put on with phosphates 

 alone, and the next with phosphates and potash combined. 

 This year's weighing of the plots shows the unexpected result of 

 37 cwts. per acre in favour of ground phosphates. It is neces- 

 sary, however, to repeat, that the phosphates used were of the 

 highest class and capable of being ground to the finest state of 

 division, and they certainly were better ground than those I 

 used last year, being passed through a screen eighty holes to the 

 inch, and as fine as the best flour. 



The value of a manure depends on the rapidity and complete- 

 ness with which it is capable of being absorbed and assimilated 

 by the plant. The same manure may be ground to two states 

 of fineness, so that the one may expose double the amount of 

 surface to the action of solvents that the other does, and yet 

 both be considered finely ground. The result, therefore, would 

 be, that 'the more coarsely ground phosphates would require 

 double the time to be absorbed by the plant in comparison with 

 the other ; and hence to the fineness of subdivision I attri- 

 bute in a great degree the better comparative results given 

 this year by the ground phosphates as compared with those got 

 in 1879. On the Craichie station I had good practical proof of 

 the correctness of this theory of fine grinding. Mr Warden 

 manured the continuation of the drills at that station with a 

 well-balanced mixture, containing a fair proportion of potash, 

 nitrogen, and phosphates. The pliosphates were partially soluble, 

 but the larger proportion of them were insoluble. This manure 

 was in a very rough state of division as compared with the 

 manure used on the plots, and although as much potash, nitro- 

 gen, and phosphates were used as on the tri])le plots of tlie station, 

 the result in weiglit of crop was little better than the produce 

 of phospliates alone. The cause of this deficiency I ascribe 

 partly to the rough state of division, partly to the combinations 

 of the various constituents of the manure. At Auchindorie the 

 general crop was grown with artificial manure, and both manure 

 and results were similar to those at Craichie. . 



At Craichie the general croj) was grown with 14 tons farm- 

 yard and () cwts. mixed artificial manure per acre. The produce 

 of this api)lication weighed 2 tons per acre less than the tri}»le 

 plots of the insoluble phosphate sei'tion which IkhI no farmyard 

 manure. At the Sandy ford yi'llow turnip station, the trij)le 

 plots and the general crop grown with 111 tons farmyard and 

 7 cwt. of mixed artificial manure, gave about equal weights. 



