i9°9r] Summary of Agricultural Experiments. 405 



The planting of large tubers results in a very much greater proportion 

 of seed potatoes than if ordinary seed is used. In two trials which were 

 undertaken to ascertain the difference, a yield of 2 tons 9 cwts., and 

 3 tons 7 cwts. of seed potatoes, were obtained when large tubers were 

 planted, as against 16 cwts. and 17 cwts. respectively when seed was 

 planted. The variation in the total crop was not great. It will be 

 seen, therefore, that when growing for seed, the use of large tubers 

 is profitable, but if practised when growing for market, it would result 

 in a distinct loss. The weight of large tubers planted was 31^ cwts. 

 per acre, against 15 and 17^ cwts. of seed. 



The results of some experiments to test the effect of change of seed 

 are recorded, and also some comparing Irish with Scotch seed. The 

 Irish seed gave better results than the Scotch seed in each case. 



Miscellaneous Manurial Experiments. 



Rotation Experiment (Journal Royal Agricultural Society, Vol. 69, 

 1908). — The object of this experiment, which is still being carried on, 

 is to see what increase of crops during the rotation is obtainable from 

 the use of decorticated cotton cake as compared with maize meal, or 

 from either as compared with no cake or corn ; in other words, to 

 ascertain what is the unexhausted manurial value of these foods, accord- 

 ing as they may be, in the one case, fed direct on the land by sheep, or, 

 in the other case, used by bullocks in feeding boxes for the production 

 of farmyard manure. The results are given for 1908. 



Rotation Experiment (Aberdeen College of Agriculture, Bulletin 

 No. 10). — In view of the importance of determining the residual value 

 of manures, a number of rotation experiments have been arranged in 

 the northern counties, and the figures relating to one which has been 

 in operation for three years are given in this report. This experiment 

 is designed to ascertain the residual value of the ordinary phosphatic 

 manures. There are nine plots, each \ acre in extent, and the first 

 four plots received a standard dressing of 20 lb. nitrogen, 100 lb. phos- 

 phoric acid, and 40 lb. potash per acre, but on each plot the phosphoric 

 acid is derived from a different source. Plot 5 is unmanured, and plots 

 6-9 are dunged at the rate of 10 tons per acre, and receive just half 

 the quantities of fertilisers applied to the first four plots. The last four 

 plots are, therefore, duplicates of the first four, with the difference that 

 half the artificial manure is omitted and replaced by the dung. The 

 phosphates used were superphosphate, basic slag, bone meal, and ground 

 Florida phosphate. 



The rotation during the three years has been turnips, barley, hay, and^ 

 by deducting the cost of the manures applied, the results may be com- 

 pared with those obtained from the unmanured plot. Taking the first 

 four plots, which received no dung, superphosphate gave a profit of 

 20s. per acre, basic slag 175. 3d., and ground Florida phosphate, 55. gd. 

 The application of bone meal has up to now resulted in a loss of 275. 3d. 

 per acre. This is due to the fact that the plot receiving bone meal pro- 

 I duced a much poorer crop of barley than any of the other plots, and 



I less also than the unmanured plot. 

 When the manures were applied with dung, they have all left a profit, 

 by far the largest being from the Florida phosphate. The plot receiving 



