EXPERIMENTS AT CIRENCESTER 89 



there is a notable increase in the crop, the increase ob- 

 tained is however not as great as that given at Rothamsted 

 by the combined use of superphosphate and alkalies. 



When we turn to the group of plots receiving ammonia 

 salts we are met by the same fact which appeared in the 

 barley experiments, namely, the comparatively small return 

 obtained from the use of cinereal manures on the soil at 

 Cirencester. The entire omission of alkali salts on plot 4 pro- 

 duces no diminution in the hay crop. The omission of super- 

 phosphate also produces very little effect. The entire omission 

 of all cinereal manure reduces the crop by 5 cwts. At 

 Rothamsted this omission produced an annual loss of 23-1 

 cwts. in the first ten years of the experiment. 



The produce of hay by 12 tons of farmyard manure is on 

 an average of nine years almost identical with that given by 

 2 cwts. of sulphate of ammonia and cinereals on plot 8. 



Very little information is furnished by the Cirencester 

 reports as to the botanical character of the herbage on the 

 various plots. 



The return for the ammonia applied is 4-9 cwts. of hay for 

 i cwt. of sulphate of ammonia when this salt is used alone, 

 and 6-3 cwts. of hay when the salt is used with superphosphate. 

 As in these experiments the effect of alkali salts is very small, 

 we may take the last named figure as representing the best 

 return from the ammonia salts in these experiments. 



3. Experiments at Pumpherston. Trials of the effects 

 of very various manures on the mixed herbage of land just laid 

 down to grass have been conducted by Dr. A. P. Aitken at 

 Pumpherston, the results are published in the Transactions 

 of the Highland and Agricultural Society. The land has 

 been divided into plots, receiving pretty continuously the 

 same manures since 1878. P'rom 1878 to 1887 the land was 

 cropped as a rotation. In 1887 grass and clover seeds were 

 sown with the barley, and the land has since remained in 

 grass. The mixture of seeds was one suitable for the forma- 

 tion of permanent grass. 



From 1878 to 1885 the manures applied were at the rates 

 of 1 60 Ibs. of phosphoric acid, 120 Ibs. of potash, and So Ibs. 



