VARYING QUALITY OF FARM- YARD MANURE. 55 



Gross weight. Bulbs, topped and tailed. 



First portion, . 10 tons 11 cwt. 8 tons 18 cwt. per imp. acre. 

 Second portion, 8 ... 2 ... 6 ... 16 ... 



Difference, . 2 ... 9 ... 2 ... 2 ... 



Of course we cannot say how much of this difference may have 

 been owing to the soil, and we can only infer that the manure 

 may have, in part at least, been the cause of it. 



2. In an experiment of Mr Murray's, made at Slap, I find 

 a nearer approximation in the crop on two portions manured 

 alike with 20 tons of farm-yard manure the one yielding 13 

 tons 10 cwt., and the other 14 tons 7 cwt. gross weight, and 11 

 tons 14 cwt., and 12 tons 6 cwt. respectively of bulbs. The 

 difference here in the gross weight is only 17 cwt., and in the 

 bulbs only 12 cwt., or about 5 per cent on the whole crop. 



I find on record very few duplicate experiments with farm- 

 yard manure alone, but there are several in which it was applied 

 along with other substances, which, being of definite composi- 

 tion, may be supposed to be of definite action. Thus 



3. On the same experimental turnip-field of Mr Murray, two 

 portions (one-eighth of an acre each) were manured alike at the 

 rate of 10 tons of farm-yard manure, and 10 bushels of bones, 

 decomposed by sulphuric acid, with the following results : 



Gross weight. Weight of bulbs. 



First portion, . 18 tons 7 cwt. 15 tons 17 cwt. 



Second portion, . 15 ... 8 ... 13 ... 5 ... 



Difference, . . 2 ... 19 ... 2 ... 12 ... 



In two other experiments on the same field, made with the dis- 

 solved bones alone, the separate pieces of land gave precisely 

 the same return both of tops and bulbs, (10 tons 18 cwt. gross.) 

 It is reasonable, therefore, to suppose that, when applied along 

 with farm-yard manure, the fertilising action of the dissolved 

 bones was also the same in both portions, and that the large 

 difference in the crops was due mainly to unobserved differences 

 in the quality of the farm-yard manure applied to them. 



4. But a more striking difference of this kind is recorded 

 among experiments made on the farm of Kerrytonlia, in the 



