348 Mineral Manures, and the Value of 



We shall not repeat the valuable tabular results given, the 

 foundation of a vast mass of agricultural information, but 

 simply go through the gross results of the application, as 

 regards weight of crop, with these four experiments. 



Mr. Cholmeley's turnips, grown on a loamy clay, had the 

 heaviest crop on No. 3, the dung coprolite and guano beating 

 the farm-yard manure by some 5% tons per acre. 



Mr. Johnson's experiments were tried with various ma- 

 nures, singly ; and his Peruvian guano gave the greatest 

 weight of the class of substances tried, but 10 cubic yards 

 of farm-yard manure had previously been applied to the 

 whole land. 



Mr. Maulevere's heaviest weight, when the manures were 

 also applied singly, was with the 12 tons of dung, but only 

 14 cwt. more than the dressing with 2 cwt. of coprolites. 

 This soil was a light clay. 



Mr. Newham's, on a limestone soil, were the heaviest with 

 No. 3, — the same as Mr. Cholmeley's, — and were 16 cwt. 

 heavier than an application of dung alone. 



Mr. Outhwaite's, on a hungry gravel, were the heaviest, 

 with 9| tons of dung and 2 cwt. of guano, for all the land 

 had been dunged at this rate, and exceeded 14| tons of dung 

 by 2 tons 9 cwt. per acre. 



Mr. Scott's were the heaviest on No. 4, — the guano and 

 coprolites, and 1 ton 7 cwt. more than 20 tons of dung, — 

 his soil was a strong loam. 



Mr. Wailes's were the heaviest, with 4 cwt. of guano and 

 4 cwt. of coprolites, showing an increase over 20 tons of 

 dung of 2 tons 9 cwt. per acre ; the soil is a useful loam. 



The first fact which strikes the observer is that, as a gen- 

 eral rule, there is not only an addition to the crop by the 

 addition of these artificial manures, but there is, in some 

 cases, more absolute crop produced by them than by farm- 

 yard manure alone. 



Now, to bring this to the test of figures, the coprolites at 

 £5 per ton, and the guano at £10 per ton, will be at the rate 

 of 2 cwt. of each, £1 10s. per acre. Now, assuming this 

 to be equal to 20 tons of dung per acre, we should require to 



