78 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



barley for forty-six years in succession, from 1852 to' 1897 

 inclusive, and on which each plot has been year after year 

 subjected to some one kind of manurial treatment. Thus were 

 obtained soils about whose history and whose fertility very exact 

 information was attainable. The soils were submitted to analysis 

 by using a solvent consisting of a 1 per cent, citric acid solution. 

 Such a solution is found to yield instructive information in the 

 case of manures, and it approximates fairly closely to the average 

 acidity of plant-root sap. These samples of soil were taken in 

 the autumn of 1889, after thirty-eight crops of barley had been 

 removed. Table VII. (a) gives a list of nine plots out of a total of 

 twenty-two submitted to analysis, with the description of manure 

 applied to each. 



TABLE VII. (a). — Kothamsted Experiments. 



Particulars of Manures applied for the Growth of Barley, for 38 years in 

 succession : 1852-89. 



Plot Nos. 



Manures applied every year 



1,0 No manure 



2, O Superphosphate alone 



3, O Potash, soda, and magnesia (no phosphates) 



4, 0 Superphosphate, potash, soda, and magnesia 



1, A Ammonium salts alone 



2, A Ditto, and superphosphate 



3, A Ditto, and potash, soda, and magnesia (no phosphates) 



4, A Ditto, and superphosphate, potash, soda, and magnesia. 



'7-2 Farmyard manure 



This table shows that plot 1 0 received no manure ; plots 

 2 0, 3 0, and 4 0 received different mineral manures ; plot 1 A 

 received ammonium salts alone ; plots 2 A, 3 A, and 4 A received 

 a similar quantity of ammonium salts with various mineral 

 manures in addition ; and plot 7-2 received farmyard manure 

 at the rate of 14 tons per acre every year. 



Thenext table — VII. (b) — belongs to the same experiments, and 

 shows the total amount per acre in the top 9 inches of soil of potash 

 and phosphoric acid present in each plot of land, with the 

 quantity that was found soluble in a 1 per cent, solution of citric 

 acid; also the average produce per acre of barley grain and 

 barley straw that was grown on each plot. 



