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 ).— Kothahsted 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, 0 
Superphosphate alone 
3, 0 
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, 8 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. 
The next 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. 
