80 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
potash in the soil, and of 2,508 lbs. and 4,778 lbs. per acre of 
total phosphoric acid, appears from these results to be immaterial 
as a measure of present soil fertility, notwithstanding that the 
degree of solubility of each constituent is largely increased on 
the different plots according to the manure employed. As no 
nitrogen has ever been applied to the plots of the mineral 
series (1 to 40) there has been no strain on the natural resources 
of the soil, and consequently the barley crops obtained have been 
small. 
From the next group of plots, 1 A to 4 A, we get some valuable 
information. To each of these portions of ground ammonium 
salts have been added to the other manures. (See Table VII. [a].) 
The total amount of potash is seen to range from 35,845 lbs. to 
43,301 lbs. per acre ; of this quantity the soluble part ranges 
from 50 lbs. to 1,029 lbs., showing that plot 3 A has 200 times 
more available potash than plot 1 A, but, owing to the lack of 
sufficient soluble phosphoric acid, the yield of barley is but 
2 bushels per acre in excess of plot 1 A. The phosphoric acid 
ranges in total amount from 2,452 lbs. to 4,602 lbs. per acre, 
the soluble portion from 152 lbs. to 1,264 lbs. per acre. The 
produce of barley grain and of barley straw is seen to be about 
doubled from the previous series; but in plot 1 A, receiving 
ammonium salts alone, there is a starvation of the two mineral 
constituents, potash and phosphoric acid, notwithstanding the 
large amounts in the soil; while in plot 3 A, receiving the nitrogen 
and potash, but no phosphates, there is a starvation of phos¬ 
phoric acid, with a consequent falling-off in the crop grown. 
Plot 7, which had received 14 tons of farmyard manure per 
acre for thirty-eight years, amounting to the enormous quantity 
of 532 tons of manurial material, but made up very largely of 
organic matter and water, shows an accumulation in the soil of 
33,374 lbs. of potash per acre, of which 669 lbs. only is soluble. 
Phosphoric acid shows 3,669 lbs. per acre, of which 932 lbs. are 
soluble. The returns of corn and straw on plot 7 show that 
the accumulated residue of organic nitrogen in the soil enables 
the crop to be maintained at a high standard, notwithstanding 
that the amounts of potash and phosphoric acid in the top 
9 inches of soil are lower than in the soils receiving artificial 
manures. But doubtless the improved subsoil on the dunged 
plot would have much to do with its increased produce. 
