HORTICULTURAL SOILS. 
79 
TABLE VII. (&)— Kothamsted Experiments. 
On the Growth of Barley for 38 years. Amount of Potash and Phosphoric 
Acid in the Soil, and the quantity soluble. Also produce per acre. 
Plots 
Potash 
Soluble in 
1 per cent. 
Citric 
Acid 
Phosphoric 
Acid 
Soluble in 
1 per cent. 
Citric 
Acid 
Produce per acre 
Grain 
Straw 
Quantities per acre, first 9 inches of s 
soil. 
lbs. 
lbs. 
lbs. 
lbs. 
Bushels 
Cwts. 
1, 0 
! 36,604 
91 
2,503 
139 
16| 
9| 
2,0 
37,918 
165 
4,601 
1,170 
2 If 
10f 
3, 0 
42,848 
925 
3,059 
253 
18 
9f 
4, 0 
43,429 
859 
4,778 
1,360 
22# 
Ilf 
1, A 
35,845 
50 
2,452 
152 
29 
16 
2, A 
36,376 
57 
4,373 
1,073 
42f 
23f 
3, A 
39,637 
1,029 
2,579 
205 
31f 
18 
4, A 
43,301 
753 
4,602 
1,264 
43| 
251 
7-2 
1 33,374 
1 
669 
3,669 
932 
48 f 
29 
The results show at a glance the comparative exhaustion or 
accumulation of both potash and phosphoric acid. It will be 
seen that plot 1 0, to which no manure of any kind had been 
added for thirty-eight years, contained 36,604 lbs. of potash per 
acre, of which only 91 lbs. was soluble, or available to plants. 
Of phosphoric acid there was 2,503 lbs., of which only 139 lbs. 
was soluble. With this small quantity of available plant-food 
per acre it is not surprising that an average produce of 16^ 
bushels of barley grain, and 9| cwts. of straw only was obtained. 
In fact, the wonder is that the land continued to grow corn 
at all. 
The three other plots of the 0 series show from 37,918 lbs. to 
48,429 lbs. of potash per acre, of which there is a range in the 
solubility of from 165 lbs. to 925 lbs. per acre. The amount of 
phosphoric acid ranges from 3,059 lbs. to 4,778 lbs. per acre, 
and the soluble portion from 253 lbs. to 1,360 lbs. per acre; 
the two plots (2 0 and 4 0) receiving the phosphate manure 
each year show from five to six times more available phos¬ 
phoric acid than plot 3 0, which had never received phosphate 
as manure. 
The difference between 36,604 lbs. and 43,429 lbs. of total 
