'I ll K I'.IMADHALK WHEAT SOILS. 
101 
rately) have 1 >♦ < ■ n likewise applied annually. Here the average yield 
of grain is aearly double that of the former group, while the straw is 
more than two and one-fourth times as great. 
Then we have the plat which has received continuously an abun- 
dance of phosphatie and other mineral manure, but no nitrogen. Its 
yield is now poorer on the average than even the first group, for it is 
Buffering from nitrogen starvation — shown even more strongly in the 
low st ia\v yield than in the low yield of grain. The yield of both 
grain and straw, though less than t he average yield of the first group, 
is nevertheless better than that of the anmanured plats :) and 4 
included in it, which are suffering from both nitrogen and mineral 
starvation. But its yield of grain is only half thai of the group of 
soils supplied annually with nitrogen as well as minerals, and its 
yield of straw is nol mueh more than one-third. Since it has received 
practically the same supply of phosphatie manure per acre as this 
group, we should (apart from the information derived from analyses 
of the crops) expect to find an additional accumulation of phosphates 
in this plat over and above that found in group 2. 
Then we have the farmyard manure plats, the one dunged liber- 
ally for fifty years leading the way with a yield well above that of any 
of the other groups, both as regards grain and straw, and the other 
subjected to this liberal treatment for nine years only, but still, in 
virtue of its comparatively newly acquired fertility, giving a better 
yield than the average of the chemically treated plats, though not so 
good a yield as the completely manured plat L3. 
The differences in phosphoric-acid contents that one would be led 
to expect from t he aforesaid consideral ions are qualitat ively apparent 
in the figures for total phosphoric acid. Thus the second group 
shows greatly more phosphoric add than the first group. Again, on 
the other hand, it show s Less than plat 5, Intermediate is the Long- 
dunged plat, while the plat more recently brought under dung treat- 
ment is intermediate between th«' first and second group. 
But these differences in total phosphoric acid, significant as they 
clearly are, in soils from the same field, would convey, apart from a 
priori knowledge of their origin and of their circumstances, no such 
informal ion as to BUggest the profound differences really existing in 
tin phosphatie condition of the soils. 
To make t his more clear, t he figures are best reduced to a simple 
proportion, taking the average quantity of phosphoric acid in the 
first group as unity. We then have:* 
Numlier of plats. 
Mode of manuring. 
plats receiv- 
ing no phos- 
phates. 
Four plats 
Pive plats 
One plat . 
No phosphates 
Phosphates and nitrogen, with and without alkaline salts. 
Phosphates and alkaline salts only — 
1.00:1 
1.65:1 
l.sl:l 
1.78:1 
1.36:1 
Do 
Do 
Dung :Vi years 
Dung 'J years. 
