THE H00^3 FIELD BARLEY SOILS. 
143 
The plats composing the series Ol to 04 have been continuously 
deprived of nitrogenous manure. Plat 01 has received no mineral 
manure either, and is comparable with plat 3 in the wheat field. 
Plats 02 and 03 have received, respectively, phosphates without 
alkalies and alkalies (potassium, sodium, and magnesium salts) with- 
out phosphates. They have no exact counterpart in the case of the 
wheal soils. Plat 04 receives both phosphates and alkalies, and 
corresponds with plat 5 of the wheat field — manured with ' k full min- 
erals' 1 without nitrogen. 
The completely tinman tired plat shows o.owo per cent of nitrogen, 
as against 0.1001* per cent on the unnianured wheat plat (No. :>) at 
about the same dale (1SS1), and is therefore rather poorer. Plat 04 
shows much more than the similar wheat plal (No. 5), namely, 0.1124 
per cent, as against o.ousi. 
This latter result is at first sight very puzzling. We should have 
expected the soil of plat Ol to be poorer than thai of either of the 
plats 1, 2, or 3 of its own section, as was the ease with the correspond- 
ing plats on the wheat field; or even it" the accumulation of roots and 
stubble from its larger crops had caused any slight rescue of nitrogen, 
the difference from such a cause would hardly be very appreciable 
under tlie circumstances, lint we see that it is act ually richer than its 
neighbors by nearly !<><> pounds of nitrogen per acre. We also may 
notice that, in the second depth, this plat also seems to be the richest 
of all the plats of all the sections, except the continuously dunged 
plal ; and in the third depth it is richer even than the dnnged plat. It 
may be seen that this curious plat (04) was also very rich in nitrogen 
in 1 80S; and in — anticipating other results to be subsequently 
discussed — it may be also observed that ii accorded with the general 
rule, viz, that the more the total nitrogen (in a drained soil) the greater 
the quantity of nitrates, for we find, even in February or March, after 
the winter rains, that this plat is distinctly richer in nitric nitrogen 
than either 1, 2, or :> of tin' same series. Sir Henry Gilbert has fur- 
nished me with a key to the mystery of this apparently anomalous 
and unexpected richness iu nitrogen, and I think you will agree with 
me that the explanation is one of remarkable interest. 
Sou are well aware how profoundly continuous manorial treatment 
in one direction or another alters the botanical composition of the 
herbage on grass land. This is exemplified in a most striking degree 
in the Rothamsted grass plats. There we find that an abundant 
supply of phosphates and potash salts tends to increase the non- 
gramineous, and more especially leguminous, vegetation — notably 
clover and trefoils — while on this soil nitrogenous manuring without 
minerals tends to their extermination, because the true grasses can 
live longer and better under such conditions than the clovers, etc., 
and so crowd them out ; and the more the mixture of manures tends 
toward the extreme of purely mineral fertilizers in the one direc- 
