360 The Woburn Pot-Culture Experiments , 1907-8. 
in soils and the consequent effect on crops. The main point 
having been established, that the increase of magnesia produces 
a change in the nature of the wheat grain and on the root 
development of the plant, the Pot-culture Experiments are now 
being extended to studying the effect of natural minerals — such 
as dolomite — in which magnesia presents itself, and which may 
be available for use in practice. Dolomite, both in its ground 
state and as burnt into magnesian lime, is being tried, and in 
comparison with ordinary limestone and with burnt lime (not 
magnesian), as also with magnesium carbonate, magnesium 
sulphate, &c. The practical question as to whether magnesian 
limestone and magnesian lime have or have notan injurious 
effect, and are for that reason to be rejected, has an important 
bearing on practical agriculture. 
Another set of experiments has reference to the advantage 
or otherwise of giving nitrogenous manures to Fen soils. The 
latter are naturally very rich in nitrogen, but the evidence 
obtained from the Pot-culture work at Woburn goes to show 
that this nitrogen is in a very unavailable condition, and that 
easily assimilable nitrogen may usefully be added. 
The experiments on green-manuring have been advanced 
another stage, and while it has been shown that the question 
as between tares and mustard as a preparatory crop for wheat 
is largely one of soil texture and consequent water require- 
ments, there are other points involved, it is believed, which 
the continuation of the inquiry will, it is hoped, elucidate. 
A new subject was taken up in 1908 at the Pot-culture 
Station, in conjunction with the Field Experiments on the same 
subject, and described on pages 351-2 of this Report — the value 
of Professor Bottomley’s “ nitro-bacterine ” for inoculating 
leguminous crops. The general results of these experiments 
at the Pot-culture Station were of a negative character. In 
some cases the inoculated crops were slightly better than those 
not inoculated, in others the reverse was the case, but the 
differences between the two sets were practically immaterial. 
Other trials were made with Professor Bottomley’s culture 
for non-leguminous crops, but the material was received too 
late to make the trials really comparable, and they will be 
repeated in 1909. 
Experiments on the eradication of wild onion have been 
continued at the Pot-culture Station, and this jointly with 
others on a practical scale on farm fields. The evidence thus 
far obtained goes to show that there is little hope of any 
application of “ chemicals ” to the soil being really effective, 
but that the remedy really consists in the alteration of the 
texture and condition of the soil. In the field work alluded 
to a marked diminution of the wild onion has been brought 
