358 The Woburn Pot-Culture Experiments , 1907-8. 
POT-CULTURE EXPERIMENTS, 1907-8 
(summary). 
As time has gone on, the advantages of having a Pot-culture 
Station, where experiments can be carried on simultaneously 
with Field Experiments, have been made increasingly apparent. 
In the case of certain problems arising out of the Field 
Experiments it has, for instance, been impossible to pursue 
the inquiry further by the ordinary methods of field culture. 
To take an instance — the investigation of the failure of crops 
on the plots continuously treated with ammonia salts. In the 
field one can do little more than apply lime and so restore 
fertility, but the explanation of what has occurred, and the 
investigation of the nature of the poisonous element introduced 
on the land, are matters that have to be followed out in close 
detail, and which require the presence of a chemical laboratory 
and the application of methods of scientific inquiry. Thus it 
is now being sought to ascertain whether the use of tany 
oxidising material will have the effect of neutralising the 
injurious element introduced. The methods of pot-culture 
work allow of the simultaneous trials of a number of different 
materials of this class, so' that their relative effects can be 
studied side by side, whereas in field cultivation this is out of 
the question. 
Another instance of the value of pot-culture work in 
conjunction with field experiment is supplied in the explana- 
tion provided of the seemingly anomalous results found in the 
field in the case of green-manuring (previous to a corn crop) 
with tares and mustard respectively. No continuation of the 
Field Experiments by themselves would ever have given the 
explanation supplied by the Pot-culture work, or have shown 
that the difference lay in the texture of the soil and in the 
relative proportions of water evaporated from the soil in the 
two cases. 
Equally, on the other hand, may investigations begun at 
the Pot-culture Station prove useful guides as to what may be 
advantageously tried on the field scale. The experiments with 
magnesia on corn crops, conducted at the Pot-culture Station 
now for several years past, well illustrate this point. It was 
the remarkable results produced alike on the quality of the 
grain and on the development of the roots of the wheat plant, 
that led to the application of magnesia in the Field Experi- 
ments. The record of these, as given in the earlier part of this 
Report, bears witness to the remarkable influence exerted by 
magnesia on the potato crop (see page 353). 
The Pot-culture work of 1907-8 followed, in main respects, 
the lines of that of 1906-7, but included also new matter in 
