NOVEMBER 30, I1916| 
gredients, are peculiar to, and distinctive of, that area. 
For example, the well-defined culture-complex 
which is commonly called Neolithic (see Nature, 
May 11, 1916) is characteristic of Europe and 
the immediate neighbourhood; nor, in fact, was 
it synchronous or of identical composition in different 
parts of Europe. But when one passes to the East or 
the South, although all the ingredients out of which 
the European Neolithic was compounded may be found, 
there is no phase of culture which can justly be labelled 
Neolithic in the same sense as the term is applied in 
Europe. 
THE BRITISH ASSOCIATION AT 
NEWCASTLE. 
SECTION M. 
AGRICULTURE, 
ApprEss (ABRIDGED) By E. J. RusSSELL, 
D.Sc., PRESIDENT OF THE SECTION. 
I am going to deal to-day with the possibilities and the 
prospects of increased crop production, which, both in 
its narrow aspect as a source of national wealth, and 
in its wider significance as the material basis of 
rural civilisation, must always remain one of the most 
important of human activities. 
The main obstacles to increased plant-growth lie in 
the climate and in the soil. Climate apparently cannot 
be altered; so we have to adapt ourselves to it by 
growing crops and varieties suiting the conditions that 
happen to obtain. But soil can be altered, and it is 
possible to do a good deal in the way of changing it 
to suit the crops that are wanted. 
On light soil the two great obstacles to be overcome 
are the lack of water and the poverty in plant nutrients. 
Both arise from the same cause, the lack of colloidal 
substances, such as clay and humus, which have the 
power of absorbing and retaining water and plant 
nutrients. There are two ways of dealing with the 
problem; one is to get round it by increasing the 
depth of soil through which the roots can range, and 
the other is to remedy the defect by adding the neces- 
sary colloidal substances—clay, marl, or organic 
matter. In practice it is not possible to add sufficient 
to overcome the defect entirely, and therefore both 
methods have to be used. 
Depth of soil is perhaps the most important single 
test that can be applied to light sands. If the soil is 
shallow, and is underlain by solid rock, pebbles, or 
gravel, the case has hitherto been hopeless, excepting 
where the climate is persistently moist. I know of no 
instance of successful treatment in tolerably dry re- 
gions; the areas are generally left alone. They form 
picturesque heaths, some are used as rabbit-warrens 
or golf courses, some are recommended for afforesta- 
tion. 
If the rock, instead of being solid, is simply a thin 
layer separating the sand above from a great depth 
of sand below, then the improvement can be effected 
by removing it. 
Once the light soil is made deeper it can be still 
further improved. The most permanent improvement 
is to add clay, or preferably nvarl; this used to be 
done in many parts of England, but it now only sur- 
vives on certain fen or peaty soils. 
The usual method of increasing the absorptive power 
of light sandy soils is to add organic matter, 
by dressings of farmyard manure, by feeding crops 
to sheep on the land, or by a method that wants much 
further investigation, ploughing crops or crop residues 
straight into the soil. But the organic matter dis- 
appears at a very rapid rate, so that the process needs 
repeating in one form or another every second or third 
NO. 2457, VOL. 98] 
OPENING 
NATURE 
259 
year. The addition of organic matter must generally 
be accompanied by the aadition of lime or limestone, 
otherwise the soil may become * sour ’’—a remarkable 
condition, detrimental to plant-growing, but not yet 
fully understood by chemists, and therefore more easily 
detected by the vegetation than by analysis. Few 
light-land farmers use lime or challx as regularly as 
they should for the best results. 
Further, it is necessary to add all the plant-nutrients, 
for sand is usually deficient in these, excepting in 
places calcium phosphate. The common English prac- 
tice is to import feeding-stuffs to be eaten by sheep 
on the land, so that the great proportion of the nitrogen, 
potash, and phosphates thus brought on to the farm 
shall get straight into the soil. This is not sufficient, 
however, and artificial manures should be used as well 
and far more extensively than at present; nitrogen, 
potash, and phosphates are all wanted. 
These additions do not end the matter. Light sandy 
soils are very prone to weeds, and _ constant 
cultivation is necessary to keep them down. For- 
tunately the cultivation serves another purpose as well; 
it helps to retain the moisture content of the soil. 
Thus the management of a light sandy soil is a con- 
stant struggle; it demands constant surface cultiva- 
tions, frequent additions of fertilisers, of organic 
matter and lime, and periodical deep ploughings to 
check any tendency to pan formation. When all this 
is done these light soils become very productive; they 
will grow almost any crops, and they can be cultivated 
easily and at almost, but not quite, any time. One 
of their chief defects is that cereal crops do not produce 
so much grain as might be expected; in the words of 
the practical man, they will not “corn out.” This 
phenomenon requires further investigation. 
On the other hand, neglect in any of these directions 
soon leads to failure. 
These are the conditions for the successful manage- 
ment of light soils; how far can they be attained? 
This is a purely economic question. It is obvious that 
success is only possible if the gross returns are suffi- 
cient to cover the costs. Now, a very great deal of 
experience has shown that the ordinary farm-crops— 
wheat, barley, swedes, etc.—do not bring in sufficient 
gross return to encourage good farming. Numerous 
instances occur on the tracts of light Bagshot sands. 
Some of the old four-course farms still survive— 
wretched little affairs, the tenants of which are con- 
stantly struggling against chronic poverty. Again, 
considerable areas of light land in Hertfordshire caused 
their cultivators to go bankrupt in the ‘nineties when 
only these ordinary crops were grown. The old Town- 
shend and Coke method of feeding sheep on the land 
is satisfactory, but it requires the triple, and not very 
common, qualifications of capital, good knowledge of 
sheep, and of crop management. The situation in 
Hertfordshire was saved by the potato-crop, which, on 
these farms, brings in a gross return of 25]. or more 
per acre, against a return of 71. from wheat at pre- 
war prices. Of course, the expenditure on potatoes is 
much greater than on wheat, but that does not matter ; 
the point is that the expenditure has to be incurred 
in any case if the land is to be kept in good cultiva- 
tion, and potatoes bring in the necessary return, while 
wheat does not. Potatoes are the commonest of 
money-finding crops, but they are not the only one. 
Greens are in some places very successful, bringing 
in 17/1. or more gross return. In North Kent various 
market-garden crops are used. In parts of Norfoll< 
blue peas have answered satisfactorily. Clover-seed is 
a useful adjunct in places, but it is not sufficiently 
trustworthy as the chief money-maker. 
It is not necessary to take the money-finding crop 
very often; once in four years may prove sufficient. 
But the system is capable of considerable intensifica- 
