248 SECTIONAL ADDRESSES 
provide the staff and funds so that the survey work is kept ahead of the 
development. 
In a country like this, on the other hand, there is considerable doubt on 
the part of many as to whether the benefits which are supposed to follow 
such a survey will ever be realised. 'The question of suitable crop distri- 
bution and association is well established as the result of generations of 
experience and is not likely to be seriously altered as the result of such an 
investigation. It is claimed that a soil survey on the scale of x inch to 
the mile would be of great importance in connection with manuring and 
in the interpretation of the results obtained by the various methods of 
estimating the available plant nutrients in the soil. Before undertaking a 
survey of such magnitude, it should be pointed out that such a claim would 
require to be based on the results of a wider series of accurate field trials 
than are available at present. At the same time, the importance of survey 
methods from the purely scientific point of view and also in connection 
with land reclamation problems should not be overlooked. 
What the farmer wishes to know about his soil is whether it is adequately 
supplied with nitrogen, phosphates and potash, and whether there is 
sufficient lime present to give a satisfactory soil reaction. These are 
reasonable questions, but it must be admitted that in the past the task of 
the agricultural chemist who had to attempt to answer them was by no 
means easy. Much progress has been made in recent years, and although 
much still remains to be done, more satisfactory replies can now be given 
to the farmer’s questions than was formerly the case. 
With regard to nitrogen, no method exists by which we can judge the 
requirements of a soil as regards this element ; the fact that most soils 
respond to dressings of soluble nitrogenous fertilisers is about as far as 
we can go in the way of prediction. 
At the same time, it must be pointed out that considerable progress 
has been made in the difficult question of the nature of the soil organic 
matter. The recent work of Page in England, Schmuck in Russia and 
Waksman in America (S.C.I. Ann. Rep., vol. xvii (1932), p. 461) has shown 
that the so-called ‘ humic acids’ are in all probability protein-lignin 
complexes. Synthetic products of this type have been prepared and 
agree closely in properties with the humic acids found in soil organic 
matter. 
On the other hand, the lime requirement of a soil can now be given with 
reasonable accuracy by routine methods which are suitable for use on a 
large scale. The question as to whether the dressing of lime which is 
theoretically desirable can be recommended is generally an economic 
rather than a chemical one. 
To determine what the requirements of a soil are with regard to available 
phosphates and potassium is a more difficult matter. The most that can 
be aimed at at present is to be able to say whether the soil is well supplied 
or moderately supplied with these constituents, or is deficient in them. 
The difficulties of discriminating between the available and non- 
available constituents in a soil are obvious. In the first place, the way in 
which plants take up their nutrients from the soil is still a matter of con- 
troversy, and the fact that the soil is a heterogeneous and ever-changing 
