GENERAL CONDITIONS IN NEW ZEALAND 35 
This table clearly shows that the soils of the wheat 
producing areas of New Zealand contain the ingredients 
necessary for the economical and efficient growth of 
wheat to a remarkable degree. Few other countries 
can compare with New Zealand in this respect. Russian 
soil is perhaps richer, while the United States of America 
wheat belt possesses many similar qualities. European 
areas do not surpass the Dominion in natural fertility, 
while Australia and Argentina are on the whole out- 
classed by her. 
Thus the conclusion is forced upon us that New 
Zealand possesses a differential advantage from the fine 
qualities and equal distribution of her soil ingredients. 
After considering the advisability of making a systematic 
soil survey of the soils of the Dominion, we shall turn 
our attention to an investigation into the possibilities 
of improving the natural fertility of the soil by the use 
of fertilisers, both direct and indirect. 
(b) A Soil Survey—In every country water supply 
is the most important factor governing the productivity 
of the soil. Given a sufficiency of water, the chemical 
constitution of a soil is usually of secondary importance. 
The textural classification of soils into sands, loams, 
clays, ete., is essential in defining their cultural character, 
and, if this classification is accompanied by the water 
requirements of the soil, we gain some idea of the agri- 
cultural value of the land. 
The factors controlling productivity are of two groups 
—water supply, and chemical constitution of the soil— 
and if it is necessary to assess the agricultural value of 
the land, we must classify the soils according as they 
eonform to or differ from types, and group the types 
according to their water requirements. This latter 
requirement is necessary because of the fact that in any 
locality with land of a uniform chemical composition 
and with a uniform rainfall, the supply of water may 
be excessive in one part and defective in another. The 
