24 WHEAT PRODUCTION IN NEW ZEALAND 



though the variations are not distinct. Consequently 

 we should expect to find different methods of cultivation 

 and different kinds of seed sown, but such is by no 

 means the case, and here then is one reason for a 

 declining industry. 



(ii) Use of Fertilisers. No greater evidence of the 

 operation of the law of diminishing returns can be found 

 than that the problems of artificially fertilizing the land 

 are claiming attention in many countries of the World. 

 It is not within my purpose in this paper to indulge in 

 the technicalities arising from the more detailed aspect 

 of the subject. To the chemist and agriculturalist will 

 be left the consideration of the compositions of various 

 manures ; but for the purposes of considering the whole 

 economic view it is often incumbent upon the economist 

 to enter the domains of the physical and natural sciences. 

 Hence the few speculations made upon the advantages 

 of fertilisers must not be looked upon as a treatment of 

 the chemistry of the subject. 



Two methods of adding plant food to the soil are at 

 once apparent. (1) Direct: (2) Indirect. 



(1) Direct. The greatest problem with which the 

 farmer has to contend in this respect is the provision 

 of suitable quantities of nitrogen in the soil. It is the 

 superiority in this respect which the Russian black soils 

 and the virgin soils of Canada and the United States 

 enjoy that makes them the home of wheat growing. 

 Zealand soils generally are not of a black free nature, 

 but contain comparatively low proportions of nitrogen, 

 and when farmers realise this, better prospects will be 

 in view. For the production of wheat on the most 

 efficient basis, the soil requires now in most countries, 

 in addition to nitrogen, complete mineral manures 

 containing phosphorus, calcium, and potassium. 



Naturally, manuring for wheat was for many years 

 thought to be quite unnecessary in New Zealand, because 

 of the residual fertility of the soil. When, afterwards, 

 manuring was commenced, the English practice in the 

 application of nitrogenous manures was copied, and was 

 found to be non-effectual, or at least uneconomical. 



