46 WHEAT PRODUCTION IN NEW ZEALAND 



The yield per acre for the whole province of Canterbury 

 had to be taken because no separate continuous statistics 

 for any district near the meteorological station are avail- 

 able. Probably this is the weak spot in the investigation ; 

 for we should have composite rainfall statistics at several 

 stations in Canterbury, when the yield refers to the whole 

 province. But with the available statistics of rainfall 

 from May to November and average yield per acre, I 

 have obtained over the years 1871-1913 a co-efficient of 

 correlation* of + -251. As the probable error is as much 

 as ! correlation does not seem to be established in any 

 degree. 



The defects in the information as shown above, must 

 be kept in mind, as also the fact that wheat has a wide 

 range of rainfall, so that a country where the average 

 rainfall is about in the middle of this range, as it is 

 in New Zealand, may show wide fluctuations in rainfall, 

 and get comparatively small fluctuations in yield. 



Prom the Agricultural College and Experimental 

 Farm at Lincoln I have been able to get statistics of 

 yield and rainfall there, for the past 12 years (1906-17). 

 The statistics are shown in graph No. 4, but the period 

 is too short to afford a conclusion of importance. The 

 continuance of these records will provide useful infor- 

 mation in regard to the connection between yield and 

 rainfall in Canterbury. It may be observed, however, 

 that the curve of yield per acre moves in sympathy with 

 the curve of "useful" rainfall, though the range of 

 fluctuation is greater. This is suggestive of a close 

 connection between the two series. 



It is interesting to compare similar statistics in Aus- 

 tralia. A graph showing yield per acre for Victoria and 

 composite winter rainfall (May-October) shows a vita] 

 connection between yield and rainfall. This information 

 was supplied to me by the Department of Agriculture 

 for Victoria, and the result in the form of a graph is 

 highly suggestive of a vital connection between yield 



"Correlation is dealt with again in Chapter VI., and is fully 

 explained in Appendix II. 



