II. 



CHAPTER II. 



CLIMATIC REQUIREMENTS. 



The term climate, in its broadest sense, implies all the changes in the 

 atmosphere which sensibly affect one's physical condition. — Humboldt. 



20. Climate. — The profits from the cultivation of the soil, CHAP, 

 and in relation to these the preference given to certain crops, 

 depend perhaps more on the extent of the market for such 

 products than on the quality of the soil and the climatic 

 condition within the geographical area of agricultural pro- 

 duction (Davis, 2). 



Hann and Ward (1) define climate as meaning the sum 

 total of the meteorological phenomena that characterize the 

 average condition of the atmosphere at any one place on the 

 earth's surface. That which we call weather is only one phase 

 in the succession of phenomena whose complete cycle, recurring 

 with greater or less uniformity every year, constitutes the 

 climate of any locality. 



21. Factors which Limit Distribution. — The known facts 

 of distribution of maize as a crop lead us to inquire what 

 factors limit that distribution. These have an important 

 bearing on the question of the world's future supply, and more 

 particularly on the problem of South Africa's future share in 

 the world's trade. 



Maize seems peculiarly sensitive to climatic variations, 

 and these furnish the principal limiting factor of distribution 

 of the crop. The variations referred to include temperature, 

 sunshine, amount and incidence of rainfall, and length of 

 growing season. Geographic features and the character of the 

 soil are also important. Only when these several factors are 

 suitably combined does the culture of maize become commer- 

 cially successful ; the absence of any one of them may limit 

 production on a large scale. 



