WHEAT. 113 



below freezing; eighty-five per cent was grown wheje 

 the average July temperature was between seventy 

 and eighty degrees and sixty-five per cent where the 

 mean annual temperature was between forty-five and 

 fifty- five degrees. We must be careful not to attach 

 too much weight to this, as the soil, particularly its 

 ease of cultivation, has greatly affected the distribu- 

 tion of wheat. However, although there are some 

 noted exceptions, as California, Egypt and India, 

 most of the wheat of the world grows in regions of 

 cold winters. 



The wheat plant for its best development needs to 

 have its early growth in the cool part of the year. It 

 is only early in its growth, during cool weather and 

 slow growth, that wheat tillers. A long period of 

 growth consequent upon cool weather gives it better 

 opportunity to get sufficient plant growth. A cool, 

 prolonged but not too wet spring is probably best. 



According to the investigations of Lawes and Gil- 

 bert, there is a nitrifying agent in the soil which pro- 

 duces a supply of nitrates necessary to produce the 

 crop. Suppose a maximum crop requires twenty- four 

 pounds of nitrates besides those already formed in 

 the soil, and throughout the growing season four 

 pounds are produced per month. Six months of 

 growth would be necessary to produce a maximum 

 crop. If a warm growing season should force the 

 crop to maturity in five months, it would not have 

 enough food to produce a full crop. The loss of ni- 

 trates during wet seasons has been found to be greater 

 and the amount taken up by the wheat smaller. On 

 this account comparatively dry seasons should be 

 favorable for the production of large crops of wheat. 



