32 AGRICULTURE 



areas of Canada and the United States, for 

 instance, the annual rainfall does not exceed 

 10 inches, a quantity quite insufficient to 

 meet the requirements of such a crop as 

 wheat. In these districts it is now a common 

 practice to crop the land only once in two 

 years, the intervening year being utilized 

 for the purpose of collecting and storing water 

 in the soil for the use of the crop during the 

 succeeding year. During the year of bare 

 fallow the field is frequently stirred to the 

 depth of 3 or 4 inches by the cultivator and 

 harrows, and may once or twice be shallow- 

 ploughed, the result being that the loose, 

 dusty condition of the surface soil prevents 

 water rising to the surface, and escaping 

 into the air. The rains and snows of one 

 year are thus added to the atmospheric pre- 

 cipitations of the next, and by this means 

 crops can be grown in alternate years under 

 conditions that would otherwise prevent 

 their being grown at all. 



In the drier parts of Britain much of the 

 attention of the cultivator should be given 

 to the conservation of soil moisture. Not 

 only should ground not yet under a crop be 

 lightly cultivated in spring, but during 

 summer also, when a crop is being grown, 

 attention should be given to careful inter- 



