THE SOIL 



63 



Rothamsted and Illinois experiments can our problems 

 be solved. 



42. Soil Acidity and Liming the Land. Soil acidity 

 (sourness in soil) is a common problem in the humid 

 climates, especially in the older agricultural regions such 

 as England, the continent of Europe, and eastern 

 United States. Where soils are acid, finely ground 

 natural limestone rock has been found to be the cheapest 

 and most effective. It is applied at the rate of one to two 

 tons per acre, depending upon the degree of acidity in 

 the soil. The 



soils of the arid 

 and semi-arid 

 regions are more 

 likely to be alka- 

 line than acid 

 (alkaline is the 

 opposite of 

 acid) due to the 

 fact that alka- 

 line salts and 

 limestone are 

 not leached 

 away as in 

 humid sections. 

 Limestone i s 

 present in sufficient quantity in most Western Canadian 

 soils, so that this question need give us no concern. 



43. Crop Rotations and Soil Fertility. From Table 

 XIII. we see that barley grown at Rothamsted, England, 

 (Agdell field), in a rotation without fertilization pro- 

 duced as an average of 60 years, 24.7 bushels in the 



25.2 



247 



Fallow Legume One Crop 

 Rotation Rotation System 

 WHEAT 



Fallow Legume One Crop 



Rotation Rotation System 



BARLEY 



Fig. 23. Eothamsted Experiments. 



Chart showing yields of wheat and barley 

 (bushels) in good systems of crop rotation, and 

 in one-crop systems. Figures represent 60-year 

 averages in rotation systems, and 55-year aver- 

 ages in one-crop systems. 



