[373] SCIENTIFIC MANUAL. 87 



perature of the soil, enabling vegetation to start forth with 

 full vigor in early spring. 



It is difficult to estimate the importance of such a pul- 

 verization of the soil as to admit of a free circulation of air. 

 Every observant farmer has noticed the difference in the 

 amount of moisture which accumulates by deposition from 

 the atmosphere, during a single summer's night, on soil 

 freshly stirred, and on that covered with a crust which ex- 

 cludes the air. Some idea of the amount of moisture thus 

 extracted from the air may be formed from the accumula- 

 tion of dew upon vegetation. The more finely a soil is 

 pulverized, the greater the surface presented to participate 

 in robbing the atmosphere of its moisture, for the benefit 

 of vegetation. Again, deep preparation and thorough 

 pulverization of the soil enables it to store up moisture, 

 which is yielded up to vegetation during drouth, by capil- 

 lary attraction. Soils thus prepared absorb and retain 

 water from heavy rains, which would run off to the streams 

 from those poorly prepared, carrying with it a portion of 

 the surface soil. Proper preparation, therefore, converts a 

 destructive into a productive agent. 



MINERAL PLANT-FOOD IN THE SOIL. 



This is a question of special importance to the advanced 

 agriculturist, since by availing himself of the light which 

 science has thrown upon plant nutrition, he can not only 

 ascertain what elements of plant-food his soil contains, but 

 may supply its deficiencies in the character, quality, con- 

 dition and ratio needed by different agricultural plants. 



Chemical analysis shows, approximately, the chemical 

 composition of the soil, and quite accurately that of 

 plants. Knowing, therefore, not only the elements of 

 mineral food required by each plant, but the ratio in which 

 they enter, the farmer may supply, for each crop, the min- 

 eral elements that are found to be deficient in the soil, 

 either naturally, or as the result of partial exhaustion, by 

 successive cropping, washing and leaching. 



