5 



SCIENTIFIC A GRICUL TURE. 



107. Deep plowing also brings new earth to the 

 surface, and forms a deeper soil, altering its physical 

 and chemical properties and promoting the growth 

 of vegetation. Should the sub-soil be less fertile 

 than the surface, which is generally the case, care 

 should be taken not to bring much of it to the sur- 

 face during any one season. After the soil has been 

 deepened sufficiently, the sub-soil should only be 

 stirred by means of the sub-soil plow. 



108. A very economical and effective method of 

 sub-soiling is to run a plow with a long narrow shovel 

 immediately behind the common turn-plow. The 

 shovel can be made by a common blacksmith, and 

 be easily repaired. The expense of sub-soiling can 

 thus be made very light, while the advantages, espe- 

 cially in heavy soils, are sure to be recognized after 

 a thorough trial. 



109. There are other mechanical means of im- 

 provement, such as the mixing of stiff clays with 

 light, sandy soils, and the opposite, which are prac- 

 tised with advantage in thickly populated countries, 

 but which cannot be profitably employed by us in 

 the cultivation of wheat, com, cotton, and tobacco. 

 The main object is to secure the greatest amount 

 of improvement at the least expense. An unset- 

 tled feeling frequently prevails among farmers and 

 planters in a new country which operates strongly 

 against anything like permanent improvement, and 

 tends to produce careless cultivation and rapid ex- 

 haustion of the soil. The abundant supply of new 



