ACTION OF ELEMENTS OF SOIL. 87 



been too long wrestling, and trying to get each oth- 

 er down, at arms' length, and now grappling in side- 

 hug, they find the closer the embrace, the longer 

 they stand. So it should be, theory and practice 

 should mutually support each other. 



129. The theoretical and the practical farmer aim 

 at one common object. The latter is employing 

 certain means to effect certain ends ; the former un- 

 folds the laws of nature, which limit and control the 

 operations which are performed to effect that end. 

 Theory may teach a rational and successful practice; 

 this last may lead to a rational theory. But without 

 a knowledge of the elements of soil, and of their 

 mutual action, which is to be learned from chemis- 

 try only, the practical application of science to agri- 

 culture, is but the dream of enthusiasts. 



130. How do the elements of soil act ? The an- 

 swer involves two important considerations. 1st. 

 The mutual chemical action of the elements of soil, 

 their organic and inorganic parts on each other ; and 

 2d. This action, as influenced and modified, by the 

 presence of living, growing plants. 



131. The elements of soil, are silicates, salts and 

 geine. The silicates, as such, have no tendency to 

 react on each other. These are gradually decom- 

 posed by the action of the air. The great agent in 



