"Another idea that I pondered over a great deal was the state- 

 ment that tillage makes a soil more fertile. Experience had taught 

 me that the better I prepared my com ground and the more I culti- 

 vated, the better the crop ; but I had supposed that this was merely 

 because the soil was made more mellow and the roots had a chance 

 to spread out further in the soil. Little by little I have come to 

 understand that good tillo/je helps to rruike di<festihle^ w OA^ailuhh, 

 some of the to iigh plant-food lohich lies in the soil. 



" When you published your first three lessons on the soil and its 

 fertility, I wish yon had directed the printer to put in large letters 

 the idea that t?ie soil is a laboratory ichich rnust he kepjt in good 

 repair, so that ' cliemical activities,' as you say, can go on rapidly 

 and unlock the locked-up fertility. You ought to have made more 

 clear that it is my business to keep the laboratory in repair so that 

 the ' chemical activities ' can go on without liindrance. If you 

 were to ask my idea of a worn-out soil, I should say that it is a case 

 in wliich the farmer has let the soil lah>oratorv jfo to ruin. If this 

 is true, then the problem of restoring fertility is. How can I best 

 put the laboratory in repair ? 



" Thev tell me that soil is made of vegetable matter and rock 

 ground into very fine particles, what I should call stone flour. 

 Please let me say vegetable matter instead of organic matter, for 

 that is the wav I am in the habit of thin kin cf. Yes, thank vou for 

 suggesting humus ; I supjxjse it means much the same thing. They 

 also tell me that by much cropping this vegetable matter will grad- 

 ually pass out. It came to me that this may become exhausted, 

 leaving only the stone flour behind. Stone flour is next thing to 

 clear sand and clear sand is next thing to a granite boulder. I can- 

 not conceive much ' chemical activity ' going on in a boulder. 



"If I am right in this, then the first step for me to take towards 

 promoting chemical activities is to imitate naturae and add more 

 humus to the soil hy plowing under green crojjs. I have been 

 experimenting along tliis line for several seasons and in the main I 

 think this is the first principle in trying to improve worn-out soils. 

 I say ' in the main,' for usually one cannot carry a point by one 

 idea. It seems to me that this often causes the failure of many 

 well-meaning men who would be progressive ; they go on just one 



573 



