vi PREFACE 



tact that business method is the master, and that 

 teachings of science are the helpmates. 



But even if these facts are fullj' apprehended, 

 the teacher and the farmer are apt to make no 

 distinction between the fundamental and the inci- 

 dental applications of science, or between principles 

 and facts. Therefore, the mistake is often made of 

 teaching how to overcome mere obstacles before ex- 

 plaining why the obstacles are obstacles. How to 

 kill weeds is a mere incident ; the great fact is that 

 good farmers are not troubled with weeds. Rather 

 than to know kinds of weeds, the farmer should 

 know how to manage his land. How to know the 

 weeds and how to kill them is what he calls prac- 

 tical knowledge, but, standing alone, it is really the 

 most unpractical kind of knowledge, for it does not 

 tell him how to prevent their recurrence year after 

 year. The learner is apt to begin at the wrong 

 end of his problem. This is well illustrated in the 

 customary discussions of under- drainage. The pupil 

 or the reader is first instructed in methods of lay- 

 ing drains. But drainage is not the unit. The 

 real unit is texture and moisture of soils : plowing, 

 draining, green -cropping are means of producing a 

 given or desired result. The real subject matter for 

 first consideration, therefore, is amelioration of soil 

 rather than laying of drains. When the farmer has 



