PREFACE 



Liebig said, "Agriculture is, of all industrial pursuits, the rich- 

 est in facts and the poorest in their comprehension." To a large 

 degree this statement is still true, and the chief purpose of this 

 volume is to bring together in convenient form the world's most 

 essential facts gathered from the field and laboratory, and to 

 develop from them some foundation principles of permanent 

 agriculture ; for, as Liebig also truly said, " Facts are like grains 

 of sand which are moved by the wind, but principles are these 

 same grains cemented into rocks." 



While one dare not believe that error has been completely 

 avoided, the facts presented have been checked with all reasonable 

 care, and they may be accepted with the confidence that they are 

 accurately reproduced from the original data. 



Unsolved problems still remain, and some conclusions which 

 seem to be indicated by the data thus far reported may be modi- 

 fied later when more complete information is afforded. The 

 author will always receive with deep appreciation suggested ad-, 

 ditions, modifications, or corrections. 



It is, perhaps, unnecessary to say to the reader that his general 

 knowledge of farm practice is presupposed, and no attempt has 

 been made to include herein a thousand details with which every 

 man experienced in the art of agriculture already is familiar. 



For the sake of himself and children it must be said to the 

 practical farmer that he should encourage the teaching of the 

 science of agriculture in the school, even though he may know 

 much more than the teacher concerning the art of agriculture. 



