156 TwENTY-FlBST BlENNIAX, EePOET 



to the land the farm manure equivalent of the crops re- 

 moved and by the cultivation of leguminous crops, and 

 the use of catch crops, cover crops, and crop residues. 



Fifth. That the use of complete fertilizers is neither 

 economical nor is it conducive to a condition of perma^ 

 nent soil fertility for the reason that the apparent good 

 results obtained following the use of such soil amend- 

 ments are frequently due to stimulation of plant growth 

 which results in the removal from the soil of an excess 

 of plant food, thereby leaving the soil in a more de- 

 pleted condition than it was previous to the application 

 of the fertilizer. 



Sixth. If the plot tests, or the results obtained on 

 an experimental field or the chemical analysis of the soil 

 indicate a deficiency of potash or phosphoric acid in any 

 soil, then these "elements, one or both, must be supplied 

 in the cheapest available from and in quantities sufficient 

 to meet the food requirements of a number of crops/ The 

 soils of Kentucky outside of the Blue Grass region are 

 deficient in phosphorus as shown by chemical analysis, 

 plot tests and experijtnents on our experimental fields, a 

 fact that explains the use of increasing amounts of acid 

 phosphate in various counties of the State. In order 

 to obtain any one of these plant foods, the farmer should 

 not be compelled nor encouraged to buy other plant foods 

 that he does not require. 



Lastly, I may say that these have been the teachings 

 regarding soil requirements and the use of soil amend- 

 ments endorsed by the Kentucky Agricultural Experi- 

 ment Station and by other experiment stations and by 

 prominent agronomists generally for the last five or six 

 years. As director of the Kentucky Agricultural Exper- 

 iment Station, I am glad, therefore, to lend my endorse- 

 ment to the teachings set forth by Professor Roberts in 

 this bulletin. In fact, I can heartily commend this bul- 

 letin to the farmers of the State and to those who may 

 be interested in our agricultural prosperity as being de- 

 cidedly the most scientific and helpful publication ever 

 issued by the Kentucky Agricultural Experiment Sta- 

 tion on the general subject of soil fertility and the ra- 

 tional use of soil amendments. 



