330 SYSTEMS OF PERMANENT AGRICULTURE 



ance that no successful farmer in those countries thinks of trying 

 to farm without liberal applications of plant food, especially of 

 phosphate fertilizers, and, as a rule, either farm manure or green 

 manure. Often commercial nitrogen and potassium are also 

 used, in part because of the very high value of farm produce and 

 also because of the low price of potassium salts, Germany's supply 

 of which is estimated to be sufficient to meet the present con- 

 sumption of the world for 190,000 years. 



In comparison with these European records, marked contrast 

 appears in the average crop yields of the state of Kansas during 

 48 years. Professor W. J. Spillman, of the United States Bureau 

 of Plant Industry, has called attention to these statistics in the 

 following words: 



"The following table of figures is interesting: 



"YIELDS PER ACRE AVERAGE FOR STATE OF KANSAS 



"These figures are in general agreement with data collected from other 

 sections of this country. When rich virgin soil is brought into cultivation and 

 farmed without any reference to the conservation of fertility, good yields are 

 obtained for about forty years. Then begins a decline, and the yield ultimately 

 sinks down to a point where there is no profit for the farmer. ... In the case 

 of each of the three crops above mentioned the average yield for the past nine 

 years is slightly greater than for the preceding ten years. This indicates that the 

 Kansas farmer is slowly but surely improving his system of farming. Dairying 

 and the feeding of beef cattle, also hay raising are becoming more prevalent, 

 and there is every reason to believe that before another generation has passed 

 the Kansas farmer will have rehabilitated his soil and have developed suitable 

 systems of farming that will keep Kansas near the forefront in agriculture." 

 (Hoard's Dairyman, May 14, 1909.) 



While the average yields are probably approximately correct 

 and the results are exceedingly striking, in the author's opinion 

 these Kansas results have little significance, because of the enor- 

 mous increase and westward extension of the area put under cul- 



