328 SYSTEMS OF PERMANENT AGRICULTURE 



first definite information which could serve as a scientific basis 

 for systems of soil improvement. The few records from 1800 to 

 1825 are of little or no value, but the averages from 1825 to 1834 

 show very clearly the application of definite knowledge as com- 

 pared with the averages previous to 1800; while the further marked 

 increase for the ten years ending 1844 clearly shows that the teach- 

 ings of Davy, Bousingault, and Liebig were being applied on the 

 Trebsen estate as well as by Sir John Lawes at Rothamsted. 



The most satisfactory data are from the third German estate, 

 showing lo-year or 5-year averages for practically all of the last 

 century, from which it is plain to see that the first distinct increases 

 date from the publication of Liebig's teachings in 1840. 



While the larger private estates would perhaps be the first to 

 adopt the teachings of science, the records show general increases 

 for both Germany and France. The average yields of wheat of 

 late years for England, Germany, and France are 32.2, 28.0, and 

 19.8 bushels per acre, respectively, or, as a general average, about 

 double the average of 100 years ago. It is safe to credit this in- 

 crease very largely to the use of plant food, including the more 

 general use of atmospheric nitrogen by legume crops during the 

 last quarter century. The average yield of wheat in the United 

 States is 13.7 bushels for the ten years, 1899 to 1908. 



A second factor 1 of much importance in crop improvement, 

 though very subordinate to that of plant food, is the improvement 

 in seed by selection and breeding. A German economist has esti- 

 mated that, as an average, seed improvement has produced a 

 gain of 25 per cent. In exceptional cases, as with the sugar beet, 

 very remarkable progress has been made by breeding, the average 

 sugar content of the beet having been raised from about 4 per cent 

 to 12 per cent or more. 



The following extracts from an address by President Creelman, 

 of the Ontario Agricultural College, to the Ontario Agricultural 

 and Experimental Union, December, 1908, is well worthy of care- 

 ful consideration (Report for 1908, page 62) : 



1 Other factors of improvement are of doubtful consequence, including correc- 

 tion of toxic bodies. Tillage and crop-rotation have been the rule for centuries in 

 old countries. Isolation of such bodies signifies little. The soil is earth's waste- 

 basket, wherein we may find almost every substance, toxic or nontoxic. 



