5y 



held, each likewise containing 2,000 hills, were plowed in May to a 

 depth of five inches, and, like the stubble plot, were disked once and 

 harrowed. Another experimental plot of the same size, known as the 

 cultivation plot, was plowed May 12 to a depth of seven inches, 

 disked three times, on the 15th, 19th, and 22d of May, the disk work- 

 ing the last time to a depth of four to four and a half inches, and har- 

 rowed. All these plots were planted on the 22d and 23d of May. The 

 following table gives Mr. Sanders's data of yield obtained November 

 15, when the crop from these plots was harvested. 



Comparative Yield of Corn in Check Plots, Cultiva- 

 tion Plot, and after Oats, 2,000 Hills 

 EACH, Galesburg, 1908 



Compared with the average yield of the checks, the plot in the 

 fall-plowed oats stubble bore nearly 6 per cent more stalks than the 

 checks, 18 per cent more ears, and 25 per cent more corn by weight. 

 Compared with the cultivation plot, the differences in favor of the stub- 

 ble plot were nearly 3 per cent in the number of stalks, more than 11 

 per cent in the number of ears, and more than 13 per cent in the 

 weight of the crop. 



There are several unknown elements capable of affecting this 

 comparison, for we know nothing of possible differences between the 

 oats and corn fields in respect to their fertility and other conditions due 

 to their previous cropping and treatment, and we are also ignorant of the 

 possible influence of differences in the weather at the times when the 

 plowing was done in fall and in spring. There is additional evidence, 

 however, that the advantage of the stubble plot was due, at least in part, 

 to the smaller number of root-lice harbored by it early in the season. 

 Twenty infested hills were dug from each of these plots and all the ants 

 and aphids contained in them were counted on the 9th of June, and again 

 on the 15th of that month, and similar counts were made from ten in- 

 fested hills dug up in each plot June 23 and July 5. 



