was good while that of the May plantings was very poor. At husking 

 time the yield of 1,800 hills taken from the twenty central rows of each 

 plot was separately weighed, with the result that the several plots 

 showed yields per acre as follows: Plot 9 (thrice disked), 59.75 

 bushels; Plot 10 (twice disked), 60.73 bushels; Plot 11 (once disked), 

 64.7 bushels. In other words, the additional diskings beyond the first, 

 seemed to reduce the yield by 6.1 per cent for one additional disking, 

 and by 1 .7 per cent for two additional diskings. It would seem that 

 under the circumstances of this experiment, some agricultural disad- 

 vantage followed the additional diskings which more than counter- 

 balanced the advantages due to a repeated breaking up of the nests of 

 the ants. Unfortunately no fair check plot was made for contrast 

 with tlie three plots used in this experiment. It was assumed at the 

 time that the checks of the original May planting would serve for this 

 planting also — a supposition disappointed by the great difference in 

 the weather of the two periods. 



Effect of Fall Plowing compared with that of 

 Spring Plowing 



For the purpose of determining whether fall plowing and disk- 

 ing of an infested field was to be preferred to spring treatment, three 

 plots, Nos. 1, 2, and 3, in this Galesburg field, were plowed in the fall 

 of 1909, No. 3 to a depth of four inches only, and the others six 

 inches deep. Plot 3, plowed October 29 and 30, received no further 

 treatment in the fall ; but it was necessary to disk it once in spring in 

 order to loosen up the plowed ground, and afterwards to harrow it 

 before planting. Plot 2 was plowed October 29, and disked three times 

 in succession in fall, and disked once in spring and harrowed also as 

 an immediate preparation for the planting of the corn. Plot 1 was 

 disked three times in fall, and rolled immediately after each disking, 

 and it was also disked twice in spring. Plot 6, a spring-plowed check 

 upon these fall-plowed plots, was broken up four inches deep May 4, 

 and harrowed once before planting. All these plots were planted on 

 the 11th of May. Plots 1, 2, and 3 were kept until the first of June, 

 when the ground they occupied was plowed and replanted for an- 

 other experiment, already described, as plots 9, 10, and 11. 



In the meantime a row of 90 hills of corn was dug from the cen- 

 tral part of each of these four plots on each of five different dates. 

 May 23, 25, 28, 30, and June 1, amounting to 450 hills for each plot; 

 and the usual counts were made each time of the number of hills in- 

 fested with ants, the total number of ants and aphids respectively, 



