5°8 
Journal of Agricultural Research 
Vol. XIV, No. ix 
as that of the four not dynamited. The individual yields of the four 
wheat plots following wheat were lost by mixture. There was no differ¬ 
ence in height, stand, or estimated yield. Of the four wheat plots follow¬ 
ing com two were dynamited in 1912. Their yield was 18.2 bushels on 
plot J and 19.2 bushels on plot L. Plot K, not dynamited, yielded 16.2 
bushels, and plot M, not dynamited, 18.2 bushels. This shows an aver¬ 
age gain of 1.5 bushels per acre in favor of the pair of dynamited plots, 
but exactly the same difference is shown between the pairs J-K and 
]>-M that do not differ in their treatment. 
The experiment was continued in 1916 by seeding the north half to 
com and the south half to wheat as in 1914. The season proved un¬ 
favorable, and these plots were badly damaged by rabbits. As no 
differences were apparent that could be attributed to the use of the dyna¬ 
mite, the yields were not determined. 
deep tillage by the use of special plows 
The land used in the deep-tillage experiment is a block 37 rods long 
north and south and 10 rods wide, divided into 16 plots 10 rods long 
and 2 rods wide containing yi acre each. Bare, cultivated alleys 4 feet 
7 inches wide separate the plots. The land was broken from prairie 
sod during the summer of 1907, but a record of its treatment for the 
seasons of 1908 and 1909 is not available. During the season of 1910 
the west half of all the plots produced a light crop of oats, and the east 
half was planted to cultivated crops of com, sorghum (A ndropogon sorghum ), 
and sunflowers (Helianthus annuus). The soil is a sandy loam, in¬ 
creasing in heaviness toward the north. The north half of the block 
slopes slightly to the north. The 16 plots are designated by the letters 
A to Q, reading from the south. 
In the spring of 1911 an experiment was outlined to test the effect 
of deep tillage, as compared with ordinary plowing, for spring wheat 
and com in different combinations of wheat and corn and the two 
tillage depths. Eight of the sixteen plots were to be deep-tilled and 
eight plowed in the ordinary manner each year; eight plots to be 
cropped to wheat and eight to corn in such manner as to afford differ¬ 
ent combinations of these crops and tillage methods. 
The Spalding deep-tilling machine used in this experiment was received 
too late to prepare for wheat in 1911. The eight plots to be planted 
to com were plowed on May 17, four of them deep and four shallow, as 
called for in the outline. The corn crop for this year follows the out¬ 
line as regards depth of tillage, but was on land which was uniform with 
reference to crop sequence. The eight plots that should have been in 
wheat were fallow during the summer. They were plowed on July 
13, four of them with the ordinary plow and four with the deep-tillage 
machine. Winter wheat was sown in the fall on four of the fallow plots 
and four of the plots that had been in com. The preparation for the 
