484 
Journal of Agricultural Research 
Vol. XIV, No. II 
It is mistaking or failing to recognize the purpose of plowing that 
leads to the belief that its efficiency increases with its depth even though 
that depth be extended below all practical limits of cost and effort. 
Plowing does not increase the water-holding capacity of the soil, nor the 
area in which roots may develop or from which the plants may obtain 
food. Plowing removes from the surface either green or dry material 
that may encumber it, provides a surface in which planting implements 
may cover the seed, and removes or delays the competition of weeds or 
plants other than those intended to grow, and in some cases by loosening 
and roughening the immediate surface checks the run-off of rain water. 
All these objects are accomplished as well by plowing to ordinary 
depths as by subsoiling, dynamiting, or deep tilling by any other method. 
There is little basis, therefore, for the expectation of increased yields 
from these practices, and the results of the experiments show that they 
have, been generally ineffective. 
EXPERIMENTS WITH SUBSOILING IN THE GREAT PLAINS 
There are here reported results of subsoiling at 12 stations of this 
office in the Great Plains area for a total of 66 station-years, or an average 
of s l A years at each station. From four to seven crops have been grown 
each year at each station. The crops under trial have been spring 
wheat, winter wheat ( Triticum aestivum), oats ( Avena saliva), barley 
(Hordeum spp.), flax (Linum usitatissimum), com ( Zea mays), kafir, milo, 
broom com, sorghum (Audropogon sorghum), and cotton ( Gossypium 
spp.), as shown in the results from the individual stations. 
The length of time covered and the wide range of climatic conditions 
encountered in these experiments make the results representative of 
the widest range of conditions likely to be experienced in the region. 
Figure 1 is a map of the Great Plains, showing the location of the 
field stations at which experiments have been conducted. 
method op work 
The results with subsoiling are all from continuous cropping of land to 
the crop under study. In this series of continuously cropped plots there 
are in general five methods under trial: Spring plowing, fall plowing, 
alternate cropping and summer tilling, subsoiling, and listing. In this 
study the results from the subsoiled plots, which are designated in the 
fields and notes as the “E plots,” are compared with those from the fall- 
plowed plots, known as the “ B plots.” Except for the subsoiling prac¬ 
ticed on E, these plots are treated exactly the same. They are plowed 
as early in the fall as is practicable after the crop has been removed. 
The plots are plowed to a good depth, the standard being set at 8 inches. 
In addition to the plowing of plot E, a subsoiler is run in the bottom 
of the furrow, loosening the soil to a further depth of 6 to 8 inches, 
