CROP PRODUCTION IN" THE GREAT PLAINS AREA. 23 
Dalhart, listing has produced markedly better yields than surface 
planting. At Scottsbluff, Hays, Garden City, and Amarillo there has 
been little difference. At Akron the advantage has been decidedly 
in favor of surface planting. 
THE OBJECTS SOUGHT BY PLOWING. 
The principal objects which are sought by plowing and the subse- 
quent preparation of the soil are to prepare a suitable seed bed for the 
germination of the seed and the early growth of the seedling, to make 
the surface soil more receptive to water falling as rain or snow, and 
to prevent the growth of weeds. It is also important to have the 
surface of the soil in such condition that it will neither blow when 
exposed to high winds nor puddle when subjected to heavy beating 
rains. The latter considerations are of special importance when a 
period of several months intervenes between plowing and seeding, as 
in the case of summer tillage or of early fall plowing for spring-sown 
crops. The surface should then be left in a rough, cloddy, or ridged 
condition and a fine dust mulch avoided. 
DEPTH OF PLOWING. 
The data submitted and discussed in this bulletin show that sub- 
soiling has failed to give the most profitable yields of either spring or 
winter wheat, oats, barley, or corn, at any of the stations where it has 
been tested. These results are in accord with those of other investi- 
gations with deep tillage that have been conducted by the Office of 
Dry-Land Agriculture. The evidence so far obtained from the 
investigations goes to show that nothing is gained by stirring the soil 
to a depth greater than is done by ordinary plowing 8 inches or less 
in depth. 
HOW AND WHEN TO PLOW. 
The comparative average yields from fall and from spring plowing at 
each station for corn, spring wheat, oats, barley, milo, and kafir have 
shown but small differences. As the land requires plowing for all 
annual crops except in those cases above noted, and as plowing is an 
expensive operation, it is a question of great economic importance as 
to how and when this plowing should be done. Much has been written 
upon this subject and many theories have been developed and advo- 
cated, but the investigations conducted in the Great Plains by the 
Office of Dry-Land Agriculture seem to show conclusively that no set 
rule can safely be followed. The best practice seems to be to do a 
good, clean-cut, workmanlike job of plowing to a depth of 4 to 8 inches 
when the soil is in proper condition and the work can be done to the 
best advantage, taking into consideration the most economical dis- 
tribution of labor throughout the year. 
