2 BULLETIN 219, U. S. DEPARTMENT OF AGRICULTURE. 
corn growing possessed merit as a preparation of the land for a crop 
of small grain. When these two factors are combined in one crop 
they make its growth of double importance. Corn is the only crop 
at present available that offers this advantage which at the same 
time lends itself to large acreage and a general farming system. 
The grain sorghums fit equally well into a farming system that 
includes the production of live stock, but they are not adapted to the 
whole of the Great Plains, and furthermore have not in general 
shown an effect so beneficial as corn on the following crop. 
Potatoes have approximately the same effect as corn upon most 
crops that may follow them, but the potato crop does not lend itself 
so well to growth on a large acreage. 
The effect of the growth and clean cultivation of corn as compared 
with summer tillage and various other methods of preparation has 
been shown in bulletins simultaneously written on the growth of 
spring wheat, oats, and barley in the Great Plains area. In these 
publications it has been shown that the crops following corn have 
consistently given high yields as compared with other methods of 
preparing a seed bed for these crops. In many cases the highest 
yields of small grain have been obtained on disked corn ground. In 
many other cases where disked corn ground has not been productive 
of the highest yields, it has so nearly approached them that when the 
cost of preparation is considered it is found to be productive of the 
greatest profit. This has attached so much importance to the corn 
crop that it appears to be desirable to present the actual data on the . 
production of corn in the different years at the different stations and 
under different methods of cultivation and preparation for the crop. 
TYTiile corn in most cases has been grown in preparing for other 
crops and in cropping systems primarily arranged for the growth 
of other crops, the necessity for studying methods of producing 
the crop itself has not been overlooked. In general terms, corn 
has been grown by different methods under a system of continuous 
cropping. It has been grown at some stations in 2-year rotations 
of alternate corn and wheat and corn and oats. It has been grown 
in 3-year rotations where the other two crops were wheat and oats 
or barley and oats. It has been grown in 4-year rotations with 
small grams and fallow or the use of green manure. It has also 
been raised as the second crop from the sod in sod rotations. In 
some of the rotations manure has been applied before plowing the 
ground for corn. 
Some of the rotations are calculated to conserve or increase the 
fertility of the soil, while others may perhaps deplete it. In the 
present stage of the. work the effects of the rotations as units are 
greatly overshadowed by the effects of the cropping and cultivation 
for a single year. This is due to the fact that the controlling factors 
