24 CULTIVATION METHODS AND ROTATIONS FOE GREAT PLAINS. 



These rotations were not planned nor are they here presented as 

 the best rotations for the Great Plains area. They are seriously 

 defective in that they make no provision for maintaining or restoring 

 the organic matter to the soil. They were established for the pur- 

 pose of studying the effects of crop sequence, or the effect that one 

 crop has upon the crops following it, and the relative merits of fall 

 and spring plowing. For these purposes these simple rotations have 

 some marked advantages over longer and better rotations. This 

 phase of the experiments will be but very briefly mentioned at this 

 time, although it is believed that the thoughtful reader may find 

 some very interesting, although possibly not conclusive, evidence on 

 these subjects by a careful study of these tables. This subject will 

 be more fully treated in some future publication. The purpose of 

 introducing these figures at this time is to show that even these 

 defective 3-year rotations have given better net results than either 

 the continuous cropping or alternate cropping and summer tillage 

 described in the foregoing pages. By " better net results" is meant 

 that at nearly all stations the yields have been better for all three 

 crops — wheat, oats, and barley — where the rotation of crops has been 

 practiced than where the same crop has been grown continuously on 

 the same ground. This statement is equally true concerning both 

 ordinary methods and moisture-conservation methods of continuous 

 cropping. The labor and expense involved in raising crops under a 

 system of rotation are not materially greater than where continuous 

 cropping by ordinary methods is practiced. The labor and expense 

 of raising crops under moisture-conservation methods of continuous 

 cropping are materially greater than under a system of crop rotation, 

 as these two systems have been practiced in these experiments. 



Where but one crop is raised in two years, as in the case of alter- 

 nate cropping and summer tillage, the labor and expense per crop 

 are nearly or quite double that of either rotation or continuous crop- 

 ping by ordinary methods. In order, then, to make the net results 

 as favorable under alternate cropping as under either continuous 

 cropping or crop rotation, the yields should be nearly double. Sum- 

 mer tillage has nearly always increased the yields, but it has seldom 

 doubled them. In only a few instances has this increase been suffi- 

 cient to pay the bare expenses of the additional labor involved. Crop 

 rotation has therefore given better net returns than either alternate 

 cropping and summer tillage or continuous cropping by either ordi- 

 nary methods or moisture-conservation methods, as is shown by 

 Tables XXII and XXIII. 



A COMMON BASIS OF COMPARISON. 



In order to answer many of the important questions concerning 

 the relation and adaptability of rotations, it is apparent that we 

 must have some common basis of comparison for the several crops 



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