46 CIRCULAR 421, U. S. DEPARTMENT OF AGRICULTURE 



Crop -production work was conducted along three principal lines: 

 (1) Crop rotations, (2) fields, and (3) variety tests. 



Average yields of all crops grown in the rotations during the 20- 

 year period give a fair index of the yields that may be expected under 

 dry-land conditions in the section. 



Methods of cultivation played a relatively unimportant role in de- 

 termining crop yields. The preceding crop rather than the method 

 of land preparation seemed to determine the yield, so long as the 

 method of cultivation did not encourage weed growth or delay 

 seeding. 



Difference in crop sequence resulted in major differences in yield. 

 Small grains grown after a cultivated crop produced yields approxi- 

 mately one-third higher than after small gram, and after fallow they 

 produced yields approximately two-thirds higher than after small 

 grain. Somewhat different responses were shown by the different 

 grain crops. 



The yields of cultivated crops were not appreciably higher when 

 grown after cultivated crops than after small grains. Cultivated 

 crops showed less response to fallow than small grain crops. 



The effect of a cultivated crop in a rotation was evident the second 

 year following. Yields of grain after grain in 3-year rotations con- 

 taining a cultivated crop were approximately 20 percent higher than 

 where grain was grown continuously. 



Yields of grains following manured fallow were somewhat higher 

 than following unmanured fallow. This difference was greatest in 

 the most productive years. When yields were low, the yields fol- 

 lowing manured fallow were as low as or lower than yields follow- 

 ing unmanured fallow. No cumulative benefit from the use of 

 manure was evident during the life of the experiments. 



Small-grain crops on green-manured land produced lower yields 

 than on land that was bare fallowed. No cumulative benefit from 

 plowing under green-manure crops was shown. 



Crops were grown on fields for the purpose of producing feeds. 

 Average yields from fields compared favorably with average yields 

 from plots. Besults from one field demonstrated that corn land 

 and sorgo land are practically equal as preparations for small grains. 

 Feed-crop rotations showed that dependable production of feed 

 crops can be obtained over a series of years. 



Variety tests with wheat demonstrated that both Ceres and Keli- 

 ance were more productive than Marquis during the 7-year period 

 1926-32. Some varieties grown only after 1929 showed promise and 

 should be tried further. Brunker oats were the most productive 

 variety tested. Gopher oats were better than Sixty-Day but not so 

 productive as Brunker. White Smyrna barley and Ace, a selection 

 of White Smyrna, were outstandingly more productive than other 

 varieties tested. Early varieties of both oats and barley were more 

 productive than midseason or late varieties. Variations in yield 

 between varieties were extreme, and sometimes accounted for greater 

 differences in yield than resulted from major differences in crop 

 sequence. 



Kainbow Flint corn produced higher silage yields than any other 

 corn variety grown. Yields of Dakota Amber sorgo were as high 

 as those of Rainbow Flint in terms of dry matter per acre. Little 



