14 CIRCULAR 421, U. S. DEPARTMENT OF AGRICULTURE 



The average yield of spring wheat after a cultivated crop was 38 

 percent higher than following a small-grain crop. This illustrates 

 the value of a cultivated crop in a rotation, above its value as a crop. 

 The yield of spring wheat averaged 59 percent higher on fallow than 

 it did following small ■ grains. The total production of a farm all 

 planted to small grain would be higher than that of the same farm if 

 half of it were planted to grain on fallow and half of it kept fallow. 

 The value of the fallow lies in the fact that the yield is better dis- 

 tributed between years, and that the distribution of labor would en- 

 able one man to handle a larger acreage of land with the same 

 equipment. 



The effectiveness of fallowing in overcoming drought is shown in 

 the yields by individual years. Not counting the 2 years when hail 

 totally destroyed crops, spring wheat on fallow produced 10 bushels 

 or more of grain per acre in all except 3 of the 18 years. During the 

 same period spring wheat after small grains produced less than 10 

 bushels per acre in 10 of the years. 



The average yield of winter wheat was 47 percent greater on corn 

 ground and 109 percent greater on summer fallow than it was fol- 

 lowing small grain. The apparently greater response of winter wheat 

 than spring wheat to corn ground and fallow was not due to larger 

 yields following those preparations but to lower yields following 

 small grain. 



The yield of oats following a cultivated crop exceeded that of oats 

 after small grains by 18 percent, and the yield on fallow exceeded 

 that following small grains by 51 percent. The response of oats to a 

 cultivated crop in the rotation was lower than that of spring wheat. 

 The response to fallow was nearly the same. The yield of barley 

 was 34 percent higher after a cultivated crop and 64 percent higher 

 after fallow than it was after small grains. 



The influence of the type of season on crop production is shown by 

 the production in different crop sequences during different periods 

 of years. For the purpose of study, the records were divided into 

 two 10-year periods. During the first period the increase for grain 

 on fallowed land above that of grain after grain was 45 percent for 

 spring wheat, 80 percent for winter wheat, 37 percent for oats, and 

 28 percent for barley. The increase during the second 10-year period 

 was 76 percent for spring wheat, 158 percent for winter wheat, 66 

 percent for oats, and 95 percent for barley. The percentage increase 

 due to fallow during the second 10-year period was double the in- 

 crease during the first 10-year period. This illustrates the value of 

 long-time determinations of results. Had the experiments been 

 conducted during only the first 10 years, the results would have been 

 relatively unfavorable to fallow. Records kept during only the sec- 

 ond 10 years would have given fallow an importance above its aver- 

 age deserts. Some of the increase during the last period may have 

 been due to better management of the fallow, but the major part 

 must be attributed to seasonal conditions. 



A comparison of crops in terms of pounds per acre instead of by 

 bushels is made in table 6. 



