22 



BULUETIX 1094, r. S. DEPARTME3!fT OF AGRICTILTTJRE. 



thin stand and winterkilling, and five sown in disked stubble averaged 

 3.9 busbels per acre. In 1918 three plowed plats averaged 15.8 bushels 

 and three not plowed 24.7 bushels. In 1919 three plowed plats 

 averaged 19 bushels and three unplowed 22.2 bushels. In 1920 four 

 plowed plats averaged 22.6 bushels and two unplowed 25.8 bushels. 

 In four years the total gain from not plowing was 19.2 bushels, an 

 average gain of 4.8 bushels per year. In this group of plats, as in 

 rotation No. 591, which has not been plowed since 1912, there is no 

 evidence of deterioration from the continued omission of plowing. 



Table 9. — Yields ofv:heat on plaits continuov^ly cropped to vjJieat hut plovjed at different 

 intervals at the Fort Hays branch station for the 5-year period from 1916 to 

 1920, inclusive. 



[Yields following plowing shown by boldface type.] 





Year. 



Yields per acre (bushels). 





Plat A. 



PlatB. 



Plate. 



PlatD. 





Average. 



Increase 





PlatE. 



Plat P. 



Plowed 

 plats. 



Un- 

 plowed 

 plats. 



on un- 

 plowed 

 plats. 



1916. 





33.8 

 



10.8 

 15.8 



17.5 



39.8 

 2.6 

 16.0 

 20.5 

 21.1 



35.2 

 3.8 

 23.8 

 21.8 



21.8 



37.4 

 4.9 

 26.3 

 22.3 

 23.4 



35.9 

 2.8 

 24.0 

 23.8 

 29.8 



38.8 

 5.6 

 20.5 

 19.5 

 28.5 









1917. 









15.8 

 19.0 

 22.6 



3.9 

 24.7 

 22.2 

 25.8 



3.9 



1918. 





8.9 



1919. 





3.2 



1920. 





3.2 





Average, 1917 to 1920. . 







11.0 



15.1 



17.8 



19.2 



20.1 



18.5 



14.4 



19.2 



4.8 



Near these plats in the field are two other rotations that were 

 started in time to be productive of evidence on the same subject 

 in 1919 and 1920. Rotation No. 568 is fallow, winter wheat on 

 faUow, and winter wheat sown in stubble. Rotation No. 580 is the 

 same thing lengthened one year by early plowing the last wheat 

 stubble and raising a third crop of wheat before fallowing. In 1919 

 the stubbled crop was heavier than either that fallowed or plowed. 

 In 1920 the fallowed was heavier than the stubbled, and the stubbled 

 heavier than the plowed. As has been noted before, 1919 was dis- 

 tinctly ufifavorable to methods that prompted a rank growth. In 

 1920 there was a similar tendency, but it did not go far enough to 

 overcome entirely the initial advantage enjoyed by such methods 

 as fallow.^ 



The somewhat anomalous condition is presented of early plowing 

 or cultivation jdelding heavier than late plowing, but no cultivation 

 at all sometimes yielding heavier than either and averaging nearly 

 as much as the best methods of early cultivation. The first is suscep- 



8 In 1921 the yield of the continuously stubbled plat known as rotation No. 591 feU to about one-half 

 that of early plowing, but was stiU above that of late plowing. In the other experiments described, wheat 

 sown in disked stubble on which plowing had been deferred for a lesser number of years maintained yields 

 as high as on early plowing, or even higher. 



