12 



CIRCULAR NO. 120, BUREAU OF PLANT INDUSTRY. 



SUMMER FALLOWING. 



Three years' results have now been obtained from the tests in 

 summer fallowing land for corn, oats, and cotton. As in 1911, the 

 yields of crops on land summer-fallowed the previous season were 

 generally low, corn yielding at the rate of 24.7 bushels per acre, as 

 compared with the average of 34.1 bushels per acre on the 20 plats 

 in the rotation experiments. The corn on the summer-fallowed plat 

 yielded the lowest, save one, of any of the 26 plats. 



Cotton on summer-fallowed land yielded at the rate of 448 pounds 

 of seed cotton per acre, as compared with an average of 621.5 pounds 

 per acre on the 25 plats of cotton, giving the lowest yield of the 25 

 plats. 



Fig. i!. — Cotton on plat B 5-:!, land continuously cropped and not manured. This plat 

 has yielded an average of 307 pounds of seed cotton per acre during the past three 

 years. Compare with flsuro 4. (I'hotojiraphcd Juno 2G, lOli;. ) 



Oats for grain on a fallowed plat yielded at the rate of 37 bushels 

 per acre, the highest yield obtained from the 10 plats of oats. The 

 average yield from 10 plats Avas 26.75 bushels per acre. While the 

 oats on summer- fallowed land yielded somewhat higher than the 

 others, the increase was not sufficient to indicate that summer fallow- 

 ing is a desirable practice under the conditions at San Antonio, even 

 for oats. 



SUBSOILING. 



Subsoiling tests have been a rather important j)art of the rotation 

 and tillage experiments. The results have been sunnnarized and pub- 

 lished in Circular No. 114 of the Bureau of Plant Industry. 



[Cir. 120] 



