14 CIRCULAR NO. 114, BUREAU OF PLANT INDUSTRY. 



Table IV shows that in only a very few instances has the percent- 

 age of moisture in subsoiled land been greater than that in land not 

 subsoiled, while in most instances it has been somewhat less. The 

 means were obtained, not from the monthly averages, but by con- 

 sidering the entire number of samples taken during the sampling 

 period. In both pairs of plats the averages indicate a larger per- 

 centage of soil moisture in land not subsoiled than in the subsoiled 

 land. 



CONCLUSIONS. 



(1) Subsoiling is an expensive practice and so adds to the cost of 

 preparation for a crop that unless materially increased yields result 

 it can not be profitably adopted as a regular farm practice. 



(2) Subsoiling has been tested at the San Antonio Experiment 

 Farm for three years in rotation experiments with corn, cotton, and 

 oats for hay and for grain. 



(3) The yields of corn, cotton, and oats for hay and for grain have 

 been either slightly increased or slightly decreased on subsoiled land. 

 In no instance has the difference been significant. 



(4) The depressing residual effect of subsoiling on the yields of 

 corn and cotton was most marked when the crop was planted from 

 1 to 8 months after subsoiling; 15 months after subsoiling but little 

 depressing effect was noted. 



(5) In the soil-moisture studies so far made at San Antonio it has 

 been found that subsoiling has not increased the moisture content of 

 the soil. 



((>) The results of these tests indicate that since neither the 

 moisture content of the soil nor the yields of corn, cotton, and oats 

 are increased by subsoiling, the practice is not advisable in connec- 

 tion with the crops mentioned in the San Antonio region of Texas. 

 [Cir. 114] 



