150 ILLINOIS STATE ACADEMY OF SCIENCE 



Crop yield has also been taken as a criterion of effect and 

 here also no consistent or significant difference in the yield 

 of the various plots has occurred. 



This information, while entirely negative, is of consider- 

 able value as a guide in planning future work which may 

 lead to the discovery of a method of underdraining this ex- 

 tensive area. It also furnishes the Experiment Station 

 with a sound basis upon which to base advice to farmers 

 of this region regarding the advisability of purchasing sub- 

 soil or deep tillage plows, or of using dynamite in an effort 

 to shatter and render more pervious the tight clay subsoil. 

 These investigations, together with similar investigations 

 which have been carried on at other stations, seem to point 

 without question to the conclusion that the remedy for this 

 unfavorable subsoil condition is not to be found in deep 

 tillage or in the use of dynamite. Further investigation 

 must determine whether a practicable remedy can be found. 

 The problem is of such far-reaching economic significance 

 that upon its successful solution depends, to a large extent, 

 the material welfare of an extensive area in Illinois. 



The possibilities of attack have not been exhausted and 

 valuable information has been secured in the work thus far 

 attempted. Future efforts, it seems, must first be directed 

 toward a study of the exact nature and behavior of this 

 plastic material, and then with this knowledge as a basis 

 we will be in a position to attack the problem in the field 

 more intelligently. 



Discussion of Paper on "The Agricultural Significance 

 of the Tight Clay Subsoil." 



Mr. Haas asked whether the failure to have any effect 

 through deep plowing, subsoiling or dynamiting might not 

 be due to lack of underdrainage or tiling. In his own ex- 

 perience on a small scale in northern Ohio through dyna- 

 miting, from appearances, only, there seem to be a distinct 

 gain in "drawing" power of tile as well as the growth of 

 plants. In reply to the question whether the negative 

 results obtained might not be due to the plowing down of 

 the soil rich in humus and bringing to the surface of large 

 quantities of gumbo, Mr. Smith replied that the color of 



