244 ILLINOIS STATE ACADEMY OF SCIENCE 



strate that the corn yields may be increased greatly by 

 the addition of nitrogenous organic matter and limestone. 

 The following table shows the corn yields obtained on 

 three experiment fields located in southern Illinois. 

 These fields are on a soil type known as Gray Silt Loam 

 On Tight Clay, and this type predominates over a large 

 area of the southern part of the state. 



CORN YIELDS 8 YEAR AVERAGE (1915-22) BUSHELS PER ACRE. 



Soil treatment Ewing Oblong Toledo Average 



Crop residues and lime- 

 stone—sweet clover. 31.7 36.8 27.7 32.0 



Crop residues only 12.9 26.6 17.3 18.9 



Gain for lime — sweet 



clover 18.8 10.2 10.4 13.1 



The average gain for the lime-sweet clover treatment 

 on these three fields is 13.1 bushels of corn per acre. This 

 type of soil is much less fertile than that of the corn belt, 

 as indicated by the corn yields, but these experiments 

 show that the productiveness of this soil may in some 

 cases be almost doubled by the application of the soil 

 treatment indicated. 



The following table shows the corn yields obtained 

 from three experiment fields located in the extreme part 

 of southern Illinois. These fields are on a type of soil 

 known as Yellow Gray Silt Loam. This land was former- 

 ly timbered, and is the predominating type over a large 

 area of the southern part of the state. 



CORN YIELDS 8 YEAR AVERAGE (1915-22) BUSHELS PER ACRE. 

 Soil treatment Raleigh Unionville Enfield Average 



The average gain for the lime-sweet clover treatment 

 on these three fields is 15.2 bushels of corn per acre. This 

 is the largest increase on any of the types of soil men- 

 tioned, and indicates to what extent corn yields may be 

 increased on these less fertile soils of southern Illinois. 



The corn yields on the twelve experiment fields named 

 show an increase of 11.3 bushels per acre as an average 

 of the past eight years. It would seem from the distri- 



