352 



SOIL PHYSICS AND MANAGEMENT 



average. It is without doubt true that if the ground is plowed to a 

 depth of six or seven inches, and a good seed bed produced, there 

 is very little necessity for cultivation of corn on silt loams and 

 sandy loams to conserve moisture. It will be seen from the following 

 table that during the dry years of 1911, 1913, and 1914 the yield of 

 corn on the uncultivated plots was 5 to 10 bushels more than on 

 the corresponding cultivated ones. The mulch should have had its 

 greatest effect during these seasons if it was of much use in con- 

 serving moisture for the crop. 



Results of Cultivation of Corn 3 Each is an Average of Two Plots (Bushels 



Per Acre) 



* Based on all comparable yields, 

 t Five-year average, 

 j Ten-year average. 

 8 Eight-year average. 



The cultivation was done so as to produce a mulch from 2y 2 to 

 3y 2 inches in depth. (See Figs. 170 and 171.) During the years 

 mentioned the mulch was so dry and loose that the roots of the 

 corn did not penetrate it, so that if it had any value at all it was in 

 conserving moisture. The corn roots generally develop most abun- 

 dantly in the plowed soil. By cultivating three inches deep the crop 

 was enabled to use only one-half of the plowed soil, and there was 

 no doubt that the stirred soil was worth more to the crop for the 



