DEPTH OF CULTIVATION 



183 



an almost impervious sub-surface strata. As more humus is intro- 

 duced into these soils, the surface cultivator may come into more 

 practical usefulness for laying by corn. 



From the results of an experiment conducted in Indiana for five 

 years, the average yield of corn was 42.3 bushels per acre for the shal- 

 lovir cultivation, (1 to 3 inches) and 37.9 bushels where cultivated four 

 inches deep. 



This experiment extended over a period of eight years with the 

 one, two and three-inch cultivations, and five years with the four- 

 inch cultivation. It will be seen that there was a decrease in the yield 

 when the cultivation exceeded the depth of three inches. This exper- 

 iment has been corroborated by the Iowa Experiment Station and in 

 some parts of this state by farmers who have paid special attention 

 to this investigation. 



A similar experiment was conducted at the Ohio Station* and the 

 results of a ten-year test showed an average yield of 56.4 bushels per 

 acre and 2661 pounds of stover from deep cultivation, as compared 

 with 60.4 bushels of grain and 2874 pounds of stover per acre from 

 the shallow cultivation. The double shovel was used in the deep cul- 

 tivation, and the spring tooth cultivator in the shallow cultivation. 



SURFACE CULTIVATOR 

 These shovels are made to pulverize the surface rather than stir to any considerable depth 



'Ohio Bulletin No. 282. 



