1242 



EARLE V. HARDENBURG 



TABLE 73. RELATION OP DEPTH OF PLANTING TO YIELD ON 300 FRANKLIN AND CLINTON 



COUNTY FARMS IN 1913 



The evidence in table 73 indicates that the yields began to decrease from 

 planting at depths greater than 4 inches. Evidently, in soils as light as 

 those of this locality, planting at greater depths than the average of 2.6 

 inches for 1913 may be recommended. 



Depth of planting is a factor which would require controlled experi- 

 ments covering several years in order to determine the most effective 

 depth for any given region. The evidence of a single year from the sur- 

 veyed regions indicates that in the heavier soils it is safe to plant shallower, 

 and in the lighter soils deeper, than the average depth for 1912 and 1913. 



DEPTH OF CULTIVATION 



The term cultivation has been used so promiscuously in agricultural 

 literature that it seems well to define its limitations as used in this study 

 before entering on any discussion of its influence on the yield of potatoes. 

 Cultivation has for its primary objects, weed control and moisture con- 

 servation. Any operation on the crop after it is up, which stirs the soil 

 for either or both of these purposes, is therefore included within the meaning 

 of the term as here used. Such operations as using the weeder, pulling 

 weeds, hoeing, and hilling or ridging the crop, are comprehended by the 

 term. This will account for the great frequency of cultivation noted 

 in the studies of the influence of this factor on yield. 



Harwood (1893) reported the results of forty-four tests on the influence 

 of depth, of cultivation on yield. Considering 1.5 inches as shallow and 

 5 inches as deep culture, forty of the forty-four tests gave total and 

 marketable yields favoring deep culture. As a rule, the greatest yield of 

 small and sunburned tubers was obtained from shallow culture. Schweit- 

 zer (1896), in a one-year test on potatoes planted 4 inches deep, compared 

 deep and shallow tillage. Altho his yields were almost equal, he obtained 



