8 BULLETIN 320, U. S. DEPARTMENT OF AGRICULTURE. 



YIELD FACTORS OTHER THAN TILLAGE. 



In such a study as this it is impossible to measure the effect of 

 tillage in terms of yield. This is true, for the reason that tillage is 

 only one of the many factors which have to do with yield, and while 

 yields are, for the most part, given in connection with these studies, 

 it is firmly believed that the yields are far more closely related to 

 the inherent fertility of the soil and to the general farm practices 

 than to tillage. 



The variations in yields, both regional and on individual farms 

 in a given region, show but scant correlation to variations in tillage 

 practice. There is, however, a striking correlation between yields 

 and type of farming. Yields in the main in the different regions are 

 in inverse ratio to the area of improved land which is in intertilled 

 crops. In some of the regions surveyed other factors enter which 

 affect crop yields, and in those regions this relation between the yield 

 of corn and the area of intertilled crops does not exist. Such con- 

 ditions are found in Scotland County, N. C, and Hartford County, 

 Conn., where large quantities of commercial fertilizer are used, and 

 in Augusta County, Va., and Bradford County, Pa., where the land 

 is rolling or rough and corn is grown mostly on the bottom lands 

 with hay and pasture on the hillsides. However, notwithstanding 

 these factors, when the regions included in this study are arranged 

 in order of rank in yield, the first 10 show but 29.5 per cent of 

 improved land in intertilled crops, with a yield of 45.4 bushels of 

 corn per acre, while the remainder show an average of 52 per cent 

 of the improved land intertilled, with a yield of only 27.4 bushels of 

 corn per acre-. Again, it is well known that in a large measure hay 

 and pasture enter into the rotation to supplement intertilled crops. 

 In other words, far more than for tillage, yields of corn tend to vary 

 directly with the extent to which crops adding organic matter to the 

 soil — hay and pasture crops — enter into the rotation. 



ECONOMIC FACTORS INFLUENCING TILLAGE. 



In Table I, as in all the general tables, the areas surveA'ed are 

 placed in the order of bushel yield of corn per acre, starting with 

 the area having the highest yield. The only direct bearing of Tables 

 II and III on tillage is in showing the acreage of cultivated land and 

 of intertilled crops per horse for the regions studied. The other mat- 

 ter presented, however, does have an important indirect bearing on 

 the subject of tillage, in that it gives the reader a general knowledge 

 of existing farm conditions. This information is necessary to a 

 proper interpretation of the purely tillage data presented in subse- 

 quent tables. 



