6 BULLETIN 218, U. S. DEPABTMENT OP AGBICULTTJBE. 



Summer tillage is of the intensive type. The land lies fallow for 

 a year. It is kept clear of weeds and as far as practicable a mulch 

 is maintained on it during the time between the harvest of the pre- 

 ceding crop and the seedhig of the oats. This involves a period in 

 some cases as long as 21 months. In some cases it is necessary to 

 plow the land more than once during this period, in order either to 

 maintain a surface receptive to water and that will resist blowing or 

 to prevent the growth of weeds. The long period of summer tillage, 

 together with the intensive methods practiced, have made this an 

 expensive system of production. Experiments are under way to 

 determine the most economical method of summer tilling. Indica- 

 tions are that a less intensive method than that practiced in the work 

 here reported will give practically as good returns. 



The yields given in these tables begin with the second year of crop 

 production at each station. The first year's crop is produced on 

 land uniform in its treatment. 



In cases where an entire crop has been lost by hail or other agency 

 that could not possibly be overcome by cultivation the years are not 

 considered in computing averages. Such failures must of course 

 enter into the final results of agricultural endeavor. They are, how- 

 ever, of such uncertain occurrence that the series of years here con- 

 sidered is too short to permit an attempt to establish their normal 

 frequency for any locality. This is in effect what would be done by 

 including them in averages. It is believed that less error is intro- 

 duced by recognizing their occurrence and excluding them from aver- 

 ages. When the loss of a crop is due to conditions that might pos- 

 sibly have been overcome by cultural practices a zero yield for that 

 year is included in the calculations. 



Embodying the basic data given in Tables II, III, and IV, the 

 second part of the table for each station has been compiled. In this 

 are brought together in summary form the yields detailed in the first 

 part of such table. The value of the average yields thus obtained is 

 calculated and given, together with a computation of the cost of pro- 

 duction. The last line of the table gives the profit or loss resulting 

 from the production of oats by the method stated. Loss is indicated 

 by the minus sign. In this second part of each table there are two 

 general headings : "Tillage treatment" and "Previous crop." Under 

 the first general heading the plats are grouped entirely by treatment 

 without considering the previous crop. Under the second heading 

 treatment is not considered, and the grouping is entirely governed by 

 the crop immediately preceding the oats. This really makes two 

 tables combined in one, with subdivisions common to both. 



Figure 2 shows a diagram of the dry-land rotation field at the 

 Belle Fourcho Field Station. This station being a representative 

 one will serve to illustrate the general scheme and plan of work. 



