ROTATION AND CULTURAL METHODS AT EDGELEY, N". DAK. 19 



inferiority may be due to a difference in soil. When the results are 

 separated into 4-year periods and studied it is seen, however, that 

 the brome-grass and alfalfa rotations have not been undergoing any 

 changes in their relative yielding powers. 



The manured rotation No. 71 adjoins rotation No. 42. The corn 

 following oats and the wheat on disked corn ground in this rotation 

 exceed in yield the corresponding crops in rotation No. 42. 



No crop is harvested the year the alfalfa is seeded. In 1909 and 

 again in 1918 the 1-year-old alfalfa winterkilled, while the new seed- 

 ing did not. In 1919 both plats winterkilled. Aside from these 

 failures there has been a crop each year. Three years it has amounted 

 to over 2 tons per acre, but the 12-year average yield from each plat 

 has been slightly in excess of 1 ton. Two crops have been cut in only 

 4 of the 12 years. In 1916 a third cutting was made on the older plat. 



It is fairly evident from these results that alfalfa in this section 

 must stand on its own merits as a crop, as its introduction into a rota- 

 tion decreases rather than increases the yields of following crops. 

 It appears that alfalfa fields should stand as long as they are satis- 

 factorily productive, rather than be broken up for the sake of ro- 

 tation. 



No. 11 is a 5-year rotation of oats, corn, wheat, and two years of 

 clover. One of the clover years is devoted to seeding down, and the 

 second is the crop year. After the crop is harvested the sod is fall 

 broken for oats. This rotation can be considered a failure, because 

 the red clover so frequently fails to survive the winter. It has been 

 a total failure in 5 out of 12 years and in 3 other years has produced 

 less than 1,000 pounds of hay per acre. Its 12-year average is 1,160 

 pounds, or only a little more than one-half that of alfalfa and less 

 than half that of brome-grass. The growth of clover has not in- 

 creased the yields of the other crops in the rotations. 



THE EFFECT OF THE SEASON ON YIELDS. 



In the preceding pages the effects of diverse cultural practices on 

 yields have been considered. It has been shown that in the average 

 of a series of years the differences resulting from wide divergence 

 of methods are very modest and in some cases not measurable by the 

 methods of investigation employed. When the results are studied in 

 detail year by year it is immediately seen that differences in yield 

 resulting from differences in soil treatment are of minor importance 

 when compared with the results of differences in seasons. 



The effect of seasonal conditions is shown clearly enough in the 

 average yields given in Table I, but it can be more effectively illus- 

 trated by the use of yields from individual plats representing widely 

 contrasting methods. It matters little which are selected for this pur- 

 pose, as all show much the same thing, as evidenced in the general 

 averages presented in Table I. Typical illustrations are offered in 

 rotations Nos. 5 and 8, which were described in considering the sub- 

 ject of small-grain stubble compared with fallow. Bare fallow might 



