346 THE SMALL GRAINS 



these experiments, spring (durum) wheat, oats, and barley 

 follow summer tillage, small-grain crops on both fall and 

 spring plowing, alfalfa, brome-grass, clover, corn, and 

 flax. In addition to these, rye, peas, and sweet clover are 

 sometimes used for green-manures as previously discussed 

 (370). The chief results obtained were as follows : 



(1) As already stated, the green-manure crops often 

 caused better yields of the following cereal crops than any 

 other soil treatment, but the cost was very great. (2) Al- 

 falfa, clover, or brome-grass sod turned under usually gave 

 indifferent or poor results even compared with cereal after 

 cereal. It should be noted that brome-grass appears 

 better than either of the others. (3) At all except 1 

 of the 7 northern stations where oats followed flax, the 

 yields were less than when oats followed other cereals. 



(4) Much the best yields of all the spring cereals at nearly 

 all the 14 stations were obtained on summer tillage. 



(5) The next best results were usually secured following 

 corn, the ground being disked before spring seeding. 



(6) The cost of summer tillage was so great compared with 

 the difference in yields between these 2 methods that 

 the profit from the cereal crop on disked corn ground is 

 considerably greater than that from any other method. 



(7) At the 2 stations, Hettinger, North Dakota, and Belle 

 Fourche, South Dakota, where oats and spring wheat 

 were on disked potato ground, the results were close to- 

 those obtained on disked corn ground, and better in one 

 case. (8) Oats did not do as well following sorghums as 

 following corn, though in one case, Hays, Kansas, the 

 yield was better after sorghums. 



As a general rule, "Seasonal conditions have produced 

 much wider variations in yields than have been produced 

 by differences in cultivation. Reducing the cost in pro- 



