ROTATION AND CULTURAL METHODS AT EDGELEY, N". DAK. 17 



SOD CROPS. 



In humid sections sod-forming crops occupy an important place 

 in crop rotations. Three such crops were incorporated in the ex- 

 periments at Edgeley. These are brome-grass, alfalfa, and red 

 clover. Brome-grass is included in two rotations and alfalfa and 

 red clover in one each. The several rotations are all similar in that 

 the other crops are oats on sod, corn on fall-plowed oat stubble, and 

 wheat on disked corn ground. The two brome-grass rotations differ 

 from each other in only one respect. No. 12 is lengthened one year 

 over No. 10 by introducing a crop of flax on the brome-grass sod and 

 raising the oats on fall-plowed flax stubble. 



In the brome-grass rotations the brome-grass is seeded with the 

 wheat. Both the alfalfa and the clover are spring seeded without a 

 nurse crop on fall plowing. In the rotations containing these crops 

 there is consequently one year in which there is no production. 

 This loss of the use of the land is avoided in the brome-grass rota- 

 tions, which produce a crop each year. The brome-grass stands two 

 years, the alfalfa two years in addition to the seeding year, and the 

 red clover one year in addition to the seeding year. The experi- 

 ments were not intended to study brome-grass or alfalfa to deter- 

 mine how long they would remain productive. Neither was the 

 length of the rotations fixed by a consideration of what might be the 

 most profitable practice. They were purposely made short to meet 

 the exigencies of experimentation and to determine as quickly as pos- 

 sible the effect of seeding and breaking up these crops. It was thought 

 that a full sod would be formed and the effect on succeeding crops 

 determined as well by standing for two years as for longer periods. 



No. 10 is a 5-year rotation of oats, corn, wheat with brome-grass 

 seed, and two years of brome-grass meadow. The oats are seeded on 

 brome-grass sod broken in midsummer of the preceding season. The 

 average date of harvesting the hay crop is July 12, or about three 

 weeks before grain harvest. The instructions are to break the sod 

 as early as convenient and possible after the hay crop for the. year 

 has been secured. Generally the sod has been backset late in the fall. 

 The average yield of oats for the 12-year period from 1908 to 1919 

 has been 27.7 bushels. This yield might be compared with an 

 average yield of 30.5 bushels per acre of oats following wheat in three 

 3-year rotations of corn, wheat, and oats. The yield of corn on 

 spring plowing following the oats has been slightly more than 

 when following oats in 4-year rotations containing fallow and green 

 manures and slightly less than following oats in 3-year rotations of 

 corn, wheat, and oats. It can not be stated positively that the intro- 

 duction of brome-grass sod into the rotation has had a significant 

 effect on the yield of corn grown the second year after breaking the 

 sod. The yield of wheat following the corn has been practically the 

 same as that of wheat following corn in 3-year and 4-year rotations. 



