LESSONS FROM EXPERIENCE 317 



likely to winter in good shape with a liberal aftermath. 

 After the rotation is in full swing there will be one field 

 in corn or other cultivated crop, one fiield in small grain 

 and one field in legume, either sweet clover or alfalfa. 

 Variations in this plan of rotation are easily made and 

 work out very nicely. In fact the rotation is so adapt- 

 able that it can be made to fit almost any requirement. 

 It can be changed to a four-course rotation by growing 

 two crops of corn in sucession, followed by the grain and 

 sweet clover or to a five-course rotation by growing corn 

 in one field for silage, following it with winter rye, fol- 

 lowing the rye with corn for grain and the corn in turn 

 with spring grain and sweet clover or alfalfa. The prin- 

 ciple involved in sucessful crop rotation in South Dakota 

 consists in providing for a cultivated crop preceding the 

 grain crop in order to conserve moisture and render the 

 seed bed firm and in good tilth for the seeding of the 

 grain and the hay crop. Yields in favorable seasons are 

 often doubled by this practice and in unfavorable seasons 

 yields are secured that are very satisfactory while the 

 crop on land put into grain continuously may prove a 

 total failure. 



262. Drought-Resistant Crops. — In the early years of 

 South Dakota's development great difficulty was experi- 

 enced because the crops which the settlers attempted to 

 grow were not of the proper variety. Through the efforts 

 of tlie United States Department of Agriculture and the 

 State College of Agriculture crops have been introduced 

 from south-central Russia and other countries where con- 

 ditions are somewhat similar and thoroughly tested in 

 comparison with varieties from other sources, until the 

 ones which were best for South Dakota conditions were 

 determined. After introduction and testing, these var- 



