232 EXPERIMENT STATION RECORD. 



and North Platte, Nebr. ; 2 at Amarillo, Tex., Dickinson, N. Dak., and Higlimore, 

 S. Dak.; and 1 at Judith Basin, Mont., Belle Fourche, S. Dak., Akron, Colo., 

 Dalhart, Tex., and Hays and Garden City, Kans. The author defines the terms, 

 "ordinary methods," "conservation methods," and "alternate summer tillage" 

 as used in this bulletin. 



Experiments with wheat, oats, and barley were conducted at each station, 

 the grain being grown (a) continuously by ordinary cultural methods on 

 spring-plowed land; (b) continuously by moisture conservation methods on 

 fall-plowed land; (c) alternating with summer tillage; and (d) with summer 

 tillage alternating with grain. The wheat yields by ordinary, conservation, 

 and summer tillage methods were 17.4, 16.5, and 22.5 bu. per acre, respectively. 

 The same methods yielded respectively 30.2, 30.5, and 44.1 bu. per acre with oats, 

 and 21.1, 22.9, and 30.7 bu. per acre with barley. These averages were for all 

 stations at which the tests were conducted. 



At each of the 11 stations, 5 identical 3-year rotations were instituted with 

 wheat, oats, and corn, in 2 rotations barley was substituted for wheat, and in 2 

 others summer tillage displaced corn. " Rotations are so planned as to give an 

 opportunity to compare the several rotations considered as units and also to 

 compare the several crops grown in different rotations under systems of soil 

 preparation and following different crops. As each rotation is represented 

 by three plats, each of the crops entering into the rotation is represented every 

 year." Wheat, oats, and barley in continuous cropping by ordinary methods 

 yielded on the North and South Dakota, Nebraska, and Kansas plats during 

 1900-1909 17.4, 30.2, and 21.1 bu. per acre respectively, while in 3-year rotation 

 they yielded 19.8, 36.3, and 24.3 bu. per acre respectively. Tables present the 

 yields of grain in bushels per acre and their farm value per acre in each of 

 the rotations in the 19 tests conducted during 1906-1909. Tables show the aver- 

 age farm value per acre yielded by each of the nine 3-year rotations and the 

 gain or loss of each rotation for each test as compared with continuous crop- 

 ping by ordinary methods. 



Disked corn stubble proved superior to summer tillage preceding spring wheat 

 and oats, giving an average net gain per acre of $4.08. Omitting the value of 

 the corn from consideration the average gain in favor of summer tillage was 

 ?1.04, but even then disked corn stubble had the advantage in 7 of the 19 tests. 

 Tests of fall and spring plowing gave negligible differences in results. The 

 choice depends upon local conditions of soil and climate. Wheat, oats, corn 

 proved a better sequence for spring plowing than oats, wheat, corn at most of 

 the stations. 



The author enumerates the experimental difficulties in work on rotations for 

 the conservation of organic matter in the soil, but in the light of work already 

 done, discusses the growing of corn, brome-grass, and small grains, and recom- 

 mends a corn, wheat, brome-grass, brome-grasr, small grain, and other rotations 

 as adapted to the conservation of organic matter. 



The author regards his conclusions as tentative and subject to modification by 

 future results, but indicates that alternate cropping and summer tillage have 

 not proved profitable and that certain 3-year rotations have proved more profit- 

 able than continuous cropping or alternate cropping. Corn on spring or fall 

 plowing, followed by wheat or barley on disked corn stubble, and then by oats 

 on early fall plowing, has given the best average results. Winter rye has so 

 far given better results for green manuring than Canada field peas and sweet 

 clo^'er (Melilotus alba), perhaps because it can be plowed under before the end 

 of the June rains. Flax may be grown on brome-grass sod as a catch crop after 

 the hay is harvested. Winter wheat possesses several important advantages 

 over spring wheat, fits in well in any rotation adapted to the Great Plains, and 



