LEGUMES AND GRASSES 



15 



more friable and worked into a 

 seedbed more readily. This physi- 

 cal effect disappeared almost com- 

 pletely after- about 4 years. Land 

 that had recently been in sweet- 

 clover was especially susceptible to 

 wind erosion. Sod crops left the 

 land exceedingly dry and often de- 

 creased the yields of succeeding 

 crops. When used in deferred ro- 

 tations with the land cultivated for 

 longer periods between sod crops, 

 yields of other crops were not re- 

 duced but were increased occa- 

 sionally in years of favorable pre- 

 cipitation. This was particularly 

 true in rotations with alfalfa. The 

 authors concluded that alfalfa and 

 grasses had a definite place on any 

 livestock farm but their place was 

 not in short rotations. When used, 

 it was recommended that alfalfa 

 and grasses be left in production 

 several years. 



In 1956, Puhr and Worzella (69) 

 outlined a recommended program 

 for management of South Dakota 

 soils. This included the use of 

 legume and grass rotations, with 

 phosphorus applied to the legumes, 

 nitrogen to the grasses, and nitro- 

 gen and phosphorus to small grains 

 and corn. 



West in and coworkers (82) re- 

 ported that water erosion was 

 serious on sloping lands in eastern 

 South Dakota. Erosion was best 

 controlled by increasing the per- 

 centage of legumes and grasses in 

 the cropping sequence. 



Summary 



Green manures were of little 

 benefit in western South Dakota. 



At Ardmore and Newell, brome- 

 grass and alfalfa depressed the 

 yields of crops that immediately 

 followed because of the dry condi- 

 tion in which they left the soil. 

 Grasses and legumes are valuable 

 crops on any livestock farm. They 

 should be grown for several years 

 rather than used in short rotations. 



711-108—64 3 



Sod crops had an observed bene- 

 ficial effect on Pierre clay for about 

 3 years after plowing. Land was 

 more friable and worked into a 

 seedbed more readily. Quantita- 

 tive measurements on physical im- 

 provement were not made. Re- 

 cently plowed sweetclover land was 

 observed to be especially susceptible 

 to wind erosion. 



Although experimental data were 

 limited, commercial nitrogen ap- 

 peared to be more efficient in crop 

 production than legume nitrogen in 

 the eastern part of South Dakota. 

 There were exceptions to the fore- 

 going statement, however. 



Legumes and grasses are an ef- 

 fective means of decreasing serious 

 water erosion on the sloping lands 

 of eastern South Dakota. 



Montana 

 Yields 



Green-manure experiments were 

 started at Havre, Mont., in 1917, 

 Moccasin, Mont., in 1909, and 

 Huntley, Mont., in 1913 (1, 2, 28). 

 Yields of several crops after green- 

 manure fallow, continuous crop- 

 ping, ordinary fallow, alfalfa, and 

 bromegrass are presented (table 

 10). Annual precipitation for 

 Havre, Moccasin, and Huntley av- 

 eraged 13.1, 14.0, and 13.4 inches, 

 respectively. 



In 1933, Hansen and coworkers 

 (28) reported on dryland crop yields 

 at Huntley Field Station for 1913- 

 30. Oat yields after green-manure 

 fallow were less than after ordinary 

 fallow. 



Seedbeds prepared by plowing 

 green-manure crops were invariably 

 rougher and more difficult to till 

 than those prepared by stubble 

 plowing in the spring for ordinary 

 fallow. Turning under sweetclover 

 and peas after the soil was dry 

 usually resulted in the seedbed 

 having large clods that were not 

 satisfactorily broken up by planting 



