LEGUMES AND GRASSES 



in Dryland Cropping Systems 

 in the Northern and Central Great Plains 



A Review of the Literature 



By Paul L. Brown, soil scientist, Soil and Water Conservation Research Division, Agriculture 



Research Service 



The purpose of this publication is 

 to review the literature and deter- 

 mine the value of legumes and 

 grasses as soil-conserving and soil- 

 improving crops in the northern and 

 central Great Plains. 



This publication summarizes the 

 following experimental data: (1) 

 Comparison of crop yields in rota- 

 tions with and without legumes and 

 grasses; (2) comparison of legumes 



versus inorganic sources of nitro- 

 gen; (3) soil-moisture use by leg- 

 umes and grasses; and (4) chemical 

 and physical effects of legumes and 

 grasses on soils. The term "grass," 

 as used in this publication, excludes 

 cereal crops. The terms "carbon" 

 and "organic carbon" have been 

 used as the authors in the source 

 materials used them. 



GEOGRAPHICAL AREA 



The northern and central Great 

 Plains includes most of North 

 Dakota and South Dakota, Ne- 

 braska, Kansas, eastern Colorado, 

 eastern Wyoming, and eastern 

 Montana. It also includes parts 

 of Alberta, Saskatchewan, and 

 Manitoba (7). 1 Figure 1 delineates 



the area under discussion. The 

 experiment stations at Fargo, N. 

 Dak., Lincoln, Nebr., and Man- 

 hattan, Kans., are just east of the 

 Great Plains, but pertinent experi- 

 mental data from these locations 

 were included to show State and 

 regionwide relationships. 



REVIEW OF UNITED STATES SOIL-MANAGEMENT 



PROBLEMS 



oeneral 



Dryfarming problems in the 

 northern and centra] Great Plains 

 have been discussed frequently in 

 the literature of the 20th century. 

 The advantages and disadvantages 

 of the use of legumes and grasses 

 as soil-improving and soil-conserv- 

 ing crops have been reported. 



In 1917, Pieters (66) reviewed all 

 American experiment station liter- 



1 Italic numbers in parentheses refer 

 to Literature Cited, p. 60. 



ature on the subject of green 

 manuring. This review was to de- 

 termine the value of legumes as 

 measured by yields of succeeding 

 crops. He reported data from 28 

 States and Canada. His findings 

 show that the value of legumes 

 as green manures decreased from 

 the Southeastern to Northwestern 

 United States. In the Dakotas and 

 Canadian Northwest, the use of legu- 

 minous green-manure crops was not 

 profitable. In this area, green- 

 manure crops used the moisture 

 needed for the main crop. 



