60 MISCELLANEOUS PUBLICATION 952, U.S. DEPT. OF AGRICULTURE 



straw residues decrease erosion by 

 increasing nonerodible aggregates 

 in soil. After residues are decom- 

 posed, there is evidence that wind 

 erosion may be aggravated, because 

 soil structure breaks down into 

 wind-erodible aggregates. 



Where present cropping systems 

 result in greater than allowable 

 soil losses, 9 a change in cropping 

 system is needed. Excessive ero- 

 sion eventually decreases yields. 

 Incorporating legumes and grasses 

 in the cropping system is an effec- 

 tive way to reduce soil losses. 

 Legumes and grasses are well 

 adapted to subhumid class III 

 lands, 10 such as in northeastern 



9 KLINGEBIEL, A. A. SOIL FACTOR 

 AND SOIL LOSS TOLERANCE. In Soil LOSS 



Prediction — North Dakota, South Da- 

 kota, Nebraska, and Kansas., pp. 18-19. 

 Soil Conserv. Serv. (Report presented at 

 Soil-Loss Prediction Workshop, Lin- 

 coln, Nebr., Mav 8-9, 1961.) 



10 See footnote 8, p. 58. 



Nebraska, because of continuous 

 need for wind and water-erosion 

 protection. On such lands, com- 

 mercial nitrogen to supplement 

 legume nitrogen may be necessary 

 for optimum crop production. 



Legumes and grasses are valuable 

 crops in themselves. They are an 

 essential part of any livestock 

 enterprise. 



This review brings out the fact 

 that not enough research work has 

 been done to assess completely the 

 effects of legumes and grasses under 

 all soil and climatic conditions of the 

 northern and central Great Plains. 

 Historically, legumes- and grass- 

 rotation experiments were mostly 

 located on favorable sites. Ero- 

 sion effects cannot be studied ade- 

 quately under these conditions. 

 Even now (1963), few rotation 

 experiments are designed to study 

 the longtime effects of soil erosion 



LITERATURE CITED 



(1) Army, T. J., and Hide, J. C. 



1959. EFFECTS OF GREEN MANURE CROPS ON DRYLAND WHEAT PRODUCTION 

 IN THE GREAT PLAINS OF MONTANA. Agron. Jour. 51 1 196-198. 



(2) Bell, M. A. 



1937. THE EFFECT OF TILLAGE METHODS, CROP SEQUENCE, AND DATE OF 

 SEEDING UPON THE YIELD AND QUALITY OF CEREALS AND OTHER 

 CROPS GROWN UNDER DRYLAND CONDITIONS IN NORTH-CENTRAL 



Montana. Mont. Agr. Expt. Sta. Bui. 336, 100 pp. 



(3) Brandon, J. F., and Mathews, 0. R. 



1944. DRYLAND ROTATIONS AND TILLAGE EXPERIMENTS AT THE AKRON 



(Colorado) field station. U.S. Dept. Agr. Cir. 700, 53 pp. 



(4) Bray, J. O., and Schnittker, J. A. 



1956. legumes or commercial fertilizers? Kans. Agr. Expt. Sta. Bui. 

 384, 16 pp. 



(5) Canada Department of Agriculture. 



1956. soil fertility. Canada Expt. Farm Soil Res. Lab. Swift Current 

 (Sask.) Prog. Rpt. 1948-54: 27-43. 

 (6) 



1959. research highlights [for] 1958. Canada Expt. Farm Lethbridge 

 (Alberta) Lith. Mimeo. 10: 6-8. 



(7) Canada Department of Mines and Technical Surveys. 



1957. soil regions 35. Atlas of Canada. 



(8) Carpenter, R. W. 



1948. EFFECT OF ORGANIC AMENDMENTS ON CROP YIELDS AT MANDAN, 



north Dakota. N. Dak. Expt. Sta. Bimo. Bui. 10, pp. 87-89. 



(9) Chepil, W. S. 



1955. FACTORS THAT INFLUENCE CLOD STRUCTURE AND ERODIBILITY OF SOU 

 BY WIND: V. ORGANIC MATTER AT VARIOUS STAGES OF DECOMPOSITION. 



Soil Sci. 80: 413-421. 



