MISCELLANEOUS PUBLICATION 9 52, U.S. DEPT. OF AGRICULTURE 



the most active part of a grass crop 

 in the formation of soil aggregates. 

 This was demonstrated by the fact 

 that growing perennial grass was 

 much more effective than adding 

 grass clippings or hay to soil. 



In 1955, Duley and Coyle (17) 

 discussed dryfarming problems in 

 the United States. They stated 

 that the use of green manures was 

 not effective in improving growth 

 of the succeeding crops. They 

 speculated that benefits might in- 

 crease after the land had been 

 farmed for a longer time and further 

 experiments determined the most 

 effective methods of using green 

 manures. 



Soil-management problems of the 

 United States were discussed by 

 regions in the 1957 Yearbook of 

 Agriculture (33, 63). The United 

 States was divided into 16 regions. 

 Each of the regions had a combina- 

 tion of climate, soils, and agriculture 

 that gave it unique soil-manage- 

 ment problems. A brief summary 

 of statements concerning the use of 

 legumes and grasses in the northern 

 and part of the central Great Plains 

 follows: 



Northern Great Plains. — Norum, 

 Krantz, and Haas (63) reported 

 that, generally, it was not profitable 

 to plow under sweetclover, peas, or 

 winter rye for green manure and 

 fallow for the rest of the season in 

 the spring wheat subregion, except 

 in years of above-average precipita- 

 tion. The gains achieved in favor- 

 able years were lost in dry years. 



Winter Wheat and Grazing Re- 

 gion. — This area includes south- 

 western Nebraska, eastern Colo- 

 rado, western three-fourths of Kan- 

 sas, northwest Oklahoma and 

 Texas, and northeastern New 

 Mexico. Hobbs (33) reported that 

 sweetclover grew well in the more 

 humid areas of the eastern half of 

 Kansas and in Oklahoma east of 

 the Panhandle, but there was little 

 benefit from using sweetclover 



solely as green manure. Almost as 

 good results were obtained from 

 pasturing it or using it as a hay 

 or seed crop or by omitting the 

 legume entirely (especially in the 

 main wheat areas) and by using 

 nitrogenous fertilizer. Hobbs made 

 no mention of the use of legumes 

 and grasses in the area where 

 summer fallowing is commonly 

 used. 



In 1959, Stickler and coworkers 

 (78) reported on the comparative 

 value of legume green manures 

 and fertilizer nitrogen for corn 

 production in Iowa for 1955-57. 

 They found that the mean corn- 

 producing value of nitrogen from 

 19 legume green manures, as deter- 

 mined by first- and second-year 

 corn data, was equivalent to 34 

 and 64 pounds per acre of inor- 

 ganic nitrogen, respectively. Ma- 

 drid sweetclover was superior to 

 all other legumes as a green manure. 



North Dakota 



Yields 



Green-manure experiments were 

 conducted at Dickinson, Edgeley, 

 Hettinger, Mandan, and Williston, 

 N. Dak., beginning in 1906 (10, 18, 

 57, 71). Yields of spring wheat 

 and oats after green-manure fallow, 

 continuous cropping, and ordinary 

 fallow are presented (table 1). 



In 1925, Moomaw (57) reported 

 on tillage and rotation experiments 

 at Dickinson, Hettinger, and Willis- 

 ton. Average annual precipitation 

 was 15.4 inches at Dickinson, 14.2 

 inches at Hettinger, and 14.1 inches 

 at Williston. His findings show 

 that bromegrass and alfalfa were 

 the most productive perennial hay 

 crops for the area, but were of 

 doubtful value in short rotations. 

 Grain yields were not increased 

 by sod crops in the rotation. 

 Stand-establishment difficulties re- 

 duced the yields of hay below a 

 profitable point for the period the 



