LEGUMES AND GRASSES 



49 



Table 32. — Organic carbon in surface 6 inches of virgin soils and soils 

 cropped for an average of 37 years and the total and per-year percentage 

 loss caused by cropping, 10 locations in the northern and central Great 

 Plains 1 





Cropping 

 period 



Years 



of 

 crop- 

 ping 



Organic-carbon content 



Location 



Virgin 

 soils 



Cropped 

 soils 



Loss 

 with 

 crop- 

 ping 



Loss per 

 year of 

 crop- 

 ping 



Mandan, N. Dak 



Dickinson, N. Dak 



Havre, Mont 



1913-43 



1907-47 

 1916-47 

 1908-47 

 1917-47 

 1913-47 

 1908-47 

 1905-46 

 1903-46 

 1907-46 



Number 

 30 

 40 

 31 

 39 

 30 

 34 

 39 

 41 

 43 

 39 



Percent 



2. 11 



3. 64 

 1.75 

 3. 24 

 1. 66 

 1.33 

 1. 42 

 1.83 

 2.47 

 1. 13 



Percent 



1. 45 

 1.51 



.83 



2. 19 

 1. 19 



.78 



.77 



1.01 



1. 21 



. 69 



Percent 

 31 

 59 

 53 

 32 

 28 

 41 

 46 

 45 

 51 

 39 



Percent 

 1.03 

 1.48 

 1. 71 



Moccasin, Mont 



Sheridan. Wyo_ 



.85 

 . 93 



Archer, Wvo 



1. 21 



Akron, Colo 



1. 18 



Colby, Kans 



1. 10 



Havs, Kans__ 



1. 19 



Garden City, Kans 



1.00 



Mean _ _ 





37 



2. 06 



1. 16 



42 



1. 17 









Data from Haas and coworkers (27) . 



Table 33. — Losses of nitrogen from surface and subsurface soils compared 

 with virgin sod in rotations with and without green manure at 10 locations 

 in the northern and central Great Plains, 1903-47 1 2 





Loss of nitrogen at — 



Location 



0- to 6-inch depth 



6- to 12-inch depth 





No 



green 



manure 



Rye 



green 

 manure 



Legume 



green 



manure 



No 



green 



manure 



Rye 



green 

 manure 



Legume 



green 



manure 



Mandan, N. Dak _ _ 



Percent 

 31 

 50 

 37 

 32 

 21 

 34 

 37 

 28 

 18 

 18 



Percent 

 32 

 48 

 36 



18" 



30 



37 



27 

 14 

 22 



Percent 

 30 

 50 



32" 



19 



33 



33 



30 



17 



Percent 

 13 

 37 

 15 



Percent 



13 



31 



6 



Percent 

 8 



Dickinson, N. Dak 



Havre, Mont 



35 



Moccasin Mont - - 





Sheridan Wyo - - 



3 10 

 6 



8 



36 



4 



8 



3 7 



Archer Wyo 



6 



Akron Colo 



3 















Garden City, Kans 

















Mean 



31 



29 



30 



15 



11 



12 







i Data from Haas and coworkers (27) . 



2 Periods of cropping varied from 30 to 40 years. 



3 Sampling depth was 6 to 20 inches. 



