4 i^ATIVE LEGUMES IN NEBRASKA AND KANSAS. 



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sizes and ages on its roots. These masses on old roots are sometimes 

 2 inches in diameter and an inch deep. Under date of September 18, 

 1909, Mr. Karl F. Kellerman, Soil Bacteriologist in the Bureau of 

 Plant Industry, wrote as follows concerning the specimens sent in 

 from North Platte : 



Referring to the roots and nodules of Lcparyyraea aryentea, the results of analyses 

 recently reported to us from the Bureau of Chemistry are as follows: Nitrogen, per- 

 centage of root, 0.43; nitrogen, percentage of nodules, 2.31. 



That the largely increased nitrogen content of the nodules is caused by the bacteria 

 is evidenced by the fact that we have succeeded in obtaining from your specimens 

 good cultures of nitrogen-fixing organisms. 



METHOD OF OBTAINING AVERAGES. 



In order to make the averages given in this circular comparable with 

 those in Circular 31 of the Bureau of Plant Industry, the total number 

 of plants has been divided by the total number of square yards 

 counted. This, however, does not give what is really wanted. Each 

 plat counted is assumed to be fairly representative of the tract from 

 which it was chosen, and some care was taken that it shoidd be. In 

 some cases it was necessary to count much larger plats than in otliere 

 in order to get counts w^hich seemed representative; therefore, each 

 plat and not each square yard should be given the same value. To 

 get this the mean of the column headed ''Average per square yard" 

 should have been taken. The correct average number of legumes to 

 the square yard on the tracts where observations were made in 1909 

 is 17.93, and for 1908, 21.58 (instead of 17.03 as given in the circular 

 mentioned). The average for both years is 19.34. These figures 

 seem surprisingly close together for observations made over so wide 

 an area. It will be noticed also that most of the counts made in 1908 

 were in the rolling countiy of eastern Nebraska and Kansas, while a 

 large part of those made in 1909 were on the level lands of south- 

 central Nebraska. 



PROPORTION IN WHICH DIFFERENT GENERA ARE FOUND. 



In 1 909 counts were made on 22 plats, and 4,539 legumes were found. 

 These were distributed among the different genera as follows: 



2,975 Psoralea, found on 20 out of the 22 plats. 

 519 Amorpha, found on 14 out of the 22 plats. 

 181 Kuhnistera, found on 8 out of the 22 plats. 

 139 Astragalus, found on 13 out of the 22 plats. 

 560 Vicia, found on 6 out of the 22 plats. 

 56 Lotus, found on 3 out of the 22 plats. 

 18 Aragallus, found on 6 out of the 22 plats. 

 5 Baptisia, found on 3 out of the 22 plats. 

 74 Lespedeza, found on 3 out of the 22 plats. 

 10 Morognia, found on 1 out of the 22 plats. 

 2 Meibomia, found on 2 out of the 22 plats. 

 ICir. 70] 



