SOILS AND FERTILIZERS 503 



richer in protein. The seed is also cheaper than that of cowpeas, 

 usually costing only two-thirds as much. This is principally due to 

 the fact that the seed can readily be harvested by machinery. It 

 also has an advantage in that the seeds are but little affected by wee- 

 vils. On these accounts soy beans are preferred by an increasing 

 number of farmers in the South. Soy beans, however, are not able 

 to compete with weeds as successfully as cowpeas, and on this ac- 

 count the best results are obtained by planting in rows, so that they 

 may be cultivated. There is considerable difficulty experienced at 

 first in obtaining tubercles on the roots of soy beans, but when once 

 these have appeared in a particular piece of ground there is no 

 further trouble. Apparently, soy beans have a greater power than 

 cowpeas to absorb atmospheric nitrogen through their roots. 



In an investigation conducted at the Michigan Agricultural 

 Experiment Station it was found that inoculated soy beans were en- 

 abled to add per acre 37.57 pounds of nitrogen provided from the 

 air. At the Arkansas Agricultural Experiment Station soy beans 

 used as green manure gave nearly as good results as cowpeas, as de- 

 termined by subsequent crops of wheat, oats, cotton, and corn. 

 With cotton, the soy bean vines produced a larger yield of cotton 

 than cowpea vines, but the cowpea stubble gave a larger yield than 

 the soy bean stubble. With corn, cowpea stubble and soy bean stub- 

 ble yielded the same results, while soy bean vines gave better results 

 than the cowpea vines. With oats, the results were slightly^ in favor 

 of the cowpeas. It is not improbable that the variation in results 

 may be largely due to variation in the amounts of atmospheric ni- 

 trogen added by the legumes to the different plats. Those that were 

 most heavily tubercled would add the most nitrogen. 



Velvet beans have been tested in comparison with cowpeas at 

 the Arkansas and Alabama agricultural experiment stations. The 

 velvet bean is somewhat objectionable on account of the very viny 

 habit of the plant, which renders it difficult to plow under. In or- 

 chards velvet beans have been found objectionable on account of 

 their tendency to climb the trees. At the Arkansas Agricultural 

 Experiment Station velvet beans gave better results on a subsequent 

 crop of cotton than either soy beans or cowpeas, the velvet bean plat 

 yielding 1,550 pounds of seed cotton, against 1,448 pounds for the 

 soy beans and 1,335 pounds for the cowpeas. With wheat, velvet 

 bean stubble gave better results than either cowpea stubble or soy 

 bean stubble, though the difference was very slight. It is note- 

 worthy also that velvet bean stubble gave much better results on the 

 succeeding crop of wheat than where the whole crop of velvet bean 

 vines was plowed under, and the same was true in regard to both cow- 

 peas and soy beans. In all cases, however, there was a marked in- 

 crease of crop, due to the influence of the legumes. 



At the Alabama Agricultural Experiment Station the following 

 yields of sorghum hay were obtained : After fallow, 3,792 pounds per 

 acre ; after cowpeas plowed under, 7,008 pounds ; after velvet beana 

 plowed under, 7,064 pounds. Here the legumes nearly doubled the 

 yield of the sorghum hay, the velvet beans being slightly better than 



