ORGANIC MATTER AND NITROGEN 



221 



when nothing better can be had, it is not to be compared with 

 red clover or alfalfa for either purpose, but it does give promise 

 of great value as a green manure crop, and it seems appropriate 

 to emphasize the fact that the 6.4 tons of dry matter furnish as 

 much humus-forming material and as much nitrogen as would be 

 furnished by 25 tons of average farm manure. 



In the Wisconsin experiments above referred to, the infected 

 soy beans contained in their roots about 4 per cent, 6 per cent, and 

 5 per cent, of their nitrogen, phosphorus, and potassium, respec- 

 tively; and in the Michigan experiments the corresponding figures 

 are about 4 per cent, 6 per cent, and 6 per cent, respectively. 



From an exhaustive investigation of the crimson-clover plant 

 (Trifolium incarnatum) , Penny (Delaware Bulletin 67) reports the 

 following average results' for fall-seeded crops harvested about 

 May 15, when nearly in full bloom: 



TABLE 35. COMPOSITION OF CRIMSON CLOVER IN BLOOM 

 Delaware Experiments : Pounds per Acre 



PERCENTAGE OF TOTAL 



The proportions were found to vary considerably, but this gen- 

 eral average shows the crimson-clover roots (to a depth of 24 

 inches) to contain less than one third of the organic matter, 

 nitrogen, and phosphorus, and less than one fifth of the potassium 

 of the entire plant. It was found that 77 per cent of the roots were 

 in the first 6 inches of soil, and 1 3 per cent in the second 6 inches, 

 7 per cent in the third, and 3 per cent in the fourth 6 inches. 



In Table 36 are recorded much additional information concern- 



