206 Nitrogen Fixation— Nonsvni])iotic 



Further information on the inability of nonsymbiotic nitrogen-fix- 

 ing bacteria to supply available nitrogen when natural plant residues 

 high in cellulose are added to the soil is found in Tables 44 and 45. 



TaBLK 44. I.NKH'KNCK OF Si (iAIi ll'ON CuDI' ^'IK1,I) AND NiTllOfiKN CoNTKXT OF ( 'ifOI' 



(from .\. Kocli) 



(irams ol' dry suhstaiicc per \m>\, lor IS-ycar ix'rioil. 



Control (ihicosc * Sucroso Sucrose 



Crop yield 4^20 . .J 4S() . 7 49^2 . i oii . 6 



Excess over control (iO.'-l li.l ]'ii.l 



IVlilliiiranis of Nitrofjcn in Crop 

 Nitrogen '•2,.'5(i:5 ^2,!)1(> .3, 000 .'5,040 



Excess over control .m.S 0.'57 1,'28.'5 



* .'500 gni of sugars added, over the IS-year |)eriod, to llic treated j)ols. 



Tabi.e 4.5. IxFLTfEN'CK OF Celu'lose I'pox (]rop Yikld (froiH A. Kr)cll) 

 (iranis of dry suhstance jx-r i)ot, for ;5-year periods. 



Total cro]) -2.">9.;) '24f5.0 •200.8 '2fifi.7 



With glucose and sucrose as sources of energy, considerable nitrogen 

 was fixed. With cellulose, on the other hand, there was no increase 

 in the nitrogen supply even after 11 years' treatment. Unfortunately, 

 plant residues that usually find their way into the soil are poor in 

 sugar and rich in cellulose. 



Selected Bibliography 



1. Allison, F. K., llooNcr, S. 1^, antl Morris, II. J., Pli\siological studies with 

 tlie nitrogen-fixing alga Nostur mitsconim, Botan. (laz., 98:433-463, 1937. 



2. Bond, G., Quantitati\e observations on the fixation and transfer of nitrogen 



