16 



Idaho Ecological Factors Influencing Free-Living Nitrogen -Fixing 

 Organisms in Certain Northern Soils, To determine (l) activity 

 of free-living N -fixing microorganisms in N.W. soils; (2) nutri- 

 tional requirements of these organisms; and (3) influence of 

 ecological factors in activity of N-fixing orgauiisms. 

 Bact., Agr. Chem. 214 



m. Biological Nitrogen Fixation by Symbiotic and Nonsvmbiotic 

 Nitrogen -Fixing Microorganisms, To (l) establish contributions 

 of each of symbionts, rhizobia and leguminous plants, to symbiotic 

 N-fixation process; (2) determine importance of inoculation of 

 leguminous crops grown on soils where nodulated crops have been 

 previously; and (3) evaluate importance of soil organic matter 

 in nonsyrabiotic nitrogen fixation in soils. 

 Agron. 15-391 



La. Microbiological Gains and Losses of Nitrogen in Soils. 



To study (l) in the field, relation of various cropping 

 practices to supply of N and influence of cropping practices 

 on accumulation or depletion rate of N and organic matter 

 content of soils and loss of N by leaching; (2) influence of 

 various cropping practices on numbers of non-symbiotic N-fixing 

 bacteria and value of these microorganisms in adding N to soil; 

 (3) isolate from soils microorganisms capable of living on 

 N-free medium and at different oxygen tensions and to study 

 their N-fixing capacity in pure and mixed cultures; (4) study 

 in greenhouse effects of artificial inoculation of seed, lime, 

 phosphorus, and potassium on symbiotic N fixation, nodule for- 

 mation and protein content of certain legumes grown in soils 

 of the lower Mississippi flood plain and terraces; and (5) 

 study in the lab the mechanisms involved in gains and losses 

 of N in these soils. 

 Soils 596 



Minn • The Activity of the Rhizosrhere Porttlation in Transforma - 

 tions of Nitrogen Within the Root Zone as Related to the Nutri - 

 tion of Plants. To clarify the action of the rhizosphere popula- 

 tion in the transformations of N within the root zone and the 

 relation of these transformations to the N nutrition of plants. 

 Soils 2515 



Miss. Nitrification and Fixation of Ammonia in Soils. To determine 

 (1) extent and conditions under which ammonium nitrogen is fixed 

 in a form which is unavailable to plants; (2) combined effect 

 of temperature and soil reaction on rate of nitrification of 

 ammonia; (3) relationship between ammonia retaining power and 

 lime requirement of soils; and (4) loss of N applied as anhydrous 

 amnonia after varying periods of time following application. 

 Agron. HD-2 



