Cromack, K. Jr.; Delwiche, C. C.; McNabb, D. H. 1979. Prospects and problems of nitrogen management using symbiotic nitrogen fixers. In: Gordon, J. C.; Wheeler, C. T.; Perry, D. A., eds. Symbiotic nitrogen fixation in the management of temperate forests: proceedings of a workshop; 1979 April 2-5; Corvallis, OR. Corvallis, OR: Forest Research Laboratory, Oregon State University: 210-223.
Establishment of N fixing species, degree of nodulation, and rates of N fixationare affected by basic life history of the species concerned, by physical andchemical site factors and by interactions with other plant species. The role ofN fixing species in nutrient cycling can be assessed by direct measurement of Nfixation rates utilizing acetylene reduction or 15N labeling techniques. Alter-natively, total ecosystem N accretion rates, including the soil organic matter andabove and below-ground biomass, have been obtained in a number of differentstudies. Recycling of N by N fixing species is dependent upon rates of decomposi-tion of litter components; data from several such species suggest that both C andN substrate quality in N fixing species generally is higher than for non-N fixingspecies on the same sites. Prospects and problems of N management are viewed inthe overall context of site preparation for N fixation, coupled with management ofhigh quality N litter residue. A new technique of screening for potential new Nfixers in mixed plant communities is discussed.