Jurgensen, Martin F.; Tonn, Jonalea R.; Graham, Russell T.; Harvey, Alan E.; Geier-Hayes, Kathleen. 1990. Nitrogen fixation in forest soils of the Inland Northwest. In: Harvey, Alan E.; Neuenschwander, Leon F., compilers. Proceedings - management and productivity of western-montane forest soils; 1990 April 10–12; Boise, ID. Gen. Tech. Rep. INT-280. Ogden UT: U. S. Department of Agriculture, Forest Service, Intermountain Research Station.
Significant amounts of soil nitrogen (N) are lost from the soil during timber harvesting and related activities. Symbiotic N-fixing plants have the potential to replace much of these N losses on many sites in the Inland Northwest, especially during early stand development. However, many of these plants are site specific and can cause competition problems during stand establishment. Much more information is needed on the successional roles of N-fixing plants in Inland Northwest forests. Nonsymbiotic N fixation in forest soils of this region is low, but is an important source of N on sites where N-fixing plants are lacking or of low frequency. Appreciable amounts of N can be added to the soil by nonsymbiotic N fixation over long stand rotation ages typical for this region. Silvicultural systems need to be developed that minimize soil N losses and maintain the biological N fixation potential of the site.