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Sections Home Page Local News AP News Archives Business Classifieds Event Calendar Forums Life Opinion Obituaries Photo Gallery Since We Asked Sports Tempo Weather Special Coverage 2006 Britt Festivals --> Shop Our Valley AutoFinder HomeFinder JobFinder Search Our Valley Special Sections Homelife Magazine Joy Magazine Readers Choice 2006 Oregon Golf Info Oregon Wine Info Our Valley Other Publications Local Links Ashland News eSouthernOregon Newspapers In Education Personals Moving Here Movie Listings TV Listings Volunteer Customer Service Advertise With Us Media Kit Place Classified Ad Contact Us FAQ's Home Delivery Site Map --> Email Story to a Friend August 11, 2006 Alders can contribute up to 120 pounds of nitrogen per acre to the soil a year in cooperation with nitrogen-fixing bacteria. This red alder, seen in closeup, is common to the Pacific Northwest. Plants help bacteria add soil nitrogen Ground often needs more of this element for good plant growth It just doesn't seem to make sense. We breathe 2,000 gallons of air per day and 1,600 gallons (80 percent) is nitrogen. Nitrogen is essential for all life. It is all around us, all day every day, yet it is commonly the most limiting element for plant growth on earth. There is very little nitrogen available to plants in the soil. Yes, it seems contradictory, "abundant" but limiting. Ecosystems and species have constantly evolved and survived with one simple rule: keep what works and abandon failure or inefficiency (possibly a good long-term strategy for political systems too). So over the years, more and more engineers have looked to species adaptations for solutions to structural, thermal, and mechanical issues that natural selection has long ago solved. Therefore, it is difficult for me to believe that not taking nitrogen from the air is a problem. Well, in fact, some plants do use nitrogen directly: bacteria (see the June 16 Ecological Perspectives column on how little things run the world). Nitrogen-fixing bacteria (look up rhizobium) bond with legumes (the pea family), alder, snowbrush ceanothus, lichens, bitterbrush and a few other species. Their relationship is symbiotic (mutually advantageous) and results in non-inert nitrogen compounds that other plants can also use, and at no extra charge. Advertisement Lightning also fixes nitrogen. It can add about 10 pounds per acre per year. But does that satisfy ecosystem needs? Not likely. Recommended applications for gardens and agricultural crops can be between 150 and 200 pounds to avoid deficiencies. While garden application is easily controlled and agriculture crops are monitored and tended, forests are expected to manage on their own. But, they have help. Ceanothus, aka snowbrush or slickleaf, can fix 20 pounds per acre a year. It was once only considered a competitive antagonist, but is becoming recognized now as a long-term benefit to site productivity. Several species of ceanothus occur throughout the Rogue Basin and each contributes to the store of soil nitrogen. Although alder is more limited in range than snowbrush ceanothus, it is usually, but not always found in riparian areas, and wet or moist sites. According to several sources, a pure stand of alder can fix more than 120 pounds per acre a year. It doesn't take long for alders to contribute to overall forest health. However, the pea family members are the champion fixers. Vetch can fix about 70 pounds per acre a year but trifolium, a clover, can fix more than 200 pounds. That is partly why clover and alfalfa are used in agricultural crop rotations. The rest of the story is that they are an inexpensive means of adding a stable source of nitrogen. Moreover, plowing them under adds carbon and structure to the soil. Gardeners might also consider legumes in their planting and rotations. I stopped trying to have the "perfect" lawn by weeding out the clover and then adding nitrogen to keep it green decades ago, and it still looks good from afar (satellite images). It just seemed wrong, maybe even crazy, to pay to kill a natural nitrogen fixer and then have to add nitrogen for my indiscretion. I think the saying is "insult to injury." Our forests have quite a number of pea family members. Lupine, wild pea, lotus and locoweed are common and likely help supply the ecosystem with nitrogen. But few have been adequately assayed for fixation rates. Still, our early research in the Ashland Watershed project (1969) indicated that both the soil and plant tissues often lacked sufficient nitrogen, although it was in our every breath. Well, maybe abundance with limits does make sense. It is an ecological axiom that species develop to the limits their environment will allow. Limits and need help provide the stress that selects winning characteristics. Species with "silver-spoon" syndrome may not acquire the hardiness needed for long-term survival. Taking nitrogen straight from the air may be too easy. Tom Atzet is a retired Forest Service ecologist living in Merlin. He can be reached at P.O. Box 1226, Merlin, OR 97532. Mail Tribune Home | Local News | Sports | Business | Obituaries | Life | Opinion AP News | Archives | Site Map | Community | Classified Copyright © 1997-2006 Mail Tribune, Inc. All rights reserved. Privacy Policy | Terms & Conditions | Website Feedback online casinos news Home Security Systems California Casinos Men's Clothing Southern Oregon Loans --> GMAT Prep Fundraisers Send Flowers Entertainment Guide --> Casinos Canada Trunks, Footlocker Online Casino Reviews Advertisement s Advertisement