{"id":672,"date":"2011-10-05T19:06:59","date_gmt":"2011-10-06T01:06:59","guid":{"rendered":"http:\/\/anthony.darrouzet-nardi.net\/scienceblog\/?p=672"},"modified":"2011-10-05T19:06:59","modified_gmt":"2011-10-06T01:06:59","slug":"what-forms-of-n-are-available","status":"publish","type":"post","link":"http:\/\/scienceblog.darrouzet-nardi.net\/?p=672","title":{"rendered":"What forms of N are available?"},"content":{"rendered":"<p>In the old days, it was assumed that the N uptake by plants and microbes was done via the labile currency of inorganic N ions: nitrate and ammonium. Later, it was discovered that plants and microbes could in fact take up amino acids as well, in a way &#8220;short-circuiting&#8221; the inorganic N part of the cycle. This leads to the question: what forms of N are actually taken up in the soil? A couple of interesting recent studies shed some light on this question and provide some good data suggesting that our understanding of labile N exchange is not complete.<\/p>\n<p>Using pool dilution techniques, <a href=\"http:\/\/dx.doi.org\/10.1016\/j.soilbio.2010.04.001\">Wanek et al.<\/a> show that:<\/p>\n<blockquote><p>&#8230;gross protein depolymerization exceeded gross N mineralization by &gt;8 fold indicating that only a small fraction of amino acids released by extracellular enzymes was actually mineralized to ammonium.<\/p><\/blockquote>\n<p>Not only could litter microbes take up amino acids, but they seemed to snag them quickly enough that the inorganic N forms were never produced. These things are hard to measure so this is impressive.<\/p>\n<p>Perhaps even more intriguing though, <a href=\"http:\/\/dx.doi.org\/10.1029\/2010GB003999\">Farrell et al.<\/a>\u00a0conclude:<\/p>\n<blockquote><p>Our findings&#8230;point to a short-circuit whereby large peptides and proteins need only be extracellularly cleaved to short chain length peptides before direct assimilation by microbes.<\/p><\/blockquote>\n<p>This is a big deal because it means to understand labile N pools in soils, we may need to do a lot more than just measure inorganic N and amino acids; currently, most people don&#8217;t even measure amino acids.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the old days, it was assumed that the N uptake by plants and microbes was done via the labile currency of inorganic N ions: nitrate and ammonium. Later, it was discovered that plants and microbes could in fact take up amino acids as well, in a way &#8220;short-circuiting&#8221; the inorganic N part of the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/posts\/672"}],"collection":[{"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=672"}],"version-history":[{"count":13,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/posts\/672\/revisions"}],"predecessor-version":[{"id":685,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=\/wp\/v2\/posts\/672\/revisions\/685"}],"wp:attachment":[{"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=672"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/scienceblog.darrouzet-nardi.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}