Molybdenum cocktails stimulate nitrogen fixation in tropical forests
December 23, 2008
Tropical forests represent a third of the total biomass on Earth and play a critical but poorly understood role in the carbon-climate system
Tropical forests represent a third of the total biomass on Earth and play a critical but poorly understood role in the carbon-climate system. Nitrogen fixation affects plant growth and a suite of processes including carbon exchange.
Researchers from Princeton and STRI show that the trace element molybdenum can limit nitrogen fixation in tropical forests. The prevailing view of tropical nitrogen fixation limited by the macro-nutrients phosphorus and nitrogen ought to be reconsidered, suggest Alexander Barron, lead author of an article published online in Nature Geosciences (December 9).
Little is known about factors affecting the way that nitrogen enters tropical ecosystems. Molybdenum, a soil nutrient found in very small quantities, is a key component that limits nitrogen fixation in agricultural legume crops.
Barron (left in the photo with assistant Aaron Strong) worked on Gigante peninsula within BCNM experimenting with plots exposed to fertilization treatments four times per year since 1998. Long-term fertilization with nitrogen, phosphorus and micro-nutrients caused clear shifts in the abundance of nitrogen, phosphorus and molybdenum in soil, with increased molybdenum levels in both the micro-nutrient and phosphorus treatments. Nitrogen fixation may be limited not only in acidic tropical soils, but also where molybdenum is in short supply. These results raise new questions about the potential role that trace metals may play in terrestrial ecosystems, especially how they might limit plant growth under high carbon dioxide conditions-essential to understanding global warming..
Story: Beth King (*)
Edited by M Alvarado & ML Calderon
Photo: MA Guerra
(*) Based on: Barron, Alexander R., Wurzburger, Nina, Bellinger, ean-Philippe Bellinger, Wright, S. Joseph, Kraespiel, Anne M.L. & global. Hedin, Lars O. 2008. "Nitrogen fixation in tropical soils limited by molybdenum availability. Nature Geosciences online.
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