Prolonged elevated atmospheric CO2does not affect decomposition of plant material

Prolonged elevated atmospheric CO2 might alter decomposition. In a 90-day incubation study, we determined the long-term (9 years) impact of elevated CO2 on N mineralization of Lolium perenne and Trifolium repens plant material grown at ambient and elevated CO2 and low- and high-N-15 fertilizer additions. No significant differences were observed in N-15-NO3- recovery rates between any of the treatments, except an N addition effect was observed for L perenne (0.4 versus 0.5% N-15-NO3- day(-1) in high versus low N). The results suggest that elevated CO2 did not change plant N mineralization in any of the soils, because of a surplus of available N in the fertilized and leguminous systems, and because of insignificant plant responses to elevated CO2 in the low soil N availability systems. (c) 2005 Published by Elsevier Ltd.