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Phosphorus availability and elevated CO 2 affect biological nitrogen fixation and nutrient fluxes in a clover‐dominated sward
Author(s) -
Edwards Everard J.,
McCaffery Stephanie,
Evans John R.
Publication year - 2006
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2005.01568.x
Subject(s) - trifolium repens , nutrient , phosphorus , agronomy , nitrogen , pasture , chemistry , zoology , nitrogen fixation , mesocosm , biology , organic chemistry
Summary• The response of biological nitrogen fixation (BNF) to elevated CO 2 was examined in white clover ( Trifolium repens )‐dominated swards under both high and low phosphorus availability. • Mixed swards of clover and buffalo grass ( Stenotaphrum secundatum ) were grown for 15 months in 0.2 m 2 sand‐filled mesocosms under two CO 2 treatments (ambient and twice ambient) and three nutrient treatments [no N, and either low or high P (5 or 134 kg P ha −1 ); the third nutrient treatment was supplied with high P and N (240 kg N ha −1 )]. • Under ambient CO 2 , high P increased BNF from 410 to 900 kg ha −1 . Elevated CO 2 further increased BNF to 1180 kg ha −1 with high P, but there was no effect of CO 2 on BNF with low P. Allocation of N belowground increased by approx. 50% under elevated CO 2 irrespective of supplied P. • The results suggest that where soil P availability is low, elevated CO 2 will not increase BNF, and pasture quality could decrease because of a reduction in aboveground N.