Phosphorus availability and elevated CO2 affect biological nitrogen fixation and nutrient fluxes in a clover-dominated sward

Everard J. Edwards*, Stephanie McCaffery, John R. Evans

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    65 Citations (Scopus)

    Abstract

    • The response of biological nitrogen fixation (BNF) to elevated CO2 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 m2 sand-filled mesocosms under two CO2 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 CO2 further increased BNF to 1180 kg ha-1 with high P, but there was no effect of CO2 on BNF with low P. Allocation of N belowground increased by approx. 50% under elevated CO2 irrespective of supplied P. • The results suggest that where soil P availability is low, elevated CO2 will not increase BNF, and pasture quality could decrease because of a reduction in aboveground N.

    Original languageEnglish
    Pages (from-to)157-167
    Number of pages11
    JournalNew Phytologist
    Volume169
    Issue number1
    DOIs
    Publication statusPublished - Jan 2006

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