Elevated CO2 temporally enhances phosphorus immobilization in the rhizosphere of wheat and chickpea
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The efficient management of phosphorus (P) in cropping systems remains a challenge due to climate change. We tested how plant species access P pools in soils of varying P status (Olsen-P 3.2–17.6 mg kg−1), under elevated atmosphere CO2 (eCO2).
Chickpea (Cicer arietinum L.) and wheat (Triticum aestivum L.) plants were grown in rhizo-boxes containing Vertosol or Calcarosol soil, with two contrasting P fertilizer histories for each soil, and exposed to ambient (380 ppm) or eCO2 (700 ppm) for 6 weeks.
The NaHCO3-extractable inorganic P (Pi) in the rhizosphere was depleted by both wheat and chickpea in all soils, but was not significantly affected by CO2 treatment. However, NaHCO3-extractable organic P (Po) accumulated, especially under eCO2 in soils with high P status. The NaOH-extractable Po under eCO2 accumulated only in the Vertosol with high P status. Crop species did not exhibit different eCO2-triggered capabilities to access any P pool in either soil, though wheat depleted NaHCO3-Pi and NaOH-Pi in the rhizosphere more than chickpea. Elevated CO2 increased microbial biomass C in the rhizosphere by an average of 21 %. Moreover, the size in Po fractions correlated with microbial C but not with rhizosphere pH or phosphatase activity.
Elevated CO2 increased microbial biomass in the rhizosphere which in turn temporally immobilized P. This P immobilization was greater in soils with high than low P availability.
KeywordsClimate change Elevated CO2 Microbial biomass C P fractions Phosphatase Rhizosphere acidification
This research was supported by an Australian Research Council Linkage Project (LP100200757), and utilised the SoilFACE facility of the Department of Primary Industries, Victoria at Horsham. We thank anonymous reviewers for their comments on the manuscript.
- FAO-UNESCO (1976) Soil Map of the World, 1:5 000 000, vol X. UNESCO, ParisGoogle Scholar
- Isbell RF (1996) The Australian soil classification. CSIRO Publishing, MelbourneGoogle Scholar
- Marschner H (1995) Mineral nutrition of higher plants. Academic, LondonGoogle Scholar
- Rayment GE, Higginson FR (1992) Australian laboratory handbook of soil and water chemical methods. Inkata Press, MelbourneGoogle Scholar
- Richardson AE (2001) Prospects for using soil microorganisms to improve the acquisition of phosphorus by plants. Aust J Plant Physiol 28:897–906Google Scholar
- Skujins JJ, Braal L, McLaren AD (1962) Characterization of phosphatase in a terrestrial soil sterilized with an electron beam. Enzymologia 25:125–133Google Scholar
- Steel RG, Torrie JH (1980) Principles and procedures of statistics: A biometrical approach, 2nd edn. McGraw-Hill, New YorkGoogle Scholar
- Wang X, Guppy CN, Watson L, Sale PWG, Tang C (2011) Availability of sparingly soluble phosphorus sources to cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) with different forms of nitrogen as evaluated by a 32P isotopic dilution technique. Plant Soil 348:85–98CrossRefGoogle Scholar
- White ME (1986) The greening of Gondwana. The 400 million year story of Australian plants. Reed Books, Frenchs ForestGoogle Scholar