Spatial and temporal variation in soil Mn2+ concentrations and the impact of manganese toxicity on lucerne and subterranean clover seedlings

Richard Hayes, Mark Conyers, Guangdi Li, G. J. Poile, Jacqui Price, Brett McVittie, Matthew Gardner, Graeme A. Sandral, Jeffrey McCormick

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24 Citations (Scopus)


Abstract. Spatial and temporal variation in soilMn2+ was observed over a 12-month period at two field sites near Gerogeryand Binalong in southern New South Wales (NSW), Australia. Three pot experiments were then conducted to emulate therange of soil Mn2+ concentrations observed in the field and to determine the effect of different concentrations on lucerne andsubterranean clover seedling growth, as well as to determine the effect of heating a soil on pH and Mn2+ concentrations.Concentrations of soil Mn2+ in the surface 0.20mvaried at a given sampling date by up to 288% (2.5'9.7 mg/mL) and 183%(8.7'24.6 mg/mL) across the Gerogery and Binalong field sites, respectively. At both sites, the concentration of soilMn2+ in agiven plot also varied by up to 175% between sampling times. There was little consistency between sites for seasonalfluctuations of soil Mn2+, although in both instances, peaks occurred during months in which newly sown lucerne plantsmight be emerging in southern NSW. Pot experiments revealed that high concentrations of soil Mn2+ reduced lucerneseedling survival by 35%, and on seedlings that did survive, reduced shoot growth by 19% and taproot length by 39%.Elevated concentrations of soil Mn2+ also reduced subterranean clover seedling survival by up to 55% and taproot length by25%, although there were few effects on subterranean clover in treatments other than those imposing the highest soil Mn2+concentrations. The third pot experiment demonstrated that elevated soil temperatures led to increased soil pH and increasedsoilMn2+ concentrations, attributable to a decrease in biological oxidation of soilMn2+. This was in contrast to the commonlyanticipated response of a decline in soil Mn2+concentrations as soil pH increased.
Original languageEnglish
Pages (from-to)675-885
Number of pages211
JournalCrop and Pasture Science
Issue number9
Publication statusPublished - 2012


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