Faster redox fluctuations can lead to higher iron reduction rates in humid forest soils

Barcellos, Diego; Cyle, K. Taylor; Thompson, Aaron

doi:10.1007/s10533-018-0427-0

Cited by 49 publications

(44 citation statements)

References 75 publications

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“…The type of redox environment likely influences the responses of soil P and Fe pools, especially during redox oscillations. By employing anoxic glove box with 5% H 2 and using soil slurries with addition of organic matter, Barcellos et al () and Ginn et al () showed that repeated redox oscillation increased the redox sensitivity of amorphous Fe minerals, eventually resulting in comparable Fe(II) concentrations between fluctuating redox and static anoxic treatments. Their designs likely stimulated Fe reduction and created stronger reducing conditions than those in our experiment achieved with headspace manipulation.…”

Section: Discussionmentioning

confidence: 99%

“…Phosphorus bound to amorphous minerals may be particularly sensitive to redox oscillation given the high redox sensitivity of amorphous Fe (Liptzin & Silver, ; Thompson et al, ). Recent studies found that frequent shifts in redox conditions led to more rapid Fe reduction and greater accumulation of Fe(II) (Barcellos et al, ; Ginn et al, ). It is likely that these strong Fe reduction responses might also result in greater increases in P solubility under more frequent oscillation regimes.…”

Section: Introductionmentioning

confidence: 99%

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Phosphorus Fractionation Responds to Dynamic Redox Conditions in a Humid Tropical Forest Soil

et al. 2018

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Phosphorus (P) is a key limiting nutrient in highly weathered soils of humid tropical forests. A large proportion of P in these soils is bound to redox-sensitive iron (Fe) minerals; however, little is known about how Fe redox interactions affect soil P cycling. In an incubation experiment, we changed bulk soil redox regimes by varying headspace conditions (air versus N 2 gas) and examined the responses of soil P and Fe species to two fluctuating treatments (4-or 8-day oxic followed by 4-day anoxic) and two static redox treatments (oxic and anoxic). A static anoxic headspace increased NaOH-extractable inorganic P and ammonium oxalate-extractable total P (AO-P t ) by 10% and 38%, respectively, relative to a static oxic headspace. Persistent anoxia also increased NaHCO 3 -extractable total P (NaHCO 3 -P t ) toward the end of the experiment. Effects of redox fluctuation were more complex and dependent on temporal scales. Ammonium oxalate-extractable Fe and P t concentrations responded to redox fluctuation early in the experiment, but not thereafter, suggesting a depletion of reductant over time. Immediately following a switch from an oxic to anoxic headspace, concentrations of AO-P t , AO-Fe, and HCl-extractable Fe(II) increased (within 30 min) but fell back to initial levels by 180 min. Surprisingly, the labile P pool (NaHCO 3 -P t ) decreased immediately after reduction events, potentially due to resorption and microbial uptake. Overall, our data demonstrate that P fractions can respond rapidly to changes in soil redox conditions, and in environments where redox oscillation is common, roots and microbes may benefit from these rapid P dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phosphorus Fractionation Responds to Dynamic Redox Conditions in a Humid Tropical Forest Soil

et al. 2018

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“…An interesting question for future studies is whether plant roots and microbes can take advantage of the increased P solubility during reducing events. Anaerobic conditions can be stressful for plants and microbes; however, studies have reported similar soil respiration rates under aerobic and anaerobic conditions in humid tropical forest soils (DeAngelis et al, 2010;Pett-Ridge, 2005;Bhattacharyya et al, 2018). Soil microbes appear to be well-adapted to dynamic redox conditions, at least at the scales of days to weeks.…”

Section: Implications For P Solubility and Bioavailabilitymentioning

confidence: 99%

Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

et al. 2020

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The strong phosphorus (P) sorption capacity of iron (Fe) and aluminum (Al) minerals in highly weathered, acidic soils of humid tropical forests is generally assumed to be an important driver of P limitation to plants and microbial activity in these ecosystems. Humid tropical forest soils often experience fluctuating redox conditions that reduce Fe and raise pH. It is commonly thought that Fe reduction generally decreases the capacity and strength of P sorption. Here we examined the effects of 14 d oxic and anoxic incubations on soil P sorption dynamics in humid tropical forest soils from Puerto Rico. Contrary to the conventional belief, soil P sorption capacity did not decrease under anoxic conditions, suggesting that soil minerals remain strong P sinks even under reducing conditions. Sorption of P occurred very rapidly in these soils, with at least 60 % of the added P disappearing from the solution within 6 h. Estimated P sorption capacities were much higher, often by an order of magnitude, than the soil total P contents. However, the strength of P sorption under reducing conditions was weaker, as indicated by the increased solubility of sorbed P in NaHCO 3 solution. Our results show that highly weathered soil minerals can retain P even under anoxic conditions, where it might otherwise be susceptible to leaching. Anoxic events can also potentially increase P bioavailability by decreasing the strength, rather than the capacity, of P sorption. These results improve our understanding of the redox effects on biogeochemical cycling in tropical forests.

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“…Redox effects on soil P sorption processes have not been well studied in tropical forest soils, even though periodic redox oscillations are well documented in these environments (Barcellos et al, 2018;Schuur et al, 2001;Chen et al, 2018;Keiluweit et al, 2016;Wieder et al, 2011;O'Connell et al, 2018;Silver et al, 1999). Some past studies from tropical ecosystems have reported increases in extractable soil P during anoxic events (Chacón et al, 2006;Peretyazhko and Sposito, 2005;Maranguit et al, 2017), which is consistent with the hypothesis that anoxic conditions weaken P sorption, although the mechanisms remain unclear.…”

Section: Introductionmentioning

confidence: 68%

Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

Yang¹,

Gross²,

O’Connell³

et al. 2019

Preprint

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Abstract. The strong phosphorus (P) sorption capacity of iron (Fe) and aluminum (Al) minerals in highly weathered, acidic soils of humid tropical forests is generally assumed to be an important driver of P limitation to plants and microbial activity in these ecosystems. Humid tropical forest soils often experience fluctuating redox conditions that reduce Fe and raise pH. It is commonly thought that Fe reduction generally decreases the capacity and strength of P sorption. Here we examined the effects of 14-day oxic and anoxic incubations on soil P sorption dynamics in humid tropical forest soils from Puerto Rico. Contrary to the conventional belief, soil P sorption capacity did not decrease under anoxic conditions, suggesting that soil minerals remain strong P sinks even under reducing conditions. Sorption of P occurred very rapidly in these soils, with at least 60&#8201;% of the added P disappearing from the solution within six hours. Estimated P sorption capacities were one order of magnitude higher than the soil total P contents. However, the strength of P sorption under reducing conditions was weaker, as indicated by the increased solubility of sorbed P in NaHCO3 solution. Our results show that highly weathered soil minerals can retain P even under anoxic conditions, where it might otherwise be susceptible to leaching. Anoxic events can also potentially increase P bioavailability by decreasing the strength, rather than the capacity, of P sorption. These results improve our understanding of the redox effects on biogeochemical cycling in tropical forests.

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Faster redox fluctuations can lead to higher iron reduction rates in humid forest soils

Cited by 49 publications

References 75 publications

Phosphorus Fractionation Responds to Dynamic Redox Conditions in a Humid Tropical Forest Soil

Phosphorus Fractionation Responds to Dynamic Redox Conditions in a Humid Tropical Forest Soil

Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

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