Anoxic conditions maintained high phosphorus sorption in humid tropical forest soils

Yang Lin, Avner Gross, Christine S. O'Connell, Whendee L. Silver

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


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&thinsp;<span classCombining double low line"inline-formula">d</span> 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&thinsp;% of the added P disappearing from the solution within 6&thinsp;<span classCombining double low line"inline-formula">h</span>. 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 <span classCombining double low line"inline-formula">NaHCO3</span> 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.

Original languageEnglish
Pages (from-to)89-101
Number of pages13
Issue number1
StatePublished - 7 Jan 2020

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes


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