Iron reduction and soil phosphorus solubilization in humid tropical forests soils: The roles of labile carbon pools and an electron shuttle compound
Iron reduction and soil phosphorus solubilization in humid tropical forests soils: The roles of labile carbon pools and an electron shuttle compound
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DOI：
10.1007/s10533-005-2343-3
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发表时间：
2006-03-01
期刊：
影响因子：
4
通讯作者：
Cusack, DF
中科院分区：
文献类型：
--
作者：
Chacon, N;Silver, WL;Cusack, DF
氧化铁和氢氧化物对磷的亲和力被认为导致了酸性、高度风化土壤上的潮湿热带森林中磷对净初级生产力的限制。这些土壤中常年温暖、潮湿的条件和高生物活性会导致氧化还原电位波动，进而导致不稳定碳和腐殖质存在时铁的大量减少。我们研究了还原条件结合添加不稳定碳底物（葡萄糖和乙酸盐）和电子穿梭化合物对潮湿热带森林土壤中铁还原和磷释放的影响。在实验开始时将葡萄糖或醋酸盐作为单剂量添加到土壤中，并随着时间的推移作为脉冲输入，这更接近地模拟不稳定碳可用性的模式。单一低水平的碳添加以及添加或不添加碳的电子穿梭化合物对铁还原和磷迁移的刺激微弱。脉冲式不稳定碳添加显着提高了土壤 pH 值、可溶性铁和磷浓度。脉冲不稳定碳输入也促进了氢氧化亚铁络合物的沉淀，这可以增加磷吸附能力，尽管我们的结果表明磷溶解速率超过了再吸附。植物和微生物对磷的需求也可能成为释放磷的重要汇，限制磷再吸附的作用。我们的研究结果表明，还原条件与定期碳输入相结合可以刺激铁还原和土壤磷动员的相应增加，这可能为这些生态系统中以前未记录的植物和微生物提供磷源。
The affinity of iron oxides and hydroxides for phosphorus is thought to contribute to phosphorus limitation to net primary productivity in humid tropical forests on acidic, highly weathered soils. Perennially warm, humid conditions and high biological activity in these soils can result in fluctuating redox potential that in turn leads to considerable iron reduction in the presence of labile carbon and humic substances. We investigated the effects of reducing conditions in combination with the addition of labile carbon substrates (glucose and acetate) and an electron shuttle compound on iron reduction and phosphorus release in a humid tropical forest soil. Glucose or acetate was added to soils as a single dose at the beginning of the experiment, and as pulsed inputs over time, which more closely mimics patterns in labile carbon availability. Iron reduction and phosphorus mobilization were weakly stimulated by a single low level addition of carbon, and the addition of the electron shuttle compound with or without added carbon. Pulsed labile carbon additions produced a significant increase in soil pH, soluble iron, and phosphorus concentrations. Pulsed labile carbon inputs also promoted the precipitation of ferrous hydroxide complexes which could increase the capacity for P sorption, although our results suggest that rates of P solubilization exceeded re-adsorption. Plant and microbial P demand are also likely to serve as an important sinks for released P, limiting the role of P re-adsorption. Our results suggest that reducing conditions coupled with periodic carbon inputs can stimulate iron reduction and a corresponding increase in soil phosphorus mobilization, which may provide a source of phosphorus to plants and microorganisms previously undocumented in these ecosystems.