Effects of drying and simulated flooding on soil phosphorus dynamics from two contrasting UK grassland soils
Effects of drying and simulated flooding on soil phosphorus dynamics from two contrasting UK grassland soils
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DOI：
10.1111/ejss.13196
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发表时间：
2021-11
影响因子：
4.2
通讯作者：
Sidra U. Khan;P. Hooda;M. Blackwell;R. Busquets
中科院分区：
文献类型：
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作者：
Sidra U. Khan;P. Hooda;M. Blackwell;R. Busquets
众所周知，洪水可以调动土壤中的磷（P）。然而，目前尚不清楚气候变化驱动的土壤干燥期延长，随后发生洪水，将如何影响土壤磷动态。我们在实验室条件下测试的假设，土壤前期条件（湿/干）确定洪水后动员的P量。通过淹没两种对比土壤（Dystric Cambisol [克雷登系列]和Stagni-Vertic Cambisol [Hallsworth系列]）的样品进行了一系列受控实验室实验，这些土壤均已干燥（40°C持续10天）或保持在田间水分条件下（25%水分含量）。通过在围隔生态系统中保持10 cm水柱深度来模拟洪水。定期采集水样，分析溶解活性磷（DRP），总溶解磷（TDP）和溶解非活性磷（DUP）。洪水的爆发TDP的释放与氧化还原电位的降低相一致，表明含磷铁锰矿物的还原溶解，如TDP与溶解铁之间的显著正相关性所示（r = 0.430，p < 0.001）和TDP与溶解Mn（r = 0.622，p < 0.001）。相对于潮湿的土壤，干旱土壤的洪水导致所有形式的P的溶解P浓度显著增加。这可能是由于与土壤干燥和洪水有关的因素的组合。克雷登干洪土壤在洪水后释放出更高浓度的DRP（例如，洪水后第1天为0.14 mg P L−1），这可能是由于其水和NaHCO 3可提取的P浓度高于Hallsworth干洪（HDF）土壤（洪水后第1天为0.03 mg P L−1）。然而，干洪土壤水柱中的大部分P是不反应的，HDF土壤释放出更高浓度的DUP，可能是由于其更高的有机质和微生物生物量P含量。结果表明，干旱土壤的洪水比潮湿土壤的洪水更有可能提高土壤-P的动员，因此对土壤肥力和地表水质量具有潜在的影响。
Flooding is known to mobilise soil phosphorus (P). However, it is still not clear how climate change‐driven extended periods of soil drying followed by flooding will affect soil‐P dynamics. We tested the hypothesis under laboratory conditions that soil antecedent conditions (moist/dry) determine the amount of P mobilised upon flooding. A series of controlled laboratory experiments were carried out by flooding samples of two contrasting soils (a Dystric Cambisol [Crediton series] and a Stagni‐Vertic Cambisol [Hallsworth series]), which had each been either dried (40°C for 10 days) or kept at field moisture conditions (25% moisture content). Flooding was simulated by maintaining a 10‐cm water column depth in mesocosms. Periodically collected water samples were analysed for dissolved reactive P (DRP), total dissolved P (TDP) and dissolved unreactive P (DUP). The onset of flooding significantly (p < 0.001) increased dissolved concentrations of all forms of P. The release of TDP coincided with a reduction in redox potential, suggesting reductive dissolution of P bearing iron/manganese (Fe/Mn) minerals as indicated by a significant positive correlation between TDP and dissolved Fe (r = 0.430, p < 0.001) and TDP and dissolved Mn (r = 0.622, p < 0.001). Flooding of the dried soils caused a significantly greater increase in the dissolved P concentrations of all forms of P relative to their moist‐flooded counterparts. This could be due to a combination of factors which are associated with soil drying and flooding. The Crediton dry‐flooded soils released higher concentrations of DRP upon flooding (e.g. 0.14 mg P L−1 on day 1 after flooding) perhaps due to its higher concentrations of water‐ and NaHCO3‐extractable P than the Hallsworth dry‐flooded (HDF) soil (0.03 mg P L−1 on day 1 after flooding). However, most of the P in the water column of the dry‐flooded soils was unreactive, with the HDF soil releasing higher concentrations of DUP, likely due to its higher organic matter and microbial biomass P contents. The results suggest that flooding of dried soils has greater potential to enhance mobilisation of soil‐P than flooding of moist soils and thus has potential implications for soil fertility and surface water quality.