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首页> 外文期刊>Canadian Water Resources Journal >Potential phosphorus mobilization from above-soil winter vegetation assessed from laboratory water extractions following freeze-thaw cycles
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Potential phosphorus mobilization from above-soil winter vegetation assessed from laboratory water extractions following freeze-thaw cycles

机译：冻融循环后实验室抽水对土壤上方冬季植被中潜在的磷动员的影响

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摘要

Maintaining crop residue or cover crops on fields during winter is a recommended beneficial management practice (BMP). However, losses of dissolved reactive phosphorus (DRP) to runoff have been attributed to vegetation following freeze-thaw cycles (FTC). Using a factorial design in the laboratory, this study investigated the potential influence of four FTC types at -4 to + 4 degrees C (frozen, frozen and thawed 1x, frozen and thawed 5x, frozen and thawed 5x with extraction after each thaw) and one control (never frozen) on DRP loss from the residue of Triticum aestivum ( winter wheat) and from two cover crops, Trifolium pretense (red clover) and Avena sativa (oat). DRP losses were measured using three different water extraction techniques: a traditional laboratory determination of water extractable P (WEP), a modified water extraction intended to simulate a rainfall event, and a modified water extraction intended to simulate surface ponding. Both cover crops released more DRP than winter wheat residue did under all treatments, suggesting that winter wheat residues pose little risk for DRP release during the non-growing season (NGS). Of the two cover crops studied, oat was more sensitive to FTC and may therefore pose a greater risk of late autumn/winter DRP loss in comparison to red clover, which is often terminated in early fall. Water extraction technique was also found to be important, as simulated surface ponding extracted more DRP than simulated rainfall did for all three plant types. These results suggest that both cover crop species and placement in the landscape can be optimized to reduce P release from above-ground vegetation in winter. The use of cover crops in sections of fields that are prone to flooding following large events such as snowmelt should be avoided. Field studies are needed to further examine the rates and timing of potential and actual losses of DRP from above-ground vegetation in winter.
机译：建议在冬季保持作物残渣或在田间覆盖作物，这是一项有益的有益管理措施（BMP）。然而，融化后的活性磷（DRP）因径流损失而归因于冻融循环（FTC）后的植被。在实验室中使用析因设计，本研究调查了在-4至+ 4摄氏度下四种FTC类型（冷冻，冷冻和解冻1x，冷冻和解冻5x，冷冻和解冻5x，每次解冻后提取5x）的潜在影响，以及一个对照（从未冷冻过）来自普通小麦（冬小麦）残留物和两个有盖作物三叶草（红三叶草）和燕麦（燕麦）的DRP损失。使用三种不同的水提取技术来测量DRP损失：传统的实验室测定可提取水的P（WEP），旨在模拟降雨事件的改良水提取方法和旨在模拟地表淤积的改良水提取方法。在所有处理下，两种覆盖作物释放的DRP都高于冬小麦残留，这说明在非生长季节（NGS），冬小麦残留几乎没有释放DRP的风险。在所研究的两种覆盖作物中，燕麦对FTC更加敏感，因此与红三叶草相比，燕麦对秋冬DRP损失的风险更大，红三叶草通常在初秋时终止。还发现水提取技术很重要，因为对于所有三种植物，模拟地表池塘提取的DRP比模拟降雨要多。这些结果表明，冬季可以优化覆盖作物种类和在景观中的位置，以减少地上植被的磷释放。应避免在诸如融雪之类的大事件后容易泛滥的田间使用覆盖作物。需要进行实地研究，以进一步检查冬季地面植被中DRP潜在损失和实际损失的速度和时间。

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