Peatlands are globally important sinks and sources for greenhouse gasses. Their carbon (C) balances are dependent on input of biomass, its quality and decomposition. Silicon (Si) is known to influence the C quality, especially of graminoids, and it influences decomposition under oxic conditions. Drying – rewetting events (D/W), which may influence C mineralization and change nutrient availability, have been predicted to increase in frequency. This raises the question if effects of Si on decomposition are modified by such D/W events.

To elucidate this question, we conducted a study with mesocosms extracted from a fen peatland.

We hypothesized, that (I, II) there would be higher gas and solute concentrations after Si addition compared to the control after D/W. Further we expected (III) that higher respiratory fluxes of CO₂ and CH₄ would occur after Si addition and D/W and that (IV) there would be a higher gross primary production (GPP) under Si addition due to more viable biomass that is less prone to drought effects. Finally we hypothesized that (V) the chemical composition of Carex rostrata Stokes leaves grown under Si fertilization after a D/W cycle would be less recalcitrant compared to of C. rostrata leaves from the controls. To test these hypotheses, a control and a Si treatment group of mesocosms were subjected to a controlled D/W cycle. We measured soil gas (DIC and CH₄), and solute concentrations (P, Si, Fe and TOC) and gas fluxes of CO₂ and CH₄. Furthermore, we characterized the graminoid biomass for major element contents and by infrared spectroscopy (FTIR) for organic matter quality.

Higher CH₄ fluxes were observed in the Si fertilized mesocosms. There was no difference between the treatments in the ER CO₂ fluxes, whereas the NEE and GPP fluxes indicated higher CO₂ uptake in the Si treated mesocosms. Solute concentrations showed no differences, neither for dissolved gasses , nor for solutes. C. rostrata leaves had lower shares of lignin, waxes, fats, and phenols in plants from the Si fertilized mesocosms.

We concluded, that during D/W, plants from Si fertilized mesocosms accumulated more Si than plants from the control mesocosms. These plants were more viable, produced potentially more exudates and had more readily decomposable litter than controls, due to their lower share in recalcitrant moieties. This may have stimulated CH₄ production and emission of CH₄ from the soil into the atmosphere through abundant aerenchyma roots, bypassing oxic, methanotrophic peat layers.

泥炭地是全球重要的温室气体汇和来源。它们的碳 (C) 平衡取决于生物质的输入、其质量和分解。众所周知，硅 (Si) 会影响碳质量，尤其是禾本科植物的碳质量，并且会影响有氧条件下的分解。干燥 - 再润湿事件 (D/W) 可能会影响 C 矿化和改变养分可用性，预计会增加频率。这提出了这样的 D/W 事件是否会改变 Si 对分解的影响的问题。

为了阐明这个问题，我们对从泥炭地中提取的中胚层进行了一项研究。

我们假设，与 D/W 后的对照相比，(I, II) 添加 Si 后会有更高的气体和溶质浓度。此外，我们预计 (III)在添加 Si 和 D/W 后会出现更高的 CO ₂和 CH ₄呼吸通量，并且 (IV) 在添加 Si 下会出现更高的总初级生产 (GPP)，这是由于更可行的生物量不易受干旱影响。最后，我们假设 (V)与C. rostrata相比，在 D/W 循环后在 Si 施肥下生长的Carex rostrata Stokes 叶子的化学成分将不那么顽固离开控件。为了检验这些假设，中胚层的对照和硅处理组进行了受控的 D/W 循环。我们测量了土壤气体（DIC 和 CH ₄）、溶质浓度（P、Si、Fe 和 TOC）以及 CO ₂和 CH _{4 的}气体通量。此外，我们表征了禾本科生物量的主要元素含量，并通过红外光谱 (FTIR) 表征了有机质质量。

在受硅施肥的中宇宙中观察到更高的 CH ₄通量。ER CO ₂通量的处理之间没有差异，而NEE 和GPP 通量表明Si 处理的中层生物体中CO ₂吸收更高。溶质浓度没有显示出差异，无论是溶解气体还是溶质。C. rostrata叶子在来自 Si 受精中层的植物中的木质素、蜡、脂肪和酚类含量较低。

我们得出的结论是，在 D/W 期间，Si 受精中层的植物比对照中层的植物积累了更多的 Si。由于它们在顽固部分中的份额较低，这些植物比对照更能存活，产生更多的渗出物，并且具有更容易分解的凋落物。这可能刺激了 CH _{4 的}产生和 CH ₄从土壤中通过丰富的通气组织根部排放到大气中，绕过了好氧、甲烷营养的泥炭层。