How silicon affects phosphate availability and carbon turnover in soils

磷（P）是生命结构和代谢途径的关键元素。磷是作物初级生产和产量的最大限制元素之一，导致全球范围内农业中大量使用磷肥。尽管土壤的全磷含量不是特别低，但很大一部分以植物不可利用的形式储存，如有机磷，或根据土壤pH值结合/吸附到Al-Fe或Ca矿物上。在保持产量不变的前提下减少磷肥施用量是未来农业面临的主要挑战之一。2最近的研究表明，最高的磷有效性与硅酸盐结合磷的最高份额相一致。因此，我们的目标是解开的重要性，土壤中的有效硅（Si）的铝和铁（氢）氧化物和钙矿物的结合位点的P动员的矿物和土壤的大范围内的不同绑定形式的P在拟议的项目。硅的可用性在土壤和沉积物中变化至少两个数量级，范围从0.01到2.0毫米。最近的研究还表明，硅影响土壤中的磷的可用性和土壤呼吸的潜力。我们的初步研究结果表明，硅在泥炭中的碳周转率的机制，其中Si动员P从铁结合位点的潜在的巨大影响。这表明一个新的，但几乎未研究的联系硅和C-循环，是潜在的重要全球C营业额。最重要的是，拟议的项目：第一个结果显示，在泥炭土壤中的CO2和CH 4浓度增加硅的可用性显着增加。我们还发现了一个强大的增加P和溶解有机碳（DOC）动员孔隙水增加硅的可用性。进一步的分析表明，硅干扰了土壤中存在的铁相，并可能影响这些铁相的磷酸盐结合。本研究的目的是解开（i）增加硅的有效性是否会导致磷从矿物结合位点的动员，从而增加磷的有效性，以及在何种程度上，（ii）与磷和碳相比，硅对土壤矿物结合位点的亲和力更高，（iii）较高的硅有效性将促进有机质的矿化，这是由于增加了磷的有效性，导致C的活化（即增加DOC）从结合位点，和（iv）硅会干扰P的有效性在土壤pH值范围从4到8。了解硅如何干扰磷的可用性是一个潜在的工具，以减少农业需要磷肥的最佳磷供应。

Phosphorus (P) is a key element for life's structure and metabolic pathways. Phosphorus is one of the most limiting elements for primary production and yield of crop plants, resulting in the use of large amounts of P fertilizers in agriculture at the global scale. Whereas the total P content of soils is not particularly low, a large fraction is stored in plant unavailable form like organic phosphorus, or is bound/adsorbed to Al-Fe or Ca minerals depending on soil pH. Due to limited resources, reducing P fertilization at constant yield is one of the main challenges for agriculture in future.Recent studies indicate that the highest P availability coincides with highest share of silicate bound P. Thus, we aim to disentangle the importance of available silicon (Si) in soils for mobilization of P from the binding sites of Al and Fe (hydr)oxides and Ca minerals for a large range of minerals and soils with different binding forms of P in the proposed project. Si availability varies over at least two orders of magnitude in soils and sediments, ranging from 0.01 to 2.0 mM. Recent research also suggests the potential of Si affecting P availability in soils and respiration in soils. Our preliminary results indicate a potentially large effect of Si availability in peat on carbon turnover rates by a mechanism wherein Si mobilizes P from Fe binding sites. This indicates a new but nearly unstudied link between Si and C-cycling that is potentially important for global C turnover. Most importantly for the proposed project: first results revealed a significant increase of CO2 and CH4 concentrations in peat soils under increased Si availability. We also found a strong increase of P and dissolved organic carbon (DOC) mobilization to pore water by increased Si availability. Further analysis indicated that Si interferes with the Fe-phases present in the soil and possibly influences phosphate binding by these Fe-phases. The aim of the proposed study is to disentangle whether and to which extend (i) increased Si availability will lead to mobilization of P from mineral binding sites and therefore increases P availability, (ii) Si has higher affinity for binding sites of soil mineral as compared to P and C, (iii) higher Si availability will enhance the mineralization of organic matter due to increasing P availability resulting in mobilization of C (i.e. increased DOC) from the binding sites, and (iv) Si will interfere with P availability at the soil pH range from 4 to 8. Understanding how Si interferes with P availability is a potential tool to reduce the agricultural need for P fertilizer for optimal P supply.