How silicon affects phosphate availability and carbon turnover in soils

硅如何影响土壤中磷酸盐的有效性和碳周转

• 批准号: 418126534
• 负责人: Professor Dr. Karsten Kalbitz
• 金额: --
• 依托单位: Institut für Bodenkunde und Standortslehre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/418126534?language=en
• 关键词: How; silicon; affects; phosphate; availability

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.

磷（P）是生命结构和代谢途径的关键元素。磷是农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使用大量磷肥。虽然土壤的总磷含量并不是特别低，但很大一部分以植物无法利用的形式储存，如有机磷，或者根据土壤 pH 值结合/吸附到铝铁或钙矿物质上。由于资源有限，在恒定产量下减少磷施肥是未来农业面临的主要挑战之一。最近的研究表明，最高的磷利用率与硅酸盐结合磷的最高比例相一致。因此，我们的目标是阐明土壤中有效硅（Si）对于从铝和铁（氢氧化）氧化物以及钙矿物的结合位点移动磷的重要性，对于具有不同结合力的多种矿物质和土壤 拟议项目中 P 的形式。土壤和沉积物中硅的可用性变化至少两个数量级，范围为 0.01 至 2.0 mM。最近的研究还表明，硅可能影响土壤中磷的有效性和土壤呼吸。我们的初步结果表明，泥炭中硅的有效性对碳周转率具有潜在的巨大影响，其机制是硅从铁结合位点动员磷。这表明硅和碳循环之间存在一种新的但几乎未经研究的联系，这对全球碳周转可能很重要。对于拟议项目最重要的是：初步结果显示，在硅利用率增加的情况下，泥炭土中的二氧化碳和甲烷浓度显着增加。我们还发现，通过增加硅的利用率，磷和溶解有机碳 (DOC) 向孔隙水中的迁移量显着增加。进一步分析表明，Si 会干扰土壤中存在的 Fe 相，并可能影响这些 Fe 相与磷酸盐的结合。拟议研究的目的是阐明是否以及在多大程度上（i）增加的硅有效性将导致磷从矿物结合位点的动员，从而增加磷的有效性，（ii）与磷和碳相比，硅对土壤矿物质的结合位点具有更高的亲和力，（iii）更高的硅有效性将增强有机质的矿化，因为增加的磷有效性导致从矿物结合位点动员碳（即增加DOC）。 (iv) 在土壤 pH 值范围为 4 至 8 的情况下，硅会干扰磷的有效性。了解硅如何干扰磷的有效性是减少农业对磷肥的需求以实现最佳磷供应的潜在工具。