Natural organic matter control on silicate interactions with iron oxides and silicon phytoavailability

天然有机物对硅酸盐与氧化铁相互作用和硅植物有效性的控制

• 批准号: 405548376
• 负责人: Professor Dr. Robert Mikutta
• 金额: --
• 依托单位: Professur für Bodenkunde und Bodenschutz
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405548376?language=en
• 关键词: Natural; organic; matter; control; silicate

Over the last years, the importance of silicon (Si) for plant nutrition, especially for rice, has been increasingly recognized. Uptake of Si enhances biomass yields and stress tolerance against pathogens. Silicon is released by weathering of primary and secondary minerals. Pedogenic Fe oxides, likewise formed during weathering, are important sorbents of silicic acid (H4SiO4), and thus, potentially control plant-available Si. While the basic mechanisms of H4SiO4 sorption to Fe oxides are relatively well understood, possible effects of natural organic matter (OM), despite being abundant in all soils, did not receive much attention. The effects of sorption competition with dissolved OM or due organic coatings on mineral surfaces on the retention of H4SiO4 by Fe oxide phases are largely unknown. Consequently, the influence of OM on the phytoavailability of Si is poorly understood. Particularly in soils with strongly contrasting redox conditions, as in submerged rice cropping, little research has been conducted regarding the interactions among Fe oxides, Si and OM. Our project will, therefore, test for the first time the effects of natural OM on the Si retention by Fe oxides and the consequences for the phytoavailability of Si. Based on batch experiments under different environmental conditions, we will first study the adsorption and desorption of H4SiO4 in presence of OM and the impact of OM on the surface Si speciation (monomeric to polymeric Si) by relying on surface-sensitive X-ray photoelectron spectroscopy (XPS). We will study the consequences of the Si binding to Fe oxides in presence of OM for the Si uptake by rice plants in subsequent micro- and mesocosm experiments. Microcosm experiments will be conducted with defined Si-Fe oxide phases in order to test whether and to which extent Fe oxide-bound Si can be utilized by plants, with special consideration to the role of OM and the prevailing Si surface species. In mesocosms with natural soil, we will elucidate these processes under variable redox conditions by determining the release / immobilization of Si, the changes in Si surface species, and the plant uptake. The results of these experiments will promote our understanding of the impact of natural OM on the Si cycling in soils.

近年来，硅对植物营养的重要性，特别是对水稻的重要性越来越受到人们的重视。Si的吸收提高了生物量产量和对病原体的胁迫耐受性。硅是通过原生和次生矿物的风化作用释放出来的。成土铁氧化物，同样形成在风化过程中，是重要的吸附剂的草酸（H4 SiO 4），因此，潜在地控制植物有效硅。虽然H4 SiO 4吸附铁氧化物的基本机制是比较好的理解，可能的影响，天然有机质（OM），尽管在所有土壤中丰富，没有得到太多的关注。与溶解的OM或由于有机涂层矿物表面上的保留H4 SiO 4的Fe氧化物相的吸附竞争的影响在很大程度上是未知的。因此，OM对硅的植物有效性的影响知之甚少。特别是在土壤中强烈对比的氧化还原条件下，在沉水水稻，很少有研究已经进行了关于铁氧化物，硅和OM之间的相互作用。因此，我们的项目将首次测试天然OM对Fe氧化物对Si保留的影响以及Si的植物有效性的后果。基于不同环境条件下的批量实验，我们将首先研究在OM存在下H4 SiO 4的吸附和脱附以及OM对表面Si形态（单体Si到聚合Si）的影响，依靠表面敏感的X射线光电子能谱（XPS）。我们将在随后的微生态系统和围隔生态系统实验中研究有机质存在下硅与铁氧化物结合对水稻吸收硅的影响。微观实验将进行定义的Si-Fe氧化物相，以测试是否以及在何种程度上可以利用铁氧化物结合的硅的植物，特别考虑OM和占主导地位的硅表面物种的作用。在与自然土壤的围隔生态系统中，我们将阐明这些过程在可变的氧化还原条件下，通过确定释放/固定的硅，硅表面物种的变化，和植物吸收。这些实验结果将促进我们对土壤中天然有机质对硅循环影响的认识。