基于同步辐射红外光谱技术的江苏茶园土壤矿物—有机复合体固存研究

Sequestration study on mineral-organic complex of Jiangsu tea garden soil with synchrotron radiation infrared micro-imaging

  • 摘要: 【目的】分析江苏省不同茶区土壤结构的差异,寻求差异化的养分管理途径,为全省实施茶园化肥减施增效提供科学参考。【方法】表征江苏代表性茶园土壤矿物—有机复合体特征结构,利用同步辐射红外显微成像法对茶园土壤团聚体切片进行化学成像,从而获得特定组分的空间分布,进而从原位上表征样品中矿物和有机官能团的分布特征,探索茶园土壤有机碳的稳定机制。【结果】江苏省茶园土壤团聚体中的有机碳以脂肪碳(2881 cm-1)、芳香碳(1620 cm-1)和多糖碳(1100 cm-1)等形态存在,同时还有矿质元素氧化物Fe-O、Al-O、Si-O等存在。茶园土壤微团聚体中各元素空间分布具有高度异质性,甲基和亚甲基C-H等脂肪碳较集中地吸附在土壤微团聚体边缘(也有少量的矿物存在),而铁铝矿物的Al-O、Fe-O等官能团聚集在微团聚体内部核心位置,同时表面也吸附少量有机质; 87.5%茶园土壤中黏土矿物(3620 cm-1)与脂肪碳相关性最高,施肥措施和植茶年限影响矿物—有机官能团相关性排序; 75.0%茶园土壤铁氧化物与多糖碳相关性最高,各茶园土壤中铁铝矿物与有机官能团的亲和性排序规律受海拔、pH和植茶年限等影响而存在差异。【结论】江苏不同茶区土壤团聚体及其有机碳的分布特征揭示土壤团聚体通过矿物—有机复合体将有机质留存于土壤中,提高土壤有机质含量。生产中宜依据不同茶区养分具体管理方式、茶叶栽培特点及土壤条件,因地制宜采取差异化的茶园养分管理策略。

     

    Abstract: 【Objective】To analyze the differences between soil structures of various tea gardens in Jiangsu for finding out management methods of nutrient requirements,so as to provide scientific basis for reducing usage of chemical fertilizer while enhancing effect.【Method】To characterize structure of mineral-organic complex of tea garden soil in Jiangsu, Jiangsu tea garden soil microaggregates were sliced and analyzed with synchrotron radiation infrared micro-imaging to observe the distribution of specific components,and the distribution of mineral and organic functional groups in the samples were characterized in situ to explore mechanisms of stabilizing organic carbon in tea garden soil.【Result】Results showed that organic carbon existed in the forms of larger molecular organics(i.e. aliphatic-C, 2881 cm-1, aromatic-C, 1620 cm-1, and polysaccharides-C, 1100 cm-1) and mineral element oxides Fe-O, Al-O, Si-O groups were found in all soils. The spatial distributions of each element in soil microaggregates in tea gardens were highly heterogeneous. Aliphatic carbons such as methyl and methylene C-H were adsorbed on the edge of soil microaggregates(a small amount of minerals was also found there),while functional groups such as Al-O and Fe-O of iron and aluminum minerals gathered at the core of microaggregates,and a small amount of organic material was also absorbed on the surface of microaggregates. Clay minerals (3620 cm-1) had the highest correlation with aliphatic-C in 87.5% tea garden soil and fertilization and tea planting years affected the order of mineral organic functional group correlation. The correlation between iron oxide and polysaccharides-C was the highest in 75.0% tea garden soil and the affinity order of Fe/Al minerals and organic functional groups in each type tea garden soil was different due to the influence of altitude, pH and planting years. In summary, synchrotron-radiation-based infrared spectro microscopy is expected to be a new method to characterize soil fertility of tea garden.【Conclusion】The distribution pattern of microaggregates and organic carbon in soil from different tea gardens in Jiangsu reveals that through mineral-organic complex,organic material is kept in soil by soil microaggregates to increase content of soil organic material. In the process of tea production,different nutrient management strategies should be taken according to different situations of concrete nutrient management,tea cultivation and soil condition.

     

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