Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
Sci Rep. 2018 Jan 11;8(1):444. doi: 10.1038/s41598-017-18963-x.
Dynamic changes in Fe oxides and magnetic properties during natural pedogenesis are well documented, but variations and controls of Fe and magnetism changes during anthropedogenesis of paddy soils strongly affected by human activities remain poorly understood. We investigated temporal changes in different Fe pools and magnetic parameters in soil profiles from two contrasting paddy soil chronosequences developed on calcareous marine sediment and acid Quaternary red clay in Southern China to understand the directions, phases and rates of Fe and magnetism evolution in Anthrosols. Results showed that paddy soil evolution under the influence of artificial submergence and drainage caused changes in soil moisture regimes and redox conditions with both time and depth that controlled Fe transport and redistribution, leading to increasing profile differentiation of Fe oxides, rapid decrease of magnetic parameters, and formation of diagnostic horizons and features, irrespective of the different parent materials. However, the initial parent material characteristics (pH, Fe content and composition, weathering degree and landscape positions) exerted a strong influence on the rates and trajectories of Fe oxides evolution as well as the phases and rates of magnetism changes. This influence diminished with time as prolonged rice cultivation drove paddy soil evolving to common pedogenic features.
自然成土过程中氧化铁和磁性的动态变化已有大量记载，但人类活动强烈影响的水稻土人为成土过程中氧化铁和磁性的变化及其控制因素仍知之甚少。我们研究了中国南方在钙质海洋沉积物和第四纪酸性红黏土上发育的两个对比水稻土时间序列土壤剖面中不同铁库和磁性参数的时间变化，以了解人为土壤中铁和磁性演化的方向、阶段和速率。结果表明，人工淹水和排水的影响导致土壤水分状况和氧化还原条件随时间和深度发生变化，控制了铁的输运和再分配，导致氧化铁的剖面分异增加，磁性参数迅速下降，并形成了诊断层和特征，而与不同的母质无关。然而，初始母质特征（pH 值、铁含量和组成、风化程度和景观位置）对氧化铁演化的速率和轨迹以及磁性变化的阶段和速率有很强的影响。随着水稻种植时间的延长，水稻土逐渐演化为常见的成土特征，这种影响会随着时间的推移而减弱。
