| 摘 要： |
Background and aimsDissolved organic matter (DOM) stands out as a highly active component within the organic matter pool. It is hypothesized to play a crucial role by adsorbing onto minerals and serving as a precursor for soil aggregates. However, the impact of DOM substrate types and addition levels on the intricate dynamics of soil aggregates remains elusive.MethodsA 28-day short-term incubation experiment was conducted to investigate the responses of a Japanese Andisol to different DOM substrates, exploring the influence of three DOM substrates and two concentration levels. REOs concentrations in three aggregate fractions were measured on 0, 7, 14, and 28 days of incubation to calculate the aggregates transformation paths and relative aggregate change.ResultsDOM addition significantly increased aggregate stability in Andisols soil, evident in the elevated mean weight diameter (MWD) compared to the control (CK) treatment. The change of aggregate stability during incubation is determined by both DOM types and addition levels. The N-Acetyl-D( +)-Glucosamine (NADG) treatment, peaking at 14 days, whereas the vanillin (VAN) treatment reaching the highest MWD value before incubation (0 days). The increase in aggregate stability was reflected in the transformation paths of aggregates. NADG treatment, VAN treatment, and the NADG&VAN (MIX) mixture all contributed to reduced macroaggregate breakdown and inhibited the microaggregates breakdown. Furthermore, the relative changes in aggregate turnover exhibited varying trends across treatments. Regarding macroaggregate dynamics, the addition of vanillin, especially in the 100%VAN and 100%MIX treatments, significantly enhanced macroaggregate formation, with an increase of over 30% in the 100%MIX treatment after 28 days. Microaggregate dynamics varied among treatments. In the 100%NADG and 100%VAN treatments, there was an initial increase from 0 to 7 days, succeeded by a decrease from 7 to 28 days. The 50%VAN and 50%MIX treatments exhibited an increasing trend from 0 to 14 days, followed by a decrease from 14 to 28 days.ConclusionOverall, these findings highlight the important role of DOM in aggregate dynamics and suggest that the types and addition levels of DOM can significantly impact soil aggregate turnover pathways. |
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