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Shifts in Dissolved Organic Matter and Microbial Communities Under Continuous Cropping of Aralia continentalis Kitag.: A Comparative Study of 2-, 6-, and 12-Year Durations
by
Qian Liu
1,2,*, 
Xingchi Guo
1,
Ying Qu
1,
Yuhe Xing
1,
Junyan Zheng
1,
Zhiyu Dong
1,
Wei Yu
1 and
Guoyu Zhang
1 1
College of Landscape Architecture, Changchun 130012, China
2
Institute of Resource Utilization and Soil Conservation, Changchun University, Changchun 130022, China
*
Author to whom correspondence should be addressed.
Biology 2025, 14(12), 1750; https://doi.org/10.3390/biology14121750 (registering DOI)
Submission received: 28 October 2025
/
Revised: 30 November 2025
/
Accepted: 4 December 2025
/
Published: 6 December 2025
Simple Summary
Continuous cropping can affect soil health, which is vital for growing crops sustainably. In this study, we looked at how growing Aralia continentalis Kitag. for 2, 6, and 12 years affects the soil around its roots. We found that over time, the soil health declined, particularly in terms of important nutrients and organic matter. Initially, the microbial diversity in the soil increased, but after 6 years, it stabilized. As the soil became poorer in nutrients, the types of microbes changed, with those needing fewer nutrients becoming more common. We also used UV-visible spectroscopy, 3D fluorescence spectroscopy, and Partial Least Squares Path Modeling (PLS-PM) to quantify the relationships between soil nutrients, microbes, and organic matter are related. We found that the more organic matter in the soil, the more diverse the microbes were. Additionally, UV-visible and 3D fluorescence spectroscopy showed that measuring the light absorbed by the soil could help us track the health of the soil and its microbes. These findings help us understand the long-term effects of continuous cropping and can guide farmers in using better practices to keep soil healthy, which is essential for sustainable farming.
Abstract
Continuous cropping affects soil health, microbial diversity, and organic matter dynamics, but its long-term impacts on soils under Aralia continentalis Kitag. (a medicinally important Northeast China-native plant) remain unclear. This study evaluated effects of 2-, 6-, and 12-year continuous cropping on soil microbial communities, physicochemical properties, and dissolved organic matter (DOM) of bulk soils, and elucidated links between cropping duration and soil health indicators. Results showed that key physicochemical properties (total organic carbon, TOC) and available nutrients (available nitrogen, AN; available phosphorus, AP; available potassium, AK) declined with cropping duration: AN, AP, and AK decreased from 75.24 ± 1.2, 16.39 ± 0.05, and 104.8 ± 0.27 mg·kg−1 (2 years) to 63.47 ± 1.53, 13.38 ± 0.16, and 88.71 ± 0.94 mg·kg−1 (12 years), respectively. Microbial diversity increased initially but stabilized after 6 years, with communities shifting from copiotrophic taxa (e.g., Proteobacteria) to oligotrophic taxa (e.g., Acidobacteria). Partial Least Squares Path Modeling (PLS-PM) revealed strong positive correlations between dissolved/organic carbon (DOC/TOC) and microbial diversity, highlighting organic matter’s role in sustaining microbial richness. UV-visible and 3D fluorescence spectroscopy indices correlated significantly with microbial diversity, confirming their utility for monitoring DOM quality and microbial dynamics. This study clarifies dynamic interactions between soil properties, microbial diversity, and organic matter under continuous cropping, providing insights for sustainable cultivation of A. continentalis.
