ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Nutrition
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1668092
Depth-dependent effects of crop rotation and monoculture on dissolved organic matter quantity and quality
Provisionally accepted
- Institute of Soil Science and Plant Cultivation, Puławy, Poland
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Soil dissolved organic matter (DOM) plays a crucial role in terrestrial biogeochemical processes, regulating nutrient cycling and carbon sequestration. However, how agricultural practices such as crop rotation and monoculture influence the vertical distribution and molecular traits of DOM remains unclear. This study was conducted within a long-term field experiment established in 1994 at the Agricultural Experimental Station (IUNG-PIB) in Osiny, eastern Poland. The experiment compared two contrasting cropping systems: a three-year rotation (winter oilseed rape–winter wheat–spring barley) and continuous monoculture of winter wheat. Soil samples were collected from three depths (0–30, 30–60, and 60–90 cm) to examine the concentrations and spectroscopic properties of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP). DOM concentrations decreased significantly with depth (P < 0.001), with no major differences between cropping systems except for higher DOC in the 60–90 cm layer under monoculture (P < 0.05). UV–Vis spectroscopy showed increased SUVA280 and decreased E4/E6 ratios with depth, indicating progressive molecular condensation and humification of DOM. These patterns were consistent across cropping systems, highlighting soil depth as the dominant factor controlling DOM quality. Key environmental drivers of DOM variability included soil organic carbon, total nitrogen, humus content, available phosphorus, and soil depth. Variable importance analysis indicated that DOC was primarily influenced by total nitrogen, total carbon, and DOP; DON was governed by DOC, soil depth, and available phosphorus; and DOP was shaped by humus, total phosphorus, and available phosphorus. Overall, this study demonstrates depth-dependent differentiation of DOM fractions in agricultural soils and shows that management effects are limited to deeper layers. These findings provide mechanistic insights for optimizing cropping systems and enhancing nutrient cycling and carbon sequestration, particularly in subsoils that act as long-term carbon reservoirs.
Keywords: Carbon-nitrogen-phosphorus interactions, Soil dissolved organic matter (DOM), agricultural management, deep soil carbon stabilization, spectroscopic characterization
Received: 17 Jul 2025; Accepted: 31 Jul 2025.
Copyright: © 2025 Ren, Debaene, Ukalska-Jaruga and Smreczak. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Tianjing Ren Ren, Institute of Soil Science and Plant Cultivation, Puławy, Poland
Bozena Smreczak, Institute of Soil Science and Plant Cultivation, Puławy, Poland
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