Alfalfa fields with different stand ages alters soil inorganic nitrogen dynamics through shifts in nitrogen-cycling functional genes across growth stages
- 1Institute of Pastoral Hydraulic Research, Ministry of Water Resources (IPHR-MWR) , ,
Abstract
Introduction: Alfalfa cultivation is associated with soil nitrogen availability and microbial nitrogen-cycling functional potential. However, how soil inorganic nitrogen and nitrogen-cycling functional genes vary with alfalfa stand age across growth stages remains unclear.
Methods: Using a chronosequence approach, we investigated soil inorganic nitrogen and nitrogen-cycling functional genes in a maize-field control (CK) and 2-, 3-, 4-, and 7-year-old alfalfa fields (T1–T4) during the regreening, flowering, and maturity-harvest stages. Soil NO 3 - -N and NH 4 + -N concentrations and TPM-normalized abundances of nitrogen-cycling functional genes were determined. Correlation analysis, PERMANOVA, and structural equation modeling (SEM) were used to examine their relationships.
Results: Soil NO 3 - -N and NO 4 + -N concentrations differed significantly among stand ages and generally exhibited unimodal patterns, with the highest observed values in the 4-year field (T3) and lower values in the 7-year field (T4). The abundances of genes involved in nitrification, denitrification, and nitrate reduction also varied with stand age and showed growth-stage-specific patterns. Growth stage explained a greater proportion of variation in nitrogen-cycling gene profiles than stand age, although stand age was also significantly associated with these profiles. The relationships between functional genes and soil inorganic nitrogen varied among growth stages. SEM analysis suggested that growth stage was the primary factor associated with variation in nitrogen-cycling gene groups. Nitrification-related genes were positively correlated with soil inorganic nitrogen, whereas nitrate reduction-related genes showed negative correlations.
Conclusion: Overall, the 4-year alfalfa field exhibited the highest observed soil inorganic nitrogen concentrations, while this pattern was less evident in the 7-year field. These findings indicate that soil nitrogen status and nitrogen-cycling functional genes vary jointly with alfalfa stand age and growth stage. Nitrogen-cycling functional genes may serve as potential indicators of soil nitrogen status, although further experimental studies are needed to verify these relationships.
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BibTeX
@article{tian2026alfalfa,
title = {{Alfalfa fields with different stand ages alters soil inorganic nitrogen dynamics through shifts in nitrogen-cycling functional genes across growth stages}},
author = {Delong Tian and Mingzi Lv and Guoshuai Wang and Ting Fan},
journal = {Frontiers in microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1958461},
url = {https://europepmc.org/article/PMC/PMC13672546},
note = {CC BY},
}
RIS
TY - JOUR
TI - Alfalfa fields with different stand ages alters soil inorganic nitrogen dynamics through shifts in nitrogen-cycling functional genes across growth stages
AU - Delong Tian
AU - Mingzi Lv
AU - Guoshuai Wang
AU - Ting Fan
PY - 2026
DA - 2026/10/02
JO - Frontiers in microbiology
DO - 10.3389/fmicb.2026.1958461
UR - https://europepmc.org/article/PMC/PMC13672546
AB - Introduction: Alfalfa cultivation is associated with soil nitrogen availability and microbial nitrogen-cycling functional potential. However, how soil inorganic nitrogen and nitrogen-cycling functional genes vary with alfalfa stand age across growth stages remains unclear. Methods: Using a chronosequence approach, we investigated soil inorganic nitrogen and nitrogen-cycling functional genes in a maize-field control (CK) and 2-, 3-, 4-, and 7-year-old alfalfa fields (T1–T4) during the regreening, flowering, and maturity-harvest stages. Soil NO 3 - -N and NH 4 + -N concentrations and TPM-normalized abundances of nitrogen-cycling functional genes were determined. Correlation analysis, PERMANOVA, and structural equation modeling (SEM) were used to examine their relationships. Results: Soil NO 3 - -N and NO 4 + -N concentrations differed significantly among stand ages and generally exhibited unimodal patterns, with the highest observed values in the 4-year field (T3) and lower values in the 7-year field (T4). The abundances of genes involved in nitrification, denitrification, and nitrate reduction also varied with stand age and showed growth-stage-specific patterns. Growth stage explained a greater proportion of variation in nitrogen-cycling gene profiles than stand age, although stand age was also significantly associated with these profiles. The relationships between functional genes and soil inorganic nitrogen varied among growth stages. SEM analysis suggested that growth stage was the primary factor associated with variation in nitrogen-cycling gene groups. Nitrification-related genes were positively correlated with soil inorganic nitrogen, whereas nitrate reduction-related genes showed negative correlations. Conclusion: Overall, the 4-year alfalfa field exhibited the highest observed soil inorganic nitrogen concentrations, while this pattern was less evident in the 7-year field. These findings indicate that soil nitrogen status and nitrogen-cycling functional genes vary jointly with alfalfa stand age and growth stage. Nitrogen-cycling functional genes may serve as potential indicators of soil nitrogen status, although further experimental studies are needed to verify these relationships.
SN - 1664-302X
ER -