| Response of soil organic carbon mineralization to ammonium-N addition in paddy soils with different cultivation durations in Nanniwan, Northern Shaanxi |
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| DOI：10.7606/j.issn.1000-7601.2026.03.12 |
| Key Words: paddy soil planting years ammonium nitrogen organic carbon mineralization soil carbon cycle |
| Author Name | Affiliation | | ZHOU Hanbing | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China | | YANG Fan | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China | | ZHAO Manxing | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China
Shaanxi Key Laboratory of Research and Utilization of Resource Plants on the Loess Pateau, Yan’an, Shaanxi 716000, China
Key Laboratory of Applied Ecology of Loess Plateau in Shaanxi Higher Education Institutions,Yan’an, Shaanxi 716000, China | | LI Shuo | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China | | MA Danni | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China | | WANG Xin | College of Life Sciences, Yan’an University, Yan’an, Shaanxi 716000, China |
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| Abstract: |
| To investigate the response of soil organic carbon (SOC) mineralization to ammonium-N addition in paddy soils with different cultivation durations in Nanniwan, Northern Shaanxi, and to optimize regional farmland carbon cycle management and fertilization strategies, a laboratory incubation experiment was conducted. Soil samples were collected from paddy fields with cultivation histories of 3 a, 30 a, and 78 a, together with an adjacent dryland maize field as a control. Four ammonium-N addition levels (0, 50, 100, and 150 mg·kg-1) were applied to examine SOC mineralization characteristics. The results showed that long\|term rice cultivation significantly enhanced the SOC mineralization potential. The average potential mineralization amount (C0) in the 0-20 cm layer of the 78 a paddy soil reached 2 835.97 mg·kg-1, which was 37.5% higher than that in the maize soil. Ammonium-N addition exhibited a “promotive at low\|to\|medium levels but inhibitory at high levels”effect: additions of 50-100 mg· kg-1promoted SOC mineralization in the maize soil, 3 a paddy soil, and 78 a paddy soil, with the 3 a paddy soil showing a 19.02% increase under 50 mg·kg-1 compared to the control. In contrast, the 150 mg·kg-1 treatment significantly inhibited mineralization (P<0.05), reducing the cumulative mineralization in the 0-20 cm layer of the 30 a paddy soil by 35.52% relative to the control, and that of the 78 a paddy soil by 41.21% compared to the 50 mg·kg-1 treatment. The cumulative mineralization in the 0-20 cm layer was on average 1.26 times that in the 20-40 cm layer. Correlation analysis indicated that in the 0-20 cm layer, C0 was significantly positively correlated with active carbon fractions such as microbial biomass carbon and dissolved organic carbon (P<0.01), whereas the correlations were weaker in the 20-40 cm layer. In conclusion, long\|term rice cultivation markedly elevates the SOC mineralization potential of soil, and exogenous ammonium-N promotes mineralization at low\|to\|medium concentrations (50-100 mg·kg-1) but suppresses it at a high concentration (150 mg·kg-1). |
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