Original research article
Purpose: Biochar–urea co-application can modify soil nitrogen (N) dynamics, but responses may vary with biochar feedstock, application rate, and soil properties. A laboratory incubation experiment was conducted to evaluate the effects of biochar feedstock and application rate on inorganic N dynamics under urea fertilization (200 mg N kg-1) in three Jeju volcanic ash soils differing in soil organic matter (SOM) content and associated physicochemical properties.
Methods: Two plant-residue biochars derived from Satsuma mandarin pruning branches (CB) and garlic stalks (BG) and one manure biochar derived from chicken manure (CMB) were applied at 0.2%, 0.4%, and 0.8% (w/w) to three soils with SOM contents of 12, 66, and 134 g kg-1 (LSOM, MSOM, and HSOM, respectively). First-order kinetic modeling was used to estimate the apparent net inorganic N accumulation potential (N0) and apparent rate constant (k), while fixed-interval regression was used to estimate net NH4+-N disappearance and net NO3‒-N production rates.
Results: The estimated N0 and k values differed among the three soils and varied with biochar feedstock and application rate. Relative to the urea-only treatment, most biochar treatments increased N0 in LSOM and HSOM, whereas all biochar treatments reduced N0 in MSOM. In LSOM, 0.8% CB and 0.8% GB showed lower N0 values than the urea-only treatment, while the lowest N0 in HSOM was observed under 0.2% CMB. The k values also varied among soils and treatments, indicating differences in the rate at which apparent net inorganic N accumulation approached N0. Fixed-interval analyses showed that net NH4+-N disappearance was more responsive to biochar treatments than net NO3‒-N production. The distinct responses of CMB may partly reflect its substantially higher water-extractable inorganic N content compared with the plant-residue biochars.
Conclusions: Overall, inorganic N dynamics under urea fertilization differed markedly among the three Jeju volcanic ash soils, which varied in SOM content and associated physicochemical properties. Biochar–urea co-application modified net NH4+-N disappearance, net NO3‒-N production, and apparent net inorganic N accumulation, but the magnitude and direction of these responses varied with biochar feedstock, application rate, and soil physicochemical properties.
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10.1016/j.soilbio.2020.108011- Publisher :Korean Society of Soil Science and Fertilizer
- Publisher(Ko) :한국토양비료학회
- Journal Title :Korean Journal of Soil Science and Fertilizer
- Journal Title(Ko) :한국토양비료학회 학회지
- Volume : 59
- No :3
- Pages :217-231
- Received Date : 2026-03-17
- Revised Date : 2026-08-19
- Accepted Date : 2026-08-20
- DOI :https://doi.org/10.7745/KJSSF.2026.59.3.217
Korean Journal of Soil Science and Fertilizer
