Summary
This controlled incubation study examined how 1% biochar incorporation affects soil nitrogen cycling in acidic red soil from pomelo orchards across a range of pH conditions. The findings demonstrate that biochar's effect on nitrogen retention is strongly pH-dependent, with optimal performance in the pH 4.5–6.4 range where it enhances ammonium immobilisation and suppresses nitrate formation. The results suggest biochar could improve nitrogen use efficiency and reduce NO₃⁻-N loss in subtropical citrus production systems when soil pH is managed appropriately.
UK applicability
The findings may have limited direct applicability to UK farming, as the study focuses on acidic red soils typical of subtropical pomelo orchards rather than temperate soils. However, the mechanistic insights into how biochar modulates nitrogen cycling across pH gradients could inform biochar application strategies in acidic UK upland soils or poorly drained clay soils where nitrogen retention is challenging.
Key measures
Gross mineralisation rate (TM); gross NH₄⁺ immobilisation rate (TI); heterotrophic nitrification (ONrec); autotrophic nitrification (ONH₄); soil pH (5 levels: 4.0, 5.1, 5.8, 6.6, 7.2); biochar dose (0% and 1%); ¹⁵N-tracer analysis
Outcomes reported
The study measured gross nitrogen mineralisation rates, ammonium immobilisation rates, heterotrophic and autotrophic nitrification rates, and nitrate-nitrogen loss across five soil pH levels (4.0–7.2) with and without 1% biochar amendment. Biochar improved nitrogen retention in the pH 4.5–6.4 range by enhancing immobilisation whilst inhibiting autotrophic nitrification.
Topic tags
Dig deeper with Pulse AI.
Pulse AI has read the whole catalogue. Ask about this record, its theme, or how the findings apply to UK farming and policy — every answer cites the underlying studies.