Utilizing woody residues for fungal-based management of soil nitrogen pools. Long_term_experiment

This study shows that addition of woody materials can lead to the capture excess soil nitrogen, diriven by the stimulation of saprotorphic fungi. The extent of nitrogen immobilization depends on the type and dose of a woody material. Based on this study, 3.5—5.3 t ha-1 deciduous wood sawdust potentially capture, for a period of 4—6 months, at least 21 and 30 kg N ha-1 with a background of mineral and organic fertilizer, respectively. Furthermore, 7—10.6 t ha-1 of beech wood sawdsut, or its combination with conifert wood or wood chips, immobilize up to 59 kg N ha-1 for more than 6 months. The slow remobilization of nitrogen into the soil pool is, possibly, influenced of multiple factors, such as fungal turnover, microbial recycling and chemical binding to residual lignocellulose. This strategy is therefore suitable managing soil nitgogen use efficiency over a medium/long period of time. For instance, it could be used for capturing nitrogen after crop harvest, until planting of subsequent cash/cover crops. Woody amendments could also be added in arable soils temporarily taken out of plant production for regenerating soil fertility and soil organic matter (e.g. in crop-fallow or crop-pasture rotations). Positive effects such as reduced nitrogen leaching, long-term promotoion of plant yield and soil quality are expected, yet these need to be throughly adressed in future reserch, in the field and/or greenhouse. Besides increasing nitrogen use efficiency, the woody amendments and stimulated fungi can provide other services to degraded soils. This study highlights that the use of woody amendments of larger particle size or of mixture of particle sizes could lead to a more complex stimulated fungal community, that includes combative wood-decay fungi.

本研究证实，添加木质材料可通过刺激腐生真菌（saprotrophic fungi）实现过量土壤氮素的固持。氮固持的程度取决于木质材料的类型与施用量。基于本研究结果，在矿质肥料与有机肥背景施肥条件下，3.5—5.3 t·ha⁻¹的落叶木锯屑可在4—6个月内分别固持至少21 kg N·ha⁻¹与30 kg N·ha⁻¹的氮素。此外，7—10.6 t·ha⁻¹的山毛榉木锯屑，或其与针叶木、木片的复配体系，可在6个月以上固持高达59 kg N·ha⁻¹的氮素。氮素向土壤库的缓慢再释放，可能受真菌周转、微生物循环以及与残留木质纤维素（lignocellulose）的化学结合等多种因素影响。因此，该策略适用于中/长期提升土壤氮素利用效率。例如，可用于作物收获后固持氮素，直至后续经济作物/覆盖作物种植。木质改良剂还可施用于临时暂停植物生产的耕地，以修复土壤肥力与土壤有机质（例如在作物休耕或作物-牧场轮作系统中）。预期可带来减少氮淋失、长期促进作物产量与改善土壤质量等积极效果，但这些仍需在田间与/或温室环境中开展深入研究加以验证。除提升氮素利用效率外，木质改良剂与被激活的真菌还可为退化土壤提供其他生态服务。本研究强调，使用大粒径或多粒径混合的木质改良剂，可构建更为复杂的激活真菌群落，其中包括具有拮抗能力的木材腐朽真菌。