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

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.