Shrub-Willow Living Snow Fences Impact on Soil Carbon and Nitrogen Pools and their Lability

Shrub-willow ( Salix spp.) living snow fences are an effective agroforestry practice for reducing blowing snow on roadways while providing ecosystem services such as soil carbon (SOC) sequestration and bioenergy feedstock production. Despite these benefits, research on SOC accumulation in willow systems is limited. This study aimed to evaluate the impact of different willow varieties on SOC and total nitrogen concentrations, stratification, and lability in marginal soil. A randomized complete block design with three willow varieties ( Salix purpurea ‘Fish Creek,’ S. purpurea × S. miyabeana ‘Oneonta,’ and S. caprea × S. cinerea ‘S365’) and control plots was used. Post-planting weed management included herbicide and manual control. Two years post-planting, composite soils were collected from geo-referenced sites within each plot at 0- to 90-cm depths and analyzed for SOC, total N, microbial biomass carbon (SMBC), metabolic quotient (qR), active C, cold and hot-water carbon (CWC & HWC), particulate organic carbon and nitrogen (POC & PON). All willow varieties, especially Fish Creek and Oneonta, significantly increased SOC and total N contents. Willow treatments positively influenced labile SOC and total N pools, with notable increments in SMBC, POC, and PON. Stratification of SOC and total N decreased with depth, particularly up to 0–45 cm. Carbon and nitrogen management indices (CMI & NMI) varied significantly among willow treatments, highlighting their potential to enhance SOC sequestration and total N dynamics. This study provides insights into the positive impact of specific willow varieties on soil properties, emphasizing the importance of SOC sequestration in managing marginal soils.