Translocation and Allocation of Smooth Vetch-Derived Nitrogen Along the Plant-Soil Continuum in Citrus Orchards.

Smooth vetch-derived nitrogen primarily supports soil N pools, with less than 5% directly transferred to citrus fruits and leaves, highlighting soil stabilization over direct uptake.

• Why it matters: Understanding nitrogen flow in legume-based agroforestry systems is crucial for optimizing nutrient use efficiency and sustainable crop management, yet remains poorly characterized.
• What they did: An in situ 15 N labeling approach was used to trace smooth vetch-derived N during citrus and vetch co-growth and decomposition stages, analyzing soil fractions, microbial pathways, and fertilization effects.
• The result: Findings show fertilization enhances smooth vetch N retention in soil organic matter and microbial biomass, with soil-mediated N transfer supporting citrus nutrition, informing integrated nutrient management strategies.