{
  "abstract": "IntroductionBiological nitrogen fixation (BNF) introduces new nitrogen (N) into legume-based systems, whereas plant-residue mulching primarily recycles N already present within the production system. We investigated whether N returned as mulch supplements atmospheric N acquisition or substitutes for it during red-clover (Trifolium pratense L.) regrowth.MethodsFollowing the first cut, red clover received no N input (TP-0), mineral N as a readily available-N reference (TP-N), red-clover mulch (TP-T), or Italian ryegrass (Lolium multiflorum Lam.) mulch (TP-L), with three replicate pots per treatment. After 55 d of regrowth, the proportion of aboveground N derived from the atmosphere (pNdfa) was estimated using the ¹⁵N natural-abundance method with treatment-specific non-legume references.ResultsAboveground dry matter and total N showed no detectable treatment differences (p = 0.835 and p = 0.840, respectively). In contrast, pNdfa declined from 63.0% in TP-0 to 41.5% in TP-N, 18.7% in TP-T, and 14.8% in TP-L (p < 0.001). Fixed-N accumulation was 0.771, 0.529, 0.223, and 0.190 g N pot⁻¹, respectively, whereas non-fixed N increased from 0.459 to 0.745, 0.948, and 1.028 g N pot⁻¹. Thus, N addition altered the source composition of the aboveground N pool much more strongly than its total size.DiscussionUnder mulch, lower atmospheric-N contribution coincided with greater accumulation of non-fixed N without a detectable increase in total aboveground N. These findings provide quantitative evidence that residue return can shift short-term N-source partitioning in regrowing red clover, with greater reliance on non-fixed N coinciding with reduced reliance on newly fixed atmospheric N.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Original Research",
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "name": "Abu Zar Ghafoor"
    },
    {
      "name": "Hassan Karim"
    },
    {
      "name": "Christopher Brock"
    },
    {
      "name": "Yongcheng Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/1hnqc9gxwycrk.bib",
  "cited_by": 0,
  "doi": "10.3389/fpls.2026.1970507",
  "fulltext_url": null,
  "id": "1hnqc9gxwycrk",
  "issns": [
    "1664-462X"
  ],
  "landing_url": "https://www.frontiersin.org/articles/10.3389/fpls.2026.1970507",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "feed-journal",
      "biology/plant-biology"
    ]
  ],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-06",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/1hnqc9gxwycrk.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T12:20:46Z",
      "native_id": "10.3389/fpls.2026.1970507",
      "source": "feed-frontiers",
      "url": "https://www.frontiersin.org/articles/10.3389/fpls.2026.1970507"
    },
    {
      "first_seen": "2026-11-06T12:21:14Z",
      "native_id": "10.3389/fpls.2026.1970507",
      "source": "crossref",
      "url": "https://www.frontiersin.org/articles/10.3389/fpls.2026.1970507/full"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "feed-journal:biology/plant-biology",
      "subfield": "plant-biology"
    }
  ],
  "title": "Residue mulching shifts nitrogen-source partitioning from atmospheric to non-fixed N during red clover regrowth",
  "title_text": "Residue mulching shifts nitrogen-source partitioning from atmospheric to non-fixed N during red clover regrowth",
  "type": "peer-reviewed",
  "updated_at": "2026-11-08T00:22:47Z",
  "url": "https://research.draconitic.com/paper/1hnqc9gxwycrk",
  "venue": "Frontiers in Plant Science",
  "versions": []
}